1. The size of a molecule is on the order of __________, and the size of an average cell is on the order of ____________.A. nanometer (nm), micrometer (μm)B. nanometer (nm), millimeter (mm)C. micrometer (μm), millimeter (mm)D. picometer (pm), millimeter (mm)E.
micrometer (μm), nanometer (nm)
A. nanometer (nm), micrometer (μm)
2. Which of these statements is incorrect?A. 1 meter = 10-3 mmB. 1 meter = 10-6 μmC. 1 meter = 10-9 nmD.
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All of the above are correctE. None of the above are correct
E. None of the above are correct
Which is the correct flow of genetic information in the cell?A. RNA translation DNA transcription ProteinB. RNA transcription DNA translation Protein C. DNA transcription RNA translation ProteinD. DNA translation RNA transcription ProteinE. RNA transcription Protein translation DNA
C. DNA transcription RNA translation Protein
Cells in a multicellular organism contain (nearly) identical copies of DNA, but turn on different sets of genes according to their developmental history and signals from outside the cell.
A. TrueB. False
The light microscope allows us to resolve details as small as ____, and this level of detail is limited by ______________________.A. 200 μm; the quality of the lensesB. 200 μm; the wavelike nature of lightC. 200 nm; the quality of the lensesD.
200 nm; the wavelike nature of light
D. 200 nm; the wavelike nature of light
Flourescent dyes absord light at one wavelength and emit at another, longer wavelengthA. TrueB. False
A confocal microscope differs from a typical fluorescence microscope in that: A. Confocal microscopy scatters light off the surface of the specimen giving striking 3-dimensional images of the object surface B. Confocal microscopy requires the samples be stained with fluorescent dyes. C.
Confocal microscopy is used to focus at different depths within the specimen allows a 3 dimensional fluorescent image to be constructed D. B & C E. All of the above
C. Confocal microscopy is used to focus at different depths within the specimen allows a 3 dimensional fluorescent image to be constructed
Which of the following is true regarding transmission electron microscopy (TEM)?A. TEM is in principle similar to a light microscope, but uses a beam of electrons rather than a beam of lightB. TEM samples must be very thinC.
Contrast is usually introduced by staining with electron-dense heavy metalsD. TEM can resolve details as small as about 2mmE. All of the above are true
D. TEM can resolve details as small as about 2mm
Which of the following is NOT true regarding scanning electron microscopy (SEM)?A.
SEM scatters electrons on the surface of the samplesB. Electrons are focused on the sample surface using electromagnetic coils that act as lensesC. SEM samples are coated with a very thin film of a heavy metalD. SEM is used to look at surface details with a resolution of ~3nm to 20nmE. All of the above are true
All os the above are true
Tissues are often chemically fixed and and cut into thin slices, or sections, for certain types of microscopy. This is done because:A.
Most tissues are not small enough or transparent enoughB. Most tissues require fixing for removalC. Fluorescent dyes require fixation for microscopyD. A and CE. All of the above
Most tissues are not small enough or transparent enough
What statement is NOT true about procaryotes?A.
Procaryotes use DNA to store their genetic informationB. Procaryotes store their genetic information in a nucleus.C. Procaryotes vary widely in shape and size.
D. Procaryotes are mostly single-celled organisms, but some are multicellular.E. All of the above are true about procaryotes
Procaryotes store their genetic information in a nucleus.
Bacteria can duplicate approximately every τ minutes. Assuming unabated growth with a doubling time of exactly τ minutes and 50 bacteria at time t=0, which equation correctly models the number of bacteria as a function of time (t) in minutes?A. τ * 50 ^ (t / τ)B. τ * 50 ^ (t)C.
Plants and animalsB. Animals and archaeaC. Archaea and bacteriaD. Bacteria and fungiE. None of the above
Archaea and bacteria
The DNA of a bacterial cell is found in the cytosol A. TrueB.
All of the DNA of a eukaryotic cell is contained within the nucleus.(T/F)
What role is NOT performed by the cytoskeleton?A. Pulling duplicated chromosomes to opposite poles in dividing cellsB. Transporting organelles and molecules from one place to another in the cytoplasmC.
Generating chemical energyD. Controlling cell shape and cell movementE. All of the above are performed by the cytoskeleton
Generating chemical energy
Which of the following is NOT a model organism?A. Escherichia coliB. Arabidopsis thalianaC. Drosophilia melanogasterD. Schizosaccharomyces cerevisaeE.
Caenorhabditis elegansF. All of the above are model organisms
All of the above are model of organisms
T/FMammals possess the largest genome of any known species
The human body consists of greater than 60% hydrogen atoms both as a total percentage of all atoms and also by mass.a. Trueb. False – hydrogen does NOT make up greater than 60% of all atomsc. False – hydrogen does NOT make up greater than 60% by massd. False – hydrogen does NOT make up greater than 60% either by mass or by count
False — hydrogen does NOT make up greater than 60% by mass
T/FBond length is directly proportional to bond length (i.
e. a longer bond has a higher energy).
Put the following bond types in order of increasing strength (i.e. starting with the weakest bond and ending with the strongest bond).(Weakest) (Strongest)a. Covalent < Ionic < Hydrogen < van der Waalsb. Hydrogen < van der Waals < Ionic < Covalentc.
Ionic <Hydrogen < van der Waals <Covalent d. van der Waals < Hydrogen <Ionic <Covalente. None of the above
van der Waals –> Hydrogen –> Ionic –> Covalent
At room temperature, corn oils are fluid while butter and lard are solid.
This is primarily due to:a. Corn oils are derived from plants while butter and lard are derived from animalsb. Fatty acids in butter/lard form bilayers while fatty acids in corn oil form micellesc. Corn oils contain a larger number of saturated fatty acidsd. Butter/lard contain a larger number of saturated fatty acidse. None of the above
Butter/lard contain a larger number of saturated fatty acids
Which of the following is NOT true regarding disaccharides:a. Are the simplest polysaccharidesb. Include maltose, lactose, and sucrosec.
Have the general chemical formula (CH2O)nd. Are formed via a condensation reaction of two monosaccharidese. All of the above are true
Have the general chemical formula (CH2O)n
The difference between a DNA nucleotide and a RNA nucleotide:a. Is in the sugar ringb.
Is in the pyrimidine compoundsc. Is in the purine compoundsd. Is in the phosphate groupe. A and Bf.
A and C
a and b
On which end of a DNA molecule, a chain of average length, is the phosphate group located? a. On the 5’ endb. On the 3’ endc. On both the 5’ and 3’ endsd. On neither the 5’ nor 3’ ende.
None of the above, DNA ends are labeled as N and C.
On the 5′ end
In an amino acid, which of the following is covalently linked to the ;-carbon?a. The amino group (-NH2)b. The carboxyl group (-COOH)c. The side chain group (-R)d. All of the above are covalently linked to the ;-carbone. None of the above
All of the above are covalently linked to the ;-carbon
Disulfide bonds can form between two _________ side chains.a.
How do protein, nucleic acid, and polysaccharide molecules polymerize (grow)?a. By condensation reactionsb. By hydrolysis reactionsc.
By oxidation reactionsd. All of the abovee. None of the above
By condensation reactions
Which type of bond makes it possible for a macromolecule to interact with great specificity with just one out of the many thousands of different molecules present inside a cell?a. Covalent bondsb. Noncovalent bondsc. Hydrogen bondsd.
