Quizzes

1 and 3

Based on the figure below, cleavage at which two sites followed by DNA strand rejoining would lead to no change in the existing genetic information? 1 & 2 2 & 3 1 & 3 1 & 4

degraded by the proteasome.

If a protein is covalently modified by ubiquitin, it will be_________________. degraded by the proteasome. anchored to the plasma membrane. degraded by lysosomes. secreted by the proteasome.

50%

If one parent has Lynch syndrome, but the other does not, what is the likelihood that the child will also have Lynch syndrome? 100% 25% 10% 50%

Deamination of adenosine.

Inosine is formed by ______. Deamination of adenosine. Deamination of cytosine. Deamination of guanosine. demethylation of thymine.

three 13-bp repeats and four 9-bp repeats with enriched A-T base pairs.

Key component(s) of the E.coli OriC region is(are) _________. the RNA primer 20 subunits of A-T pairs three 13-bp repeats and four 9-bp repeats with enriched G-C base pairs. three 13-bp repeats and four 9-bp repeats with enriched A-T base pairs.

the transcription of genomic DNA.

Long noncoding RNA (lncRNA) is generated from______ the splicing of used mRNA. an infection of viral RNA. the transcription of genomic DNA. the tips of chromosomes.

1. Nucleotide-excision repair 2. direct repair 3. mismatch repair 4. Base-excision repair

Match the name of the DNA repair mechanism with the correct description. 1. Is needed to repair chemical damage in DNA affecting more than one nucleotide, such as cyclobutane pyrimidine dimers. 2. Repairs nucleotide bases without requiring DNA ligase. 3. Functions with DNA replication to remove incorrect nucleotides from the nascent strand. 4. Requires an endonuclease to remove an abasic nucleotide before DNA Pol I can replace a portion of the strand. mismatch repair Nucleotide-excision repair direct repair Base-excision repair

Largely conserved.

The DNA sequence of prokaryotic gene promoters are ______. Strong binders of DNA polymerase. Capable of binding different promoters. Distinct for each gene. Largely conserved.

mismatch DNA repair

The MutS-MutL-MutH protein complex is required for ____________. base excision DNA methylation DNA adenylation resolution of Holliday junctions. mismatch DNA repair

Helicase unwinds DNA and gyrase relieves the torsional strain.

What are the functions of enzymes helicase and gyrase in DNA replication? Gyrase adds the RNA primer and helicase removes it. Helicase synthesizes DNA and gyrase prevents helicase from dissociating. Helicase unwinds DNA and gyrase relieves the torsional strain. Gyrase synthesizes RNA primers and helicase.

disruption of transcriptional elongation by RNA polymerase

When the trp operon is attenuated, then _____ occurs. initiation of transcriptional initiation lac by RNA polymerase enhancement of transcriptional elongation by RNA polymerase initiation by RNA polymerase disruption of transcriptional elongation by RNA polymerase

dedifferentiated

iPS cells can be defined as ______ cells somatic stem dedifferentiated differentiated embryonic stem

1) Gln, 2) His, 3) False

1) If the trinucleotide sequence is CAG, which amino acid will be bound to the filter paper? 2) If the wobble position of the trinucleotide sequence is changed to a U, which amino acid will be bound to the filter paper? 3) True or False: Two distinct tRNA molecules with different anticodon sequences MUST be used to recognize the codons AGA and AGG. 1) Asp, 2) His, 3) True 1) Val, 2) Tyr, 3) False 1) Val, 2) Tyr, 3) False 1) Val, 2) His, 3) False 1) Gln, 2) His, 3) False 1) Val, 2) His, 3) True 1) Gln, 2) Tyr, 3) False 1) Gln, 2) His, 3) True 1) Asp, 2) His, 3) False

quadruplex DNA

A Holliday junction can best be defined as a region of__________________. DNA pyrimidine duplexes. quadruplex DNA. DNA damage. duplex DNA.

Methylation.

A common RNA base modification is ______. Methylation. Carboxylation. Hydroxylation. Amination.

plasma membrane

A lipid-modified protein is most likely localized to the ______. proteasome nucleus mitochondria plasma membrane

encodes a product that is easy to detect.

A reporter gene can be defined as a gene that_________________. encodes a product that is easy to detect. causes an epigenetic state. prevents protein synthesis. overproduces proteins.

Prevents new DNA from being replicated.

AZT is useful in the treatment of AIDS-HIV because it ______. Allows DNA to repair itself after viral DNA is added. Prevents HIV from binding to the cell. Prevents new DNA from being replicated. Allows DNA to be replicated at a slower rate.

