cell bio exam 1
Which of the following statements concerning electron microscopy (EM) is NOT true?
The resolution of the best light microscopes is better than that of electron microscopes
Concerning the chemistry of molecules, which of the following statements is false?
The amino acid proline can readily be found in -helices and -pleated sheets.
Which of the following amino acids would be buried in the interior portion of a globular protein?
Valine
Which of the following amino acids would be expected to be found at the end of -helices and -sheets, due to their kinked conformation that prevents them from participating in these types of secondary structures?
proline
Which of the following are considered as coenzymes to facilitate enzyme activity?
vitamin C and FAD
During eukaryotic DNA replication and repair, DNA polymerase _____ is involved in the replication of mitochondrial DNA, while DNA polymerase ___ is associated with the primase complex.
y-alpha
Given the Lineweaver-Burk plot, for the uninhibited enzyme you have the following values: X-intercept of -8 and Y-intercept of 0.2. Calculate the corresponding KM for the uninhibited enzyme.
0.125
What protein adds the -clamp to newly primed DNA on the lagging strand so that DNA polymerase III can begin synthesis of the next Okazaki fragment?
-clamp loader
Calculate the corresponding K M for the uninhibited enzyme.
0.25
Given the Lineweaver-Burk plot, for the uninhibited enzyme you have the following values: X-intercept of -4 and Y-intercept of 0.25. Calculate the corresponding V max for the uninhibited enzyme.
4
Given the Lineweaver-Burk plot, for the uninhibited enzyme you have the following values: X-intercept of -8 and Y-intercept of 0.2. Calculate the corresponding Vmax for the uninhibited enzyme.
5
Bacterial DNA polymerase I exhibits what type of activity that is lacking in DNA polymerase III?
5' to 3' exonuclease activity
Bacterial DNA polymerase III exhibits what type of activities?
5' to 3' polymerase activity 5' to 3' exonuclease activity
The K M of a reaction is defined by which of the following?
A measure of the affinity of the enzyme for the substrate under some conditions B) A measure of the substrate concentration at exactly one-half of V Max C) A kinetic value that can be determined from Lineweaver-Burk plots of enzyme velocities
What type of DNA repair utilizes proteins that scan DNA sequences as shown in the figure, recognize base alterations and cleave the base from the sugar?
Base excision repair
Which of the following approaches can use antibodies to determine protein-protein interactions?
Co-immunoprecipitation
Vitamins are an example of a ______. The iron atom of a heme group is an example of a ______.
Coenzyme, Cofactor
Given the Lineweaver-Burk plot for increasing concentrations of an inhibitor, what is the nature or type of inhibitor used in this experiment?
Competitive inhibitor
Which of the following amino acids can form disulfide bonds to stabilize the tertiary structure of a protein?
Cysteine
In terms of DNA structure and composition, which of the following is not true?
DNA strands of the double helix run parallel to each other
In bright-field microscopy, which of the following will increase the resolution (i.e. smaller value for d) of your compound microscope?
Decreasing wavelength; increasing the numerical aperture
You are a virologist interested in studying the evolution of viral genomes. You are studying two newly isolated viral strains and have sequenced their genomes. You find that the genome of strain 1 contains 25% A, 45% G, 20% C, and 10% T. You report that you have isolated a virus with a single-stranded DNA genome. Based on what evidence can you make this conclusion?
Double-stranded genomes have equal amounts of A and T
You are a virologist interested in studying the evolution of viral genomes. You are studying two newly isolated viral strains and have sequenced their genomes. You find that the genome of strain 1 contains 25% A, 45% G, 20% C, and 10% T. You report that you have isolated a virus with a single-stranded DNA genome. Based on what evidence can you make this conclusion?
Double-stranded genomes have equal amounts of A and T
Which of the following statements is false?
Enzymes lower the free energy released by the reaction that they facilitate.
. Which of the following statements is false?
Enzymes raise the activation energy for a specific reaction.
With respect to protein structure, which of the following statements is false?
Fibrous proteins tend to have a lot of -helical structure, whereas globular proteins tend to have predominantly -pleated sheet structure.
If you are studying the expression of GFP in a sample of transgenic flies that express a histone-GFP reporter, which type of microscope would you use?
Fluorescence microscope
Methodology used to locate the position of a gene or sequence along a chromosome.
Fluorescent in situ hybridization
If you wanted to do a two-step protein purification sequentially using two columns based first on size and then on charge, you would do __________ followed by __________.
Gel filtration chromatography; ion exchange chromatography
Which of the following statements concerning molecular techniques is NOT correct?
Genomic libraries can be used to examine differences in tissue/organ-specific gene expression.
Concerning protein structure and function, which of the following is true?
Globular proteins are primarily comprised of alpha -helices
ΔG° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is energetically favorable, i.e. spontaneous?
Glucose 1-phosphate Glucose 6-phosphate ΔG° = -1.7 kcal/mole Glucose CO2 + H2O ΔG° = -686 kcal/mole
Hemoglobin is the best-studied multisubunit protein. What term best describes its composition?
Heterotetramer
With respect to genome structure and stability, all of the following statements are true except:
Histone genes are found in the non-repeated fraction of eukaryotic DNA.
In mammalian cells, high energy sources can induce double stranded breaks in the DNA duplex to stimulate repair. Which of the following repair mechanisms would ensure the greatest chance of not introducing mutations at the repair site?
Homologous recombination
Which non-covalent interactions stabilize the alpha-helical and beta-pleated sheets of proteins?
Hydrogen bonds
In bright-field microscopy, which of the following will decrease the resolution (i.e. larger value for d) of your compound microscope?