The measure of disorder in a system is called ____________________.a. Free energyb. Oxidationc. Entropyd. Enthalpye. None of the above
Which of the following is NOT true regarding oxidation?a.
Oxidation refers to the addition of electronsb. Oxidation and reduction, the converse reaction, always occur simultaneouslyc. Cellular respiration involves the oxidation of carbon and hydrogen atoms to produce CO2 and H2O, respectivelyd. As an organic molecule, such as methane, is being oxidized, the number of C-H bonds decreasese.
Oxidation of NADPH, and important carrier of electrons, results in NADP+f. All of the above are true
Oxidation refers to the addition of electrons
Proteins called ___________ lower the activation energy of a biological reaction, the result is that ______________________________.a.
Substrates; the reaction proceeds with a lower overall free energy (DG)b. Enzymes; the reaction proceeds with a lower overall free energy (DG)c. Substrates; the reaction is more likely to proceed, but the overall free energy (DG) does NOT changed.
Enzymes; the reaction is more likely to proceed, but the overall free energy (DG) does NOT changee. None of the above
Enzymes; the reaction is more likely to procedd, but overall free energy (DG) does NOT change
Suppose for a simple reaction Y X that ;G = 5 kcal/mol and [Y] = 1 mol and [X] = e10 mol. What is the approximate free-energy change, ;G, for the reaction?a. ;G = 5e10 kcal/molb. ;G = -5.6 kcal/molc. ;G = 5.
6 kcal/mold. ;G = 11 kcal/mole. None of the abovef.
Not enough information to calculate ;G
;G = 11 kcal/mol
The ; G; of the hydrolysis reaction of ATP is -7.3 kcal/mole, but in a cell the actual ; G is much more __________ , this is because _______________________________.a. Positive, ATP is much higher in concentration than the products ADP and Pi.
b. Positive, ATP is much lower in concentration than the products ADP and Pi.c. Negative, ATP is much higher in concentration than the products ADP and Pi.
d. Negative, ATP is much lower in concentration than the products ADP and Pi.
Negative, ATP is much higher in concentration than the products ADP and Pi
Which of the following statements is NOT true?a.
Vmax is the same for Reaction X and Reaction Yb. Km is greater for Reaction X than for Reaction Yc. The equation for the left plot is:d. Reaction 1 corresponds to Reaction Y while Reaction 2 corresponds to Reaction Xe. All of the above are true
Km is greater for Reaction X than for Reaction Y
If the two reactions, Reaction 1 and 2, represent the same reaction with and without a competitive inhibitor, and the same is true for Reactions X and Y, which of the two reactions on each plot would be the one that contains the inhibitor?a. Reaction 1 and Reaction Y contain the inhibitorb.
Reaction 1 and Reaction X contain the inhibitorc. Reaction 2 and Reaction Y contain the inhibitord. Reaction 2 and Reaction X contain the inhibitor
Reaction 1 and Reaction Y contain the inhibitor
Which of the following statements is NOT true?a. NADPH is an activated carrier molecule that is usually used in biosynthetic reactions to build energy-rich molecules.b. NADPH is an activated carrier molecule that is used primarily by plants.c.
NADH is an activated carrier molecule that is usually used in oxidation reactions to produce ATP.d. NADH carries an extra proton and two high-energy electrons.
e. All of the above statements are true.
NADPH is an activated carrier molecule that is used primarily by plants.
T/FSynthesis of macromolecules, including DNA, RNA, polysaccharides and proteins requires an input of energy, often driven by energy from nucleoside triphosphate hydrolysis.
The amino acid sequence of a protein is always presented and read in the:A.
N to C directionB. C to N directionC. 5; to 3; directionD. 3; to 5; direction
N to C direction
Which of the following does NOT stabilize the folded structure of a protein:A. Covalent bondsB. Backbone to backbone hydrogen bondsC.
Side chain to side chain hydrogen bondsD. Disulfide bondsE. Van der Waals attractionsF. All of the above contribute to protein structure
All of the above contribute to protein structure
When exposed to high concentrations of urea, proteins become denatured. Which of the following is NOT true regarding protein denaturation using urea?A. Urea is a small moleculeB. Urea acts as both a hydrogen bond acceptor (via ;NH2 groups) and a hydrogen-bond donor (via ;C=O group) to destabilize hydrogen bondsC.
Urea does NOT destabilize covalent bonds within a protein structureD. Urea, at high concentrations, destabilizes the hydrogen-bonded network of water molecules thus diminishing hydrophobic forces within a protein structureE. All of the above are true
Urea acts as both a hydrogen bond acceptor ( via -NH2 groups) and a hydrogen bond donor (via- C=O group) to destablize hydrogen bonds
T/FThe two regular folding patterns in proteins are the ;-helix and ;-sheet, both of which result from hydrogen bonds forming between backbone amine and carbonyl groups
In a ;-helix, a hydrogen bond is formed between every ________ amino acid, and the helix completes a turn approximately every ________ amino acids.A.
Third; 3.6B. Third; 4C. Fourth; 3.
6D. Fourth; 4E. None of the above
Some protein molecules contain an assembly of two different subunits. Hemoglobin contains two copies of ;-globin and two copies of ;-globin.
The complete structure is called the ______________________.A. Primary structureB. Secondary structureC. Tertiary structureD. Quaternary structureE. Quinary structure
In theory, a polypeptide chain with n residues has _____ different possible sequences and _______________ of these sequences adopt a single, stable conformation.
A. 20^n; nearly allB. 20^n; very fewC. n^20; nearly allD. n^20; very fewE. 20*n; nearly allF.
20*n; very few
20^n; very few
What is the name of the enzyme class responsible for catalyzing the rearrangement of bonds within a single molecule?A. NucleaseB. ProteaseC. IsomeraseD. SynthaseE.
Which of the following statements regarding antibodies is NOT true?A. An antibody is a protein ligand that binds a target protein with high affinityB. Antibodies contain two identical binding sites, a result of two identical light chains and two identical heavy chainsC. Antibodies are produced by T cellsD. Antibodies can be coupled to fluorescent dyes for fluorescence microscopy or to gold particles for electron microscopyE. Some assays require antibodies that bind to other antibodiesF.
All of the above are true
Antibodies are produced by T cells
T/FMost drugs work by inhibiting enzymes
Hemoglobin binds four oxygen molecules. Suppose oxygen binding to the heme group (the subunit within hemoglobin) facilitates further oxygen binding. This is an example of:A. Ligand bindingB. Allosteric regulationC.
Feedback inhibitionD. A and BE. A, B and C
A and B
Proteins are phosphorylated via the enzyme ___________________, and the addition of a phosphate group results in the addition of ______________________ to the target protein. A. Protein kinase; two negative chargesB. Protein phosphatase; two negative chargesC. Protein kinase; two positive chargesD. Protein phosphatase; two positive chargesE. None of the above
A. Protein kinase; two negative charges
The attachment or removal of modifying groups to a protein can control what aspects of the protein?A.
Its behavior or activityB. Its stability or its binding partnersC. Its location inside the cellD. A and BE. A and CF.
A, B and C
F. A, B and C
How do most motor proteins make their movements unidirectional (i.e., irreversible)?A.
They couple a conformational change to a thermodynamically unfavorable reaction.B. They couple a conformational change to the hydrolysis of an ATP molecule.C.
They couple a conformational change to the formation of an ATP molecule from ADP and Pi.D. They couple a conformational change to the formation of a GTP molecule from GDP and Pi.