5' ---> 3'

All DNA is synthesized in the ___________ direction. '3-->5' '5-->1' '1-->5' '5-->3'

It is not possible to predict the function from the sites since it could activate or repress at different sites.

Assume that you have identified all the cis-acting sites in a prokaryotic genome for a particular trans-acting transcription factor. What is the function of this transcription factor when binding to these sites? It is most likely a ligand-dependent repressor since the trp repressor uses this mode of regulation If the site has the sequence GATC-CTAG then it is an activator, if GATC-GATC then it is a repressor It is not possible to predict the function from the sites since it could activate or repress at different sites. It is most likely a ligand-dependent de-repressor since the lac repressor uses this mode of regulation. Assume that it is a repressor unless it requires cAMP and then assume it is an activator like CRP-cAMP.

5'-CGCUAUAGCGUUU-3'

Based on the sequence of the double stranded DNA shown above, which sequence below corresponds to the mRNA transcript? promoter 5' CGCTATAGCGTTT 3' 3' GCGATATCGCAAA 5' ------------------------- 5'-CGCTATAGCGTTT-3' 5'-AAAGCGAUAUCGC-3' 5'-UUUGCGAUAUCGC-3' 5'-GCGAUAUCGCAAA-3' 3'-CGCUAUAGCGUUU-5' 5'-GCGUAUAGCGAAA-3' 5'-CGCUAUAGCGUUU-3'

5'-AUG-3'

Both prokaryotes and eukaryotes recognize the mRNA sequence _____ as a translational start codon. 5'-GUA-3' 5'-CAU3' 5'-AUG-3' 5'-UAC-3"

one high density strand and one low density strand.

Conservative replication predicts that bacteria grown in 15N media for multiple generations, and then switched to 14N media for one generation, will have DNA strands of ___ a lower density. one high density strand and one low density strand. an intermediate density. a higher density.

Location of a DNA binding protein on DNA

DNA footprinting technique is used to identify the ___________________. Promotor region of a gene DNA sequence Location of a DNA binding protein on DNA Location of a gene in DNA

Produces photoproducts.

Excess exposure to ultraviolet light can cause DNA damage because it ______. Causes double strand breaks in DNA. Produces photoproducts. Causes protein misfolding. Produces methylated thymidine. Causes an abasic site to form.

Based on the number of known amino acids and the number of known nucleotide bases.

Francis Crick hypothesized that the Genetic Code must require 3 nucleotides in the mRNA to specify each amino acid based on a simple calculation. What was the logic behind this calculation? Choose the ONE best answer. Based on the number of known amino acids and the number of known tRNA molecules. Based on the fact that thymine is present in DNA but uracil is present in RNA, each of which base pairs with adenine. Based on the number of known amino acids and the number of known nucleotide bases. Based on the number of known tRNA molecules and the number of known nucleotide bases. 4 x 4 = 16, whereas 4 x 4 x 3 = 48, and since there are 20 amino acids, it must require 3 codons (48 > 16).

increased transcriptional activity

Histone acetylation leads to _________________ with regard to transcriptional regulation. repression of transcription repression of transcription increased transcriptional activity RNA interference

RNA tertiary structures are more dynamic than protein tertiary structures.

How are RNA structures different from protein structures? RNA can H-bond with itself, whereas proteins cannot. RNA is single stranded, whereas proteins are not. RNA tertiary structures are more dynamic than protein tertiary structures. RNA mutations can lead to non functioningnon functioning proteins, whereas protein mutations do not.

One of the strands is synthesized using Okazaki fragments.

How can antiparallel DNA strands (one and the other is ) be synthesized in such a way that the replication fork moves in only one direction? One of the strands is synthesized using Okazaki fragments. The antiparallel strands are not synthesized simultaneously. One strand is synthesized , whereas the other is . One of the strands is synthesized by RNA polymerase.

The chemical compound to be tested is added to a filter paper disk and placed on agar plates containing the tester Salmonella strain; potent mutagens result in MORE colonies forming on histidine free plates as compared to control plates. The Salmonella test strain used in the Ames test contains a mutation in the histidine biosynthetic pathway, which is used to identify compounds that induce back mutations to permit bacterial growth on histidine free plates.