Increasing wavelength; decreasing the numerical aperture
Enzyme catalysis mechanism that utilizes a change in the conformation of the substrate to bring it closer to the conformation of the transition state.
Induced strain
The _______ provides a functional network association based on protein-protein interactions that occur in a cell, while the _________ represents the entire protein content in a cell. Proteins that have the most associations are referred to as ______ proteins.
Interactome; Proteome; Hub
If the normal gene order on a chromosome is changed to the order shown on the bottom of the figure to the right, what type of structural variation does this represent?
Inversion
If you wanted to do a two-step protein purification, (sequentially using two columns) based first on charge and then on size, you would do __________ followed by __________.
Ion exchange chromatography; gel filtration chromatography
Which non-covalent bond has the most amount of energy associated with them?
Ionic bonds
What is the chemical nature of the primer that is referred to by the arrow?
It is an RNA primer.
Which statement about the newly synthesized strand of a human chromosome is true?
It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis.
You have discovered an "Exo - " mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged. Which of the following properties do you expect the mutant polymerase to have?
It will be more likely to generate mismatched base pairs.
ou have discovered an "Exo-" mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged. Which of the following properties do you expect the mutant polymerase to have?
It will be more likely to generate mismatched base pairs.
in bacterial replication, what is the function of primase?
Lays down an RNA primer needed for replication
Which of the following amino acids can form ionic bonds?
Lysine
in bacteria, post-replicative mismatch repair of incorrectly added nucleotides after DNA replication is dependent on the detection of which of the following?
Methylation of parental DNA strand
These proteins are "helper proteins" that prevent nonselective interactions during protein folding so that newly formed proteins can achieve their proper 3D conformation.
Molecular chaperones
Which of the following statements concerning DNA is true?
Most proteins interact with DNA along its major groove.
What of the following mutations at Glu 35 of the Lysozyme enzyme would you predict to be the least likely to have a deleterious effect on enzymatic activity?
Mutating it to Asp
Which of the following tripeptides would be able to undergo post-translational modification?
N - serine - threonine - tyrosine - C
In mammalian cells, high energy sources can induce double stranded breaks in the DNA duplex to stimulate repair. Which of the following repair mechanisms generally involves the introduction of small deletions after repair is completed?
Non-homologous end joining
in mammalian cells, what double-stranded DNA break repair mechanism relies on the activity of Ku proteins, DNA-PKCS, and DNA ligase?
Non-homologous end joining
Which amino acids would most likely reside in the membrane-anchoring domain of a membraneembedded protein?
Nonpolar amino acids
In terms of DNA structure and composition, which of the following is true?
Nucleotides of a DNA strand are linked by 3',5'-phosphodiester bonds
During eukaryotic DNA replication, CAF-1 mediates the immediate histone packaging of DNA based on its interaction with which protein in the replication complex?
PCNA
The major cellular macromolecules include which of the following?
Proteins, lipids, nucleic acids, and carbohydrates
What would the highest level of organization be for a ribosome?
Quaternary
Which of the following amino acids can form hydrogen bonds?
Serine
Enzyme catalysis mechanism that utilizes appropriate positioning of two substrate molecules within the active site so that the transition state is achieved more readily.
Substrate Orientation
In thermodynamics, what expression refers to the loss of available energy to the system?
T delta S
Concerning the chemistry of molecules, which of the following statements is false?
The energy to overcome Van der Waals forces, in terms of kcal/mol, is greater than the energy needed to break hydrogen bonds.
A certain inhibitor of an enzymatic reaction was determined to act as a competitive inhibitor. Which of the following statements about the inhibitor is true?
The inhibitor increases K M , but has no effect on VMax
Which of the following statements concerning DNA is true?
The melting temperature of DNA increases as its GC content increases
You create a recombinant DNA molecule that fuses the coding sequence of green fluorescent protein to the regulatory DNA sequences that control the expression of your favorite gene. Which of the following pieces of information can you NOT gain by examining the expression of this reporter gene?
The specific location within the cell of the protein encoded by this gene
You create a recombinant DNA molecule that fuses the coding sequence of green fluorescent protein to the regulatory DNA sequences that control the expression of your favorite gene. Which of the following pieces of information can you NOT gain by examining the expression of this reporter gene?
The specific location within the cell of the protein encoded by this gene
Human cells contain several different proteins that bind calcium. They share similar amino acid sequences but are found expressed in different cell types. What can you infer about the genes for these proteins?
They probably arose in evolution by gene duplication
Which of the following statements is not an accurate statement about thymine dimers?
Thymine dimers are covalent links between thymidines on opposite DNA strands.
The DNA duplex consists of two long covalent polymers wrapped around each other many times over their entire length. The separation of the DNA strands for replication causes the strands to be "overwound" in front of the replication fork. How does the cell relieve the torsional stress created along the DNA duplex during replication?
Topoisomerases break the covalent bonds of the backbone allowing the local unwinding of DNA ahead of the replication fork.
With respect to genome structure and stability, all of the following statements are true except:
Transposons have an RNA intermediate and require reverse transcriptase.
Where would DNA polymerase III be able to add nucleotides in the growing DNA strands during DNA replication, as illustrated in the accompanying figure for bacterial DNA replication?
all the 3 prime ends
What would be considered examples of protein secondary structure?
alpha-helices beta-pleated sheets Hinges, loops, or turns
What is the identity of the protein to which the arrows are referring in the figure to the right? One of the functions of this protein is to direct DNA polymerases to newly primed DNA strands.
beta-clamp
Protein-based diseases (e.g. prions, Alzheimer's' disease) arise from the excessive presence of what kind of protein secondary structure, making the proteins more fibrous than globular.
beta-pleated sheets
In thermodynamics, what expression addresses whether a reaction will be spontaneous?
delta G