B. They couple a conformational change to the hydrolysis of an ATP molecule.
The attachment or removal of modifying groups to a protein can control what aspects of the protein?A. Its behavior or activityB.
Its stability or its binding partnersC. Its location inside the cellD. A and BE. A, B and C
E. A, B and C
Using mass spectrometry, proteins are selectively digested (using trypsin digestion, for example) and then separated based on their:A. Mass to length ratioB.
Mass to charge ratioC. Mass to hydrophobicity ratioD. Mass to structure ratioE. Radial distribution function
Mass to charge ratio
The large scale study of cellular proteins (studying the activities or structures of many proteins) is called what?A. ProteomicsB. GenomicsC.
MetabolomicsD. BioinformaticsE. Electrophoresis
A cell homogenate (or cell extract) contains large and small molecules as well as membrane enclose organelles.
Which of the following is NOT used for homogenization of cells or tissues?A. High frequency soundB. Mild detergentsC. High pressureD. Shearing cellsE.
Density gradient centrifugation is used to separate cell components on the basis of their __________________.A. Primary amino acid sequenceB. Mass and chargeC. Buoyant densityD. Sucrose contentE. Radial distribution function
In gel electrophoresis, what is the purpose of adding SDS to samples?A. Solubilization of proteinsB.
Breaking disulfide bondsC. Covering proteins with the negatively charged detergentD. A and CE. B and CF. A, B and C
A and C
The nucleotide sequence of one DNA strand of a DNA double helix is:5;;GGATTTTTGTCCACAATCA;3;. What is the sequence of the complementary strand?a. 3; ; TGATTGTGGACAAAAATCC – 5;b.
5; – TGATTGTGGACAAAAATCC – 3;c. 5; – CCTAAAAACAGGTGTTAGT – 3;d. 3; – GGATTTTTGTCCACAATCA – 5;e. None of the above
5; – TGATTGTGGACAAAAATCC – 3;
Assume the following DNA sequences are bound to their complementary strands, which of the following DNA sequences would you expect to require the lowest temperature to break the two strands apart?a. 5;- GATCCAGA -3;b. 5;- GATCCAAA -3;c. 5;- GATAAAGA -3;d. 5;- GATCCAGG -3;e.
The strands are the same
5;- GATAAAGA -3;
The polarity in a DNA strand is indicated by referring to one end as the 5; end and the other as the 3; end. Which chemical moiety is located on the 3; end?a. Amine groupb. Carboxyl groupc. Phosphate groupd.
Hydroxyl groupe. The moiety depends on the direction the DNA strand is being read
A gene is a segment of DNA that ultimately codes for a protein or a set of related proteins. Alternatively, some genes code for RNA molecules as their final product.a. Trueb. False
What does the term genome refer to?a. All of the proteins expressed in an organismb.
The complete set of information in the DNA of an organismc. The set of genes turned on in an organism, tissue, or celld. The observable character of a cell or organisme. None of the above
The complete set of information in the DNA of an organism
Which of the following statements is NOT true regarding chromosomes?a. Eukaryotic DNA is made up of linear, double-stranded DNAb. Bacteria typically carry their genes on a single, circular DNA moleculec. Sex chromosomes are non-homologous chromosomes with the Y chromosome maternally inherited and the X chromosome paternally inherited.
d. Abnormal chromosomes are associated with some genetic defectse. All of the above are true
Sex chromosomes are non-homologous chromosomes with the Y chromosome maternally inherited and the X chromosome paternally inherited.
The structures that cap the ends of eucaryotic chromosomes are called ______________, and the structure that allows each duplicated eucaryotic chromosome to be pulled into a daughter cell is called a _______________.a. Centromeres; telomereb. Telomeres; centromerec. Mitotic spindles; telomered.
Centromeres; mitotic spindle
A cell can change its pattern of gene expression by:a. Histone tail modificationb. Remodeling the chromatinc. Condensing the chromatin into heterochromatind. Replicating the DNA yielding two identical copiese. A, B, and Cf.
All of the above
A, B, and C
In a cell with decreased levels of histone deacetylases (the enzyme responsible for removing acetyl groups from histones), we would expect, compared to cells having normal levels of histone deacetylases:a. Increased histone acetylationb. Altered gene expressionc. Altered chromatin structured. A and Be. A, B and C
Consider the process that a cell uses to replicate its double-stranded DNA to make copies for daughter cells. Which statement describes the DNA in daughter cells?a. The double helix in one daughter cell consists of two strands that were originally in the parent cell, while the double helix in the other daughter cell consists of two newly made strands.
b. The two strands of the double helices in both daughter cells consist of segments of new and parental DNAc. The double helices in each daughter cell consist of one parental strand and one newly made strand.d. The two strands of the double helices in both daughter cells consist of segments that were originally in the parental cell.
The double helices in each daughter cell consist of one parental strand and one newly made strand.
DNA synthesis begins at:a. The telomeresb. The centromerec. The replication originsd. The CpG islands
The replication origins
At the leading strand the DNA is synthesized ______________, and at the lagging strand the DNA is synthesized ________________.a. Continuously; continuouslyb.
Continuously; discontinuouslyc. Discontinuously; discontinuouslyd. Discontinuously; continuouslye. None of the above
Replication origins typically consist of a small stretch of DNA that is relatively easy to open. Which statement is true?a. Replication origins are rich in A and T nucleotides.b. Replication origins are rich in G and C nucleotides.
c. Replication origins have equal numbers of A, C, G, and T nucleotides.
Replication origins are rich in A and T nucleotides.
DNA is synthesized in the _________, and DNA is proofread in the _________.a. 5; to 3; direction; 3; to 5; directionb. 5; to 3; direction; 5; to 3; directionc.
3; to 5; direction; 3; to 5; directiond. 3; to 5; direction; 5; to 3; direction
5; to 3; direction; 3; to 5; direction
Most cancers arise from cells that have accumulated only a single mutation.a.
How does ultraviolet radiation in sunlight typically damage DNA?a. It breaks hydrogen bonds between the two strands of DNA.b. It removes bases from nucleotides in DNA. c.
It promotes covalent linkage between two adjacent pyrimidine bases.d. It promotes covalent linkage between two adjacent purine bases
It promotes covalent linkage between two adjacent pyrimidine bases.
Nearly half of the human genome is made up of copies of various mobile genetic elements.a. Trueb.
Homologous recombination takes place only between two DNA molecules with an identical sequence.a. Trueb. False
Retroviruses like HIV:a. Must copy their RNA genomes into DNA to replicate.b.
Must copy their DNA genomes into RNA to replicate.c. Must copy the host;s genome to replicate.d. Contain no genes of their own.
Must copy their RNA genomes into DNA to replicate.
RNA and DNA differ in their chemical structure. Which of the following is true?a.
RNA and DNA differ in their sugar groupb. RNA and DNA differ in their phosphate groupc. RNA and DNA differ in their basesd. RNA and DNA differ in their phosphodiester bonde. A and C are truef. B and D are true
A and C are true
Pictured to the right is a nucleic acid, which nucleic acid is this?a. 5;, 2; RNAb. 5;, 2; DNAc.
5;, 3; RNAd. 5;, 3; DNAe. The DNA/RNA designation depends only on the ;BASE; groups
5;, 3; RNA
RNA, as opposed to DNA, can fold into complex three-dimensional structures because it is single-stranded.
a. Trueb. False
Which of the following statements is NOT true?a. pRNAs code for proteinsb. rRNAs form the core of the ribosome and catalyze protein synthesisc. tRNAs serve as adaptors between mRNA and amino acids during protein synthesisd. miRNAs (or microRNAs) regulate gene expressione. All of the above are true
pRNAs code for proteins
In eucaryotes, what must assemble at a promoter before RNA polymerase can transcribe a gene?a.
Nucleotides required in transcriptionb. General transcription factorsc. Sigma factord. An RNA primere. A and D
General transcription factors
The assembly of general transcription factors to a eucaryotic promoter begins at what site in a promoter?a.
The assembly boxb. The TATA boxc. The GAGA boxd. The TFIID boxe.
None of the above
The TATA box
In a eukaryotic gene, coding regions are known as _______ and non-coding regions are known as ________.a. Exons; introns; prokaryotic genes have similar organization of coding regionsb. Introns; exons; prokaryotic genes have similar organization of coding regionsc.
Exons; introns; prokaryotic genes do not contain intronsd. Introns; exons; prokaryotic genes do not contain introns
Exons; introns; prokaryotic genes do not contain introns
The three nucleotide codon can be arranged into ______ combinations, and ___________________________.a. 43 = 64; each combination codes for a unique amino acidb. 4^3 = 64; due to redundancy in the code, there are only 20 amino acidsc. 3^4 = 81; each combination codes for a unique amino acidd. 3^4 = 81; due to redundancy in the code, there are only 20 amino acidse. None of the above are true
4^3 = 64; due to redundancy in the code, there are only 20 amino acids
Of the total mRNA that is synthesized, only a small fraction;the mature mRNA;is useful to the cell.
The cell distinguishes between mature mRNA molecules and debris RNA molecules generated by RNA processing using RNA binding proteins (such as poly-A-binding brotein and cap-binding protein) that allow the mRNA to be transported out of the nucleus and into the cytosol.a. Trueb. False
The structure of the ribosome, which is made up of greater than 50% RNA by mass, confirms that the RNAs (not the proteins) are responsible for the structure and catalytic activity. Therefore the ribosome is actually a __________________.a. RNAzymeb. Protozymec.
Ribozymed. Enzonucleic acide. None of the above
Within the ribosome, the formation of peptide bonds is catalyzed by:a. Aminoacyl-tRNA synthetase.b. The tRNA itself.
c. An RNA molecule in the large ribosomal subunit.d. A peptidase in the small ribosomal subunit.
An RNA molecule in the large ribosomal
During translation at the ribosome, peptide bond formation forms when the N-terminal (upstream) tRNA is in the __________ and the C-terminal (downstream) tRNA is in the __________.
Discovered in the polio virus in 1988, the internal ribosomal entry site (IRES) is described as ;distinct regions of RNA molecules that are able to attract the eukaryotic ribosome therefore allowing translation,; similar to those found in prokaryotic RNAs.
In an experiment within eukaryotic cells, what advantage does the IRES yield?a. Translation of a single mRNA molecule yielding many copies of the same proteinb. Translation of a single mRNA molecule yielding copies of several different proteinsc. Translation of multiple different RNA molecules yielding many copies of the same proteind. Translation of multiple different RNA molecules yielding copies of several different proteins
Translation of a single mRNA molecule yielding copies of several different proteins
Which of the following mutational changes would be most harmful to an organism?a. Removal of a single nucleotide near the end of the coding sequenceb. Removal of a single nucleotide within an intron at the beginning of the sequencec. Deletion of three consecutive nucleotides in the middle of the coding sequenced.
Removal of a single nucleotide near the beginning of the coding sequencee. Substitution of one nucleotide for another in the middle of the coding sequence
Removal of a single nucleotide near the beginning of the coding sequence
Which of the following statements is NOT true about the differences between liver cells and kidney cells in the same organism?a. They contain the same genes, but express them differently.b. They contain different genes.c. They contain different sets of proteins.d.
They contain different sets of RNAse. B and D
They contain different genes.
Although all of the steps involved in expressing a gene can in principle be regulated, for most genes the most important point of control is:a. Transcription initiationb. RNA processingc. RNA transport and localizationd.
mRNA degradatione. mRNA translation
Which of the following is false?a. Eucaryotic gene activator proteins stimulate transcription initiation by recruiting proteins that modify chromatin structure.b. A: Eucaryotic gene activator proteins stimulate transcription initiation by aiding in the assembly of general transcription factors and RNA polymerase at the promoter.
c. Eucaryotic gene activator proteins stimulate transcription initiation by recruiting a DNA polymerase to the promoter.d. Eukaryotic gene activator proteins, such as transcription regulators, bind either upstream or downstream of the gene itselfe. All of the above are true
Eucaryotic gene activator proteins stimulate transcription initiation by recruiting a DNA polymerase to the promoter.
DNA methylation is a ____________________, and the transmission from parent to daughter cell of the methylated pattern of DNA that effect protein expression without altering the DNA base pair sequence is known as ___________________________.a. Post-transcriptional control mechanism; single nucleotide polymorphismb.
Post-transcriptional control mechanism; epigenetic inheritancec. Post-translational control mechanism; single nucleotide polymorphismd. Post-translational control mechanism; epigenetic polymorphisme. Transcriptional control mechanism; single nucleotide polymorphismf. Transcriptional control mechanism; epigenetic inheritance
Transcriptional control mechanism; epigenetic inheritance
What type of molecule triggers RNA interference (RNAi)?a. Foreign, single-stranded DNAb. Foreign, double-stranded RNAc. Foreign DNA-RNA hybridsd.
All of the above
Foreign, double-stranded RNA
What is a riboswitch?a. A small molecule that regulates the translation of specific mRNAs.b. A gene regulatory protein that turns on the expression of ribosomal proteins.c. An mRNA that can regulate its own transcription and translation.d. RNAi that targets the ribosomee.
None of the above
An mRNA that can regulate its own transcription and translation.
Which of the following is NOT a source of genetic variation crucial in evolution?a. Mutation within a geneb. Mutation within the promoter of a genec.
Exon Shufflingd. Horizontal gene transfere. All of the above are sources of genetic variation
All of the above are sources of genetic variation
Many mutations are accumulated in an organisim over time. Of those mutations, the only mutations that are passed on to the next generation are those that occur in a ____________.a. Somatic cellb. Germ cellc.
Embryonic stem celld. Tumor celle. All of the above
Nucleotide point mutations that lead to no change in the amino acid sequence of any protein are known as silent, selectively neutral mutations and accumulate in the genome of a species over evolutionary time.a. Trueb.
The two globin genes, ;- and ;- globin, that make up the hemoglobin molecule are a result of:a. Gene duplicationb. Horizontal transferc. Gene mutationd. A and Be. A and C
A and C
Given the following phylogenetic tree, the arrow points in the direction of:a. Increasing time before presentb. Decreasing time before presentc. Percentage nucleotide substitutiond. A and Ce. B and C
A and C
In our human ancestors, the enzyme lactase, which allows us to digest the milk sugar lactose, was produced only during infancy. Today, a portion of the adult population can digest lactose while other adults remain lactose intolerant. Which adults have point mutations in the regulatory DNA of their lactase genes?a. Those who are lactose intolerantb. Those who can digest lactose
Those who can digest lactose
Most of the genetic variation in human genome takes what form?a. Single nucleotide polymorphismb. DNA duplications or deletionsc. Chromosomal rearrangementsd. Exon shufflinge. Intron shuffling
Single nucleotide polymorphisms
The human genome consists of approximately 3.2×10^9 nucleotide pairs, and only a few percent of that DNA codes for protein and for structural, regulatory, and catalytic RNAs.a. Trueb. False
An organism can produce far more proteins than it has genes. This is in; part due to the ability of cells to produce a range of related but distinct proteins from a single gene via unique RNA transcripts in a process called….a. Alternative transcriptionb. Alternative translationc. Exon shufflingd. Alternative splicinge. Single nucleotide polymorphism
Which of the following statements regarding restriction nucleases ( restriction enzymes) is NOT true?a. Restriction nucleases provide a bacterial defense mechanism against foreign DNAb. Restriction nucleases cleave specific protein sequences typically between 4-8 residuesc. Restriction nucleases typically recognize and cleave palindromic sequencesd. A longer restriction nuclease target sequence is less likely to occur by random changee. All of the above are true
Restriction nucleases cleave specific protein sequences typically between 4-8 residues
Gel electrophoresis separates DNA based on____________ whereby ____________.a. Fragment size; the smaller the molecule the faster the migrationb. Fragment size; the larger the molecule the faster the migrationc. Fragment sequence; the higher G/C content the faster the migrationd. Fragment sequence; the higher A/T content the faster teh migratione. None of the above is correct
Fragment size; the smaller the molecule the faster the migration
Because DNA is negatively charged, DNA fragments migrate toward a positive electrode.a. Trueb. False – DNA is positively charged and migrates toward a negative electrodec. False – DNA is negatively charged and migrates toward a negative electroded. False – DNA migration requires the addition of SDS, an anionic surfactant, allowing DNA; to migrate toward a positive chargee. False – DNA migration requires the addition of SDS, a cationic surfactant, allowing DNA to migrate toward negative charge
Which of the following enzymes allows scientists to join together DNA fragments?a. DNA polymeraseb. DNA ligasec. Restriction nucleased. DNA helicase
A DNA fragment, such as a vector, can be replicated inside ____________, and the process of introducing the fragment into the cell is a process called ____________.a. Mammalian cells; Transformationb. Mammalian cells; Recombinationc. Bacterial cells; Transformationd. Bacterial cells; Recombinatione. None of the above
A bacterial plasmid that contains a viral promoter and a mammalian gene is an example of recombinant DNA.a. Trueb. False
Suppose two DNA fragments were cute by different restriction nucleases that recognize different target sequences but generate the same single-stranded overhang (“sticky-ends”) — an example, BamHI and BglII is shown. Which is true of the resulting DNA fragments?a. The two fragment can NOT be ligated togetherb. The two fragments can be ligated together, and the resulting, ligated DNA can be cut by either restriction nucleasec. The two fragments can be ligated, and the resulting ligated DNA can be cut by only one of the original restriction nucleasesd. The two fragments can be ligated, and the resulting, ligated DNA is not recognized by either restriction nuclease
The two fragments can be ligated, and the resulting, ligated DNA is not recognized by either restriction nuclease
The process of making DNA from messenger RNA is known as______________ and the result is a ______________.a. Reverse transcription; messenger DNA libraryb. Reverse transcription; complementary DNA libraryc. Reverse translation; messenger DNA libraryd. Reverse translation; complementary DNA librarye. None of the above
Reverse transcription; complementary DNA library
The difference between cDNA and genomic DNA is:a. cDNA lacks exonsb. cDNA lacks intronsc. cDNA is tissue specific while genomic DNA is the same in every tissued. A and Ce. B and C
B and C
The correct sequence of steps in polymerase chain reaction (PCR) is __________________ , and, assuming you start with one double-stranded DNA molecule, after N cycles the number of double-stranded DNA molecules is __________________.a. Denaturation > Primer hybridization > DNA synthesis; N2b. Denaturation > DNA synthesis > Primer hybridization; N2c. Denaturation > DNA synthesis > Primer hybridization; 2N d. Denaturation > Primer hybridization > DNA synthesis; 2Ne. None of the above
Denaturation > Primer hybridization > DNA synthesis; 2^N
In the dideoxy method of sequencing DNA, if the ration of deoxyribonucleotide triphosphates (dATP, dTTP, dCTP, dGTP) to dideoxyribonucleotide triphosphates (ddATP, ddTTP, ddCTP, ddGTP) is increased:a. The strand polymerization terminates more frequentlyb. The strand polymerization terminates less frequentlyc. These conditions are favorable for determining short nucleotide sequencesd. A and Ce. B and C
The strand polymerization terminates less frequently
Lipid membranes are essentially two-dimensional fluids.a. Trueb. False
Which of the following molecules is NOT amphipathic?a. Phospholipidsb. Sterolsc. Glycolipidsd. Triacylglycerolse. Detergentsf. All of the above are amphipathic molecules
The fluidity of a membrane containing all unsaturated lipids is greater than the fluidity of a membrane thatcontains all saturated lipidsa. Trueb. False
A membrane that contains cholesterol is more fluid than the same membrane without cholesterol.a. Trueb. False
Which is the correct structural schematic for phosphatidylcholine?
Phospholipids can move within a membrane bilayer. Which of the following types of movement is least likely tooccur?a. Lipid lateral diffusion (diffusion within a monolayer)b. Lipid flip-flop (moving from one monolayer to the other)c. Lipid flexion (changing the lipid tilt angle)d. Lipid rotation (rotation about an axis normal to the bilayer)e. All of the above are equally likely to occur
Lipid flip-flop (moving from one monolayer to the other)
The α-helix is a stable membrane-spanning protein structure because:a. Hydrophobic amino acids are exposed on the outside of the helixb. Hydrogen bonds stabilize the hydrophilic peptide backbone, shielding it from the lipid tailsc. Hydrogen bonds stabilize the hydrophobic peptide backbone, shielding it from the lipid tailsd. A and Be. A and C
A and B
Vegetable shortening is made by hydrogenation of vegetable oils. In the process of hydrogenation, thehydrocarbon tails have had what treatment?a. The addition of double bonds (i.e. changing single bonds to double bonds)b. The removal of double bonds (i.e. changing double bonds to single bonds)c. The addition of carbon atomsd. The removal of carbon atomse. None of the above
The removal of double bonds (i.e. changing double bonds to single bonds)
Given the results for two plasma membranes (PM-I and PM-II) from fluorescence recovery after photobleaching (FRAP) shown to the right, which of the following statements is correct?a. PM-I is more fluid than PM-IIb. PM-I may contain a higher percentage of lipids with unsaturated hydrocarbon tailsc. PM-I may contain more cholesterol than PM-IId. A and Be. All of the above are correct
A and B
Which of the following is NOT an important function of cell surface carbohydrates?a. The carbohydrate layer protects the cell from mechanical damage.b. The carbohydrate layer protects the cell from chemical damage.c. Cell-surface carbohydrates play a role in cell adhesion.d. Cell-surface carbohydrates play a role in cell-cell recognition.e. All of the above are important functions of cell-surface carbohydrates.
All of the above are important functions of cell-surface carbohydrates.
Lipid bilayers are highly impermeable to:a. Waterb. Na+ and Cl-c. Oxygend. Ethanole. The bilayer is impermeable to all of the abovef. The bilayer is permeable to all of the above
Na+ and Cl-
Which of the following statements is true? a. Inside the cell the quantity of positively charged ions is almost exactly equal to the quantity of negatively charged ions.b. Inside the cell the quantity of positively charged ions is greater than the quantity of negatively charged ions.c. Inside the cell the quantity of positively charged ions is less than the quantity of negatively charged ions.
Inside the cell the quantity of positively charged ions is almost exactly equal to the quantity of negatively charged ions.
In a typical animal cell, which of the following types of transport occur through a channel protein?a. Movement of amino acids into a cellb. Movement of Na+ out of a cellc. Movement of Na+ into a celld. Movement of glucose into a starved celle. Movement of glucose out of a starved cell
Movement of Na+ into a cell
Why is Na+ commonly used to drive coupled inward transport of nutrients in animal cells?a. The chemical gradient drives Na+ into the cellb. The electrical gradient drives Na+ into the cellc. Both A and Bd. Neither A nor B
Both A and B
The high intracellular concentration of K+ in a resting animal cell is partly due to:a. The K+ leak channels in the plasma membraneb. The Na+-K+ pump in the plasma membranec. Voltage-gated K+ channels in the plasma membraned. Intracellular stores of K+ in the endoplasmic reticulume. The membrane potential
The Na+-K+ pump in the plasma membrane
Which of the following statements is NOT true regarding the Nernst equation:a. The Nernst equation can be used to calculate the resting potential of a membrane.b. The Nernst equation does not depend on the charge of the ion.c. The Nernst equation takes into account the electrical gradient.d. The Nernst equation takes into account the chemical gradient.e. All of the above are true.
The Nernst equation does not depend on the charge of the ion.
The patch-clamp technique can characterize the behavior of a single ion channel. The example shows a result for a particular cAMP-activated Cl- channel on the luminal membrane from frog skin. The units on the x-axis are ___________ and the units on the y-axis are ________________.a. time; voltageb. voltage; timec. current; voltaged. voltage; currente. time; currentf. current; timeg. time; arbitrary units of science
Ion channels of the auditory hair cells are opened by _______________ and thus transmit an electrical to the auditory nerve and to the brain.a. Ligand stimulusb. Mechanical stimulusc. Electrical stimulusd. All of the abovee. None of the above
The action potential travels in one direction because:a. The Na+-K+ pump restores the concentrations of Na+ and K+ to their original levels.b. The K+ leak channels allow K+ to flow out, restoring the membrane to the resting potential.c. Depolarization of the membrane causes voltage-gated K+ channels to open.d. Voltage-gated Na+ channels adopt a transitory inactive conformation after being opened.e. Voltage-gated Na+ channels spend less time in the open conformation when the membrane returns to the resting potential.
Voltage-gated Na+ channels adopt a transitory inactive conformation after being opened.
Which of the following is NOT a benefit of using a chain of neurons and chemical synapses rather than a direct connection between the site of stimulus and the site of response?a. Each chemical synapse represents an opportunity for the organism to modify the signal being sent.b. Diffusion of small molecules is more rapid than propagation of an electric signal, thus the signal is accelerated by having more synapsesc. Use of chemical synapses increases the variety of messages the presynaptic cell can sent to the post synaptic celld. Modification of different ion channels at synapses can be used to generate memory on the cellular level.e. Chemical synapses allow neurons to receive and integrate input from more than one source.
Diffusion of small molecules is more rapid than propagation of an electric signal, thus the signal is accelerated by having more synapses
The energy released by oxidizing glucose is saved in a high-energy bonds of:a. ATP and other activated carrier molecules.b. ADP and other activated carrier molecules.c. GDP and other activated carrier molecules.D. H2O and CO2E. none of the above
ATP and other activated carrier molecules.
Per molecule of glucose, the net production of glycolysis is:A. Two molecules of pyruvateB. Four molecules of ATPC. Two molecules of NADHD. A and B E. A and CF. A, B, and C
A and C
Fermentation is a useful method for generating energy, however the usefulness is limited because the end products are toxic to the producer.A. TrueB. False
Yeast : Ethanol :: Muscle cells : _______________A. PyruvateB. ATPC. NADHD. LactateE. None of the above
Fermentation results in the net production of:A. 2 ethanol moleculesB. 2 ATP moleculesC. 2 NADH moleculesD. A and BE. All of the above
A and B
Anaerobic respiration differs from fermentation in that it involves an electron-transport chain embedded within a membrane.A. TrueB. False
When fatty acids are oxidized to acetyl CoA, each cycle of the reaction removes how many carbon atoms from the fatty acid molecule?A. 1B. 2C. 3D. 4
The complete oxidation of glucose to H2O and CO2 produces how many ATP molecules per molecule of glucose?A. 2B. 4C. 12D. 20E. 30
Glucose subunits are stored as glycogen in animals and as starch in plants; both animals and plants store fatty acids as fats.A. TrueB. False
Cells obtain most of their energy by a membrane-based mechanism.A. TrueB. False
Which of the following statements regarding the electron-transport chain is NOT true?A. The transmembrane gradient of H+ serves as a source of energy to drive reactions such as ADP phosphorylation to generate ATP.B. The final product of the transport chain is waterC. High-energy electrons, as they fall to lower energy states, drive protons across the membrane, from the inner mitochondrial compartment to the cytosolD. The chain of electron carriers is embedded in the inner mitochondrial membrane in eukaryotic cellsE. The chain of electron carriers is embedded in the plasma membrane of bacteria.F. All of the above are true
High energy electrons, as they fall to lower energy states, drive protons across the membrane, from the inner mitochondrial compartment to the cytosol.
12. NADH donates its electrons to the electron transport chain and becomes NAD+. Which of the following statements regarding the conversion of NADH to NAD+ is NOT true?A. Electrons are donated from NADH via oxidationB. A hydride ion, having a negative charge, is donated from a methylene group within NADHC. Upon donating the hydride ion, NADH forms a temporary, unstable isomer before rearranging its bonds such that the positive charge is transferred from a carbon (unstable) to a nitrogen (stable) forming NAD+D. The hydride ion is made up of a hydrogen atom and two extra electrons, with the two electrons being donated to the electron transport chainE. FADH2 carries its electrons in a similar wayF. All of the above are true
The hydride ion is made up of a hydrogen atom and two extra electrons, witht the two electrons being donated to the electron transport chain
The total electrochemical potential of H+ across the inner mitochondrial membrane consists of a large force due to the membrane potential (DV) and a smaller force due to the H+ concentration gradient (DpH), with the electrochemical gradient driving H+ into the mitochondrial intermembrane space.A. TrueB. False
Identify the correct path for an electron through the electron transport chain:I. cytochrome b-c1 complexII. OxygenIII. NADHIV. cytochrome oxidase complexV. NADH dehydrogenase complexVI. UbiquinoneVII. Cytochrome C
III,V, VI, I, VII, IV, II
Which of the following statements regarding ATP synthase is NOT true?A. ATP synthase is a mitochondrial membrane proteinB. ATP synthase utilizes the electrochemical gradient of H+ in the mitochondria to synthesize ATPC. ATP synthase synthesizes ATP as H+ flows across the mitochondrial inner membrane into the mitochondrial matrix.D. ATP synthase is a reversible device that can hydrolyze ATP to drive H+ against the electrochemical gradient back into the intermitochondrial spaceE. All of the above are true
All of the above are true
The standard redox potential is for a 1:1 mixture of the redox pair. The standard redox potential for NADH and NAD+ is -320mV, and _____________________________________.A. This is unchanged with either excess NADH or NAD+B. Electron transfer is more favorable with excess NADH, yielding a more negative redox potentialC. Electron transfer is more favorable with excess NADH, yielding a more positive redox potentialD. Electron transfer is more favorable with excess NAD+, yielding a more negative redox potentialE. Electron transfer is more favorable with excess NAD+, yielding a more positive redox potential
Electron transfer is more favorable with excess NADH, yielding a more negative redox potential
Ubiquinone has a redox potential of +30 mV, while cytochrome c has a redox potential of +230 mV. In the electron transport chain, electrons flow from:A. Ubiquinone to cytochrome c.B. Cytochrome c to ubiquinone.
Ubiquinone to cytochrome c
Chlorophyll molecules absorb which color of light most strongly?A. Red lightB. Green lightC. Blue lightD. UV lightE. Fluorescent light
Identify the correct path of an electron during the photosynthetic electron transport chain in the thylakoid membrane.I. Photosystem III. Photosystem IIIII. NADPHIV. Ferredoxin-NADP reductaseV. Cytochrome b6-f complexVI. H2OVII. Plastoquinone
VI, II ,VII, V, I ,IV ,III
In photosynthesis, what drives ATP synthesis by ATP synthase?A. Transfer of high energy electrons to ATP synthaseB. Phosphorylation of ATP synthaseC. The absorption of a photon of light by an adjacent chlorophyll moleculeD. A proton gradient across the thylakoid membrane
A proton gradient across the thylakoid membrane
Which of the following is NOT a membrane-enclosed organelle in plant or animal cells?a. Peroxisomeb. Nucleusc. Endosomed. Chloroplaste. All of the above are membrane enclosed organelles
All of the above are membrane enclosed organelles
It is thought that eukaryotic cells developed membrane-enclosed organelles due to their:a. High plasma membrane surface area to cellular volume ratiob. Low plasma membrane surface area to cellular volume ratioc. Neither A nor B
Low plasma membrane surface area to cellular volume ratio
In the Ran-GTP/GDP nuclear transport system, which of the following statements is NOT true:a. The nuclear localization signal is located on the cargo protein destined for the nucleusb. Hydrolysis of GTP results in Ran-GDP dissociation from the nuclear transport receptor c. Binding of Ran-GTP to the nuclear transport receptor occurs in the cytosold. Hydrolysis of GTP occurs in the cytosole. All of the above are true
Binding of Ran-GTP to the nuclear transport receptor occurs in the cytosol
Suppose attaching GFP to a protein of interest is a popular method to study the localization, either cytosolic or nuclear, of that protein within a cell (it is). What does this method assume?a. The GFP sequence itself does not contain a nuclear localization signalb. GFP alone is a small enough protein to diffuse freely through nuclear poresc. GFP alone is a large enough protein to require active localization into the membrane d. A and Be. A and C
A and B
Start transfer sequences and stop transfer sequences are similar in that:a. Both are hydrophobicb. Both are hydrophilicc. Both are cleaved by signal peptidased. A and Ce. B and C
Both are hydrophobic
In the process of translocating a polypeptide across the membrane of the endoplasmic reticulum, a stop transfer sequence halts the process. What eventually becomes of the stop transfer sequence?a. It forms an α-helical membrane-spanning segment of the protein.b. It forms a β-barrel membrane-spanning segment of the proteinc. It is cleaved from the protein.d. It is translocated into the lumen of the endoplasmic reticulum.
It forms an α-helical membrane-spanning segment of the protein.
Proteins in the cytosol that are destined for other organelles must first enter the:a. The nucleusb. The endoplasmic reticulumc. The Golgi apparatusd. The lysosomese. The plasma membrane
The endoplasmic reticulum
Clathrin is a protein that:a. Coats vesicles budding from the golgi apparatus on the outward secretory pathwayb. Coats vesicles from the plasma membrane on the inward endocytic pathwayc. Both A and Bd. Neither A nor B
Both A and B
SNARE proteins are located on:a. Transport vesiclesb. Target membranesc. Both transport vesicles and target membranesd. Neither transport vesicles nor target membranes
Both transport vesicles and target membranes
In the endoplasmic reticulum, individual sugars are added one by one to a protein to create an oligosaccharide side chain.a. Trueb. False – oligosaccharides are added as a whole via a specialized lipidc. False – oligosaccharides are added as a whole via a specialized protein
False – oligosaccharides are added as a whole via a specialized lipid
Which type of protein binds to improperly folded or improperly assembled proteins in the ER, holding them there until proper folding occurs?a. Tethering proteinsb. Glycosylating proteinsc. Antibody proteinsd. SNARE proteinse. Chaperone proteins
Which mechanism is used for degrading entire organelles of a cell, such as a defective mitochondrion?a. Autophagyb. Apoptosisc. Phagocytosisd. Endocytosise. Ubiquitination
Which of these forms of cell-cell communication typically travels the longest distance from the originating cell to the target cell?a. Contact-dependent communicationb. Paracrine communicationc. Endocrine communicationd. Neuronal communication
Which of the following statements about steroid hormones is NOT correct?a. Steroid hormones include cortisol, estradiol, testosterone, and thyroxineb. The majority of steroid hormones pass through the plasma membrane due to their hydrophobic naturec. Steroid hormones bind intracellular hormone receptors which directly regulate transcriptional gene activation and repressiond. Each hormone binds a different hormone receptor and, in turn, activates and represses a unique set of target genese. All of the above are correct
All of the above are correct
Nitric oxide (NO) acts only on neighboring cells (as a local mediator in paracrine signaling) because:a. So little is produced by the signaling cell.b. It is rapidly washed away by the blood stream.c. It is rapidly converted to nitrates and nitrites in the target cell.d. It is rapidly converted to nitrates and nitrites in the extracellular fluid.
It is rapidly converted to nitrates and nitrites in the extracellular fluid.
Which of the following is NOT one of the basic classes of cell-surface receptors?a. Hormone receptorsb. G-protein-coupled receptorsc. Ion-channel-coupled receptorsd. Enzyme-coupled receptors
Which of the following statements about the inositol phospholipid signaling pathway is NOT true?a. The inositol phospholipid pathway is activated by GPCRs which activate the phospholipase C, a signaling molecule that also happens to be a phospholipidb. Phospholipase C cleaves the sugar-phosphate head off inositol phospholipid to generate IP3 and diacylglycerol (DAG)c. DAG remains embedded in the plasma membrane where it recruits protein kinase C (PKC)d. IP3 is released into the cytosol where it binds to and opens Ca2+ channels in the ER membranee. Binding of DAG to PKC requires cytosolic Ca2+f. All of the above are true
The inositol phospholipid pathway is activated by GPCRs which activate the phospholipase C, a signaling molecule that also happens to be a phospholipid
The concentration of free Ca2+ in the cytosol of an unstimulated cell is kept low compared with its concentration in both the extracellular fluid and the endoplasmic reticulum. Which of the following does not help maintain this difference?a. Membrane-bound Ca2+ pumps in the plasma membraneb. Ca2+-destroying enzymes in the cytosolc. Membrane-bound Ca2+ pumps in the ER membraned. Ca2+-binding proteins in the cytosole. All of the above maintain the concentration difference
Ca2+-destroying enzymes in the cytosol
Adaptation in signaling pathways allow a cell to remain sensitive to signals despite:a. Having mutant downstream adaptor proteins that may or may not bind the signaling receptorb. The slow speed of signal propagation upon stimulationc. The rapid speed of signal propagation upon stimulationd. The absence of second messengerse. Experiencing a wide range of background levels of stimulation
Experiencing a wide range of background levels of stimulation
Mutant Ras genes, which are found in approximately _______ of cancers, code for Ras proteins that are _____________________________________. a. 30%; constitutively activeb. 30%; constitutively inactivec. 80%; constitutively actived. 80%; constitutively inactivee. 80%; misfolded
30%; constitutively active
The cytoplasm of a eukaryotic cell is supported and spatially organized by a cytoskeleton of intermediate filaments, microtubules, and actin filaments.a. Trueb. False
Put the following components of the cytoskeleton in order of increasing diameter.a. Microtubules < Intermediate filaments < Actin filamentsb. Microtubules < Actin filaments < Intermediate filamentsc. Actin filaments < Microtubules < Intermediate filamentsd. Actin filaments < Intermediate filaments < Microtubulese. Intermediate filaments < Actin filaments < Microtubules
Which of the following is the main function of intermediate filaments?a. To provide tracks for guiding intracellular transportb. To enable cells to crawlc. To enable cells to withstand the mechanical stress that occurs when cells are stretched
To enable cells to withstand the mechanical stress that occurs when cells are stretched
At which level of the intermediate filament hierarchy is a covalent bond first found?a. The coiled-coil dimers are held together via covalent bondingb. The staggered tetramer of two coiled-coil dimers are held together via covalent bondingc. Two tetramers pack together via covalent bondingd. Eight tetramers twisted into a ropelike filament and are held together via covalent bondinge. None of the above interactions contains a covalent bond
None of the above interactions contains a covalent bond
Which of the following types of intermediate filaments are found in all animal cells?a. Keratinsb. Vimentin and vimentin-related filamentsc. Nuclear laminsd. Neurofilaments
Microtubule growing and shrinking, a process called ______________, stems from the intrinsic capacity of tubulin molecules to hydrolyze ____.a. Dynamic instability; ATPb. Rapid reassembly; ATPc. Dynamic instability; GTPd. Rapid reassembly; GTPe. Dynamic instability; either ATP or GTP
Dynamic instability; GTP
In a centrosome, which structures serve as nucleation sites for the formation of microtubules?a. αβ-tubulin dimersb. α- and β-tubulin monomersc. Tubulin protofilamentsd. γ-tubulin rings
Taxol, a drug used both as a cancer chemotherapy as well as in coating stents to prevent restenosis (recurrent narrowing of the coronary artery), is a mitotic inhibitor that works by:a. Binding to free tubulin molecules and preventing polymerizationb. Binding to microtubules and preventing polymerizationc. Binding to free tubulin and preventing de-polymerizationd. Binding to microtubules and preventing de-polymerizatione. None of the above
Binding to microtubules and preventing de-polymerization
In eukaryotic cells, directed intracellular movements are generated by motor proteins which use energy derived from repeated cycles of ATP hydrolysis to travel steadily, in a single direction, along either actin filaments or microtubules.a. Trueb. False – they only travel along microtubulesc. False – they only travel along actin filaments
The membrane of the Golgi apparatus is pulled toward the cell center by interacting with the motor protein:a. Dyneins that pull toward the plus endb. Dyneins that pull toward the minus endc. Kinesins that pull toward the minus endd. Kinesins that pull toward the plus ende. None of the above
Dyneins that pull toward the minus end
The hydrolysis of bound ATP to ADP in an actin filament _____ the strength of binding between monomers in the filament.a. Increasesb. Decreasesc. Has no effect on
Take the following figure where networks of microtubules (M.T.), actin filaments (A.F.), or intermediate filaments (I.F.) were exposed to a shear force and the resulting degree of stretch was measured. Which of the following statements is NOT true?a. Microtubules networks are easily deformed but cannot withstand excessive force without ruptureb. Intermediate filaments are easily deformed and can withstand large stresses and strains without rupturec. Actin filaments are less rigid than either microtubules or intermediate filamentsd. A, B, and C are all true
Actin filaments are less rigid than either microtubules or intermediate filaments
Which organelle sequesters Ca2+ inside muscle fibers?a. The nucleusb. Mitochondriac. The sarcoplasmic reticulumd. The Golgi apparatuse. Lysosomes
The sarcoplasmic reticulum
Below is the order of events of muscle contraction in terms of the actin-myosin interaction. Put the following transitional energetic events of muscle contraction (i – iv) in order.Attached ->Released ->Cocked ->Force-generating ->Attached
III, I, IV, II
Which is the correct order of the cell cycle?a. S ? G1 ? M ? G2 ? S …b. G1 ? M ? G2 ? S ? G1 …c. G1 ? S ? M ? G2 ? G1 …d. S ? G1 ? G2 ? M ? S …e. None of the above
None of the above
Given the cell cycle profile of proliferating, asynchronous cells as measured by flow cytometry, which of the following statements is NOT true?a. Inhibition of DNA synthesis would cause cells to accumulate in stage IIb. Inhibition of mitosis would cause cells to accumulate in stage IIIc. Stage I is the longest stage in the cell cycled. A, B, and C are correc
Inhibition of DNA synthesis would cause cells to accumulate in stage II
Different cyclin-dependent protein kinases (Cdks) trigger different stages of the cell cycle in part because:a. Their concentrations increase at different stages of the cycle.b. Their activities increase at different stages of the cycle due to cyclin concentrationsc. They are degraded at different stages of the cycle.d. A and Be. A, B and C
Their activities increase at different stages of the cycle due to cyclin concentrations
What is responsible for triggering DNA replication and ensuring that DNA replication is initiated only once per cell cycle?a. S-Cdkb. M-Cdkc. p21d. p53
DNA damage can arrest the cell at a checkpoint in G1 by activating an important checkpoint protein transcription factor known as __________ (which happens to be disrupted in ~50% of all cancer cases).a. G1/S-Cdkb. p21c. p53d. M-Cdke. Cdc25
Microtubules bind to replicated chromosomes (sister chromatids) and segregate them during anaphase. The ____________________ are the microtubules responsible for binding chromosomes, and they attach via the ________________ structure on a mitotic chromosome ?a. Aster microtubules; kinetochoreb. Kinetochore microtubules; kinetochorec. Interpolar microtubules; kinetochored. Aster microtubule; spindle polee. Kinetochore microtubules; spindle pole
Kinetochore microtubules; kinetochore
Which of the following is/are inherited randomly between daughter cells during cell division?a. Chromosomesb. Golgic. Soluble proteinsd. Both B and C are inherited randomlye. None of the above are inherited randomly
Which of the following statements regarding apoptosis is NOT true?a. Apoptosis involves activation of pro-caspases to active caspases, a family of proteases, and activation of caspases is primarily regulated by members of the Bcl-2 familyb. A cell undergoing apoptosis shrinks and condenses, and cellular DNA is broken into fragmentsc. Apoptotic cells often spill their contents into the surrounding region triggering the inflammation response of nearby cellsd. An intracellular apoptotic stimulus can cause activation of pro-caspase-9 via the release of cytochrome c from the mitochondrial intermembrane spacee. Apoptotic cells alter their membrane to attract phagocytic cells, which engulf the apoptotic cell
Apoptotic cells often spill their contents into the surrounding region triggering the inflammation response of nearby cells
Mitogens stimulate cell proliferation by:a. Phosphorylating the Rb proteinb. Activating the Rb proteinc. Inactivating the Rb proteind. A and Be. A and C
A and C
In mature organisms, cell number is controlled as a result of cell proliferation and cell death. An imbalance in the rates of proliferation or cell death can result in disorders of excessive cell accumulation, such as cancer, or disorders of excessive cell loss, such as neurodegenerative diseases.a. Trueb. False