How is the Ames test used to quantitate mutagenic potential of chemical compounds? Select the TWO best answers. Histone deficient plates are used to calculate the background mutation rate, which is the control plate for the filter disk experiment. The more colonies growing on the plate, the better the mutagen. The Ames test uses filter disks containing chemical compounds to quantitate the level at which the compound is lethal to the Salmonella tester strain; the FEWER colonies on the plate, the more toxic is the chemical regardless of mutagenic potential. The ratio of bacterial colonies to drug concentration (bc:dc) is used to calculate the mutagenic index of a chemical compound; high bc:dc ratios means the drug functions as a growth factor for the cells. The chemical compound to be tested is added to a filter paper disk and placed on agar plates containing the tester Salmonella strain; potent mutagens result in MORE colonies forming on histidine free plates as compared to control plates. The Salmonella test strain used in the Ames test contains a mutation in the histidine biosynthetic pathway, which is used to identify compounds that induce back mutations to permit bacterial growth on histidine free plates.

protein

If tRNAs are charged with radioactively-labeled amino acids in an in vitro system, then over time the radioactivity will be located in newly synthesized _________. mRNA codons aminoacyl tRNA synthetase protein

3

If the following mRNA was added to a cell-free translation system, how many unique protein sequences would be generated based on codon usage? 5'-ACCACCACCACCACCACCACCACCACCACCACCACC-3' 7 3 2 14

aminoacyl-tRNA

In the Nirenberg-Leder experiment, ________ was radioactively-labeled tRNA mRNA aminoacyl-tRNA ribosome

gyrase

In the figure shown below of an E. coli replication fork, which protein is responsible for relieving torsional stress caused by DNA unwinding? Single-stranded DNA binding protein Gyrase Helicase Primase

decreased ability to repair double-strand DNA breaks

Individuals with mutations of BRCA have increased incidence of cancer because of _________. increased ability to form pyrimidine dimers. increased ability to form methylated guanine. decreased ability to repair single-strand DNA breaks. decreased ability to repair double-strand DNA breaks

induction of the pluripotent state.

Introducing Genes encoding proteins Oct4, Sox2, c-Myc, and klf4 into a differentiated cell causes __________. Induction of cancer. Induction of apoptosis. induction of the pluripotent state. Induction cell meiosis.

1. Nucleotide-excision repair 2.Direct repair 3. Base-excision repair 4. Mismatch repair

Match the name of the DNA repair mechanism with the correct description Is needed to repair chemical damage in DNA affecting more than one nucleotide, such as cyclobutane pyrimidine dimers. Repairs nucleotide bases without requiring DNA ligase. Requires an endonuclease to remove an abasic nucleotide before DNA Pol I can replace a portion of the strand. Functions with DNA replication to remove incorrect nucleotides from the nascent strand.

hydrogen

One of the most common binding interactions between proteins and DNA are __________ bonds. ionic hydrogen polar covalent

B; D; C; A

Place the following steps in the correct order describing the steps required for synthesis of a membrane-bound protein. A. GTP binds to SRP. B. Protein synthesis occurs on the free ribosome. C. Protein synthesis halts. D. SRP binds to the signal peptide sequence. B; D; C; A D; C; B; A A; B; C; D A; B; D; C

C; A; B; D

Place the following steps in the elongation phase of mRNA translation into the proper order: A. Peptide bond formation occurs. B. GTP is hydrolyzed, and the ribosome moves one codon in the 3' direction. C. GTP is hydrolyzed, and EF-Tu*GDP is released. D. tRNA is released from the E site. A; B; C; D A; C; B; D C; A; B; D B; D; C; A

3,1,2,4

Put the following steps in the correct order to synthesize DNA. 1. Addition of an RNA primer 2. Extension of the RNA primer 3. Conversion of double-stranded DNA to single-stranded DNA 4. Synthesize new DNA 1; 2; 3; 4 2; 3; 4; 1 3; 1; 2; 4 4; 1; 3; 2

siRNA

RNA interference is mediated by ______ leading to mRNA degradation. miRNA siRNA snoRNA rRNA

Presence of a 2' OH group.

RNA is more susceptible to backbone hydrolysis than DNA because of the ______. Presence of a 3' OH group. Lack of thymine nucleotides. Presence of simpler nucleotides. Presence of a 2' OH group.

5'-CAG-3'

Radioactively-labeled aminoacyl-tRNA with the anticodon of 5'-CUG-3' was used in the Nirenberg-Leder experiment. They found that radioactivity was retained on the filter, which meant that _______________ was the sequence of the mRNA used in the experiment. 5'-GAC-3' 5'-CAG-3' 5'-GTC-3' 5'-CTG-3'

A specific region of the DNA is recognized and bound by the polymerases in both processes. The direction of enzyme movement on the template strand in both processes is 3' to 5'.

Select the two statements below that describe the similarities in DNA replication by DNA polymerase and RNA transcription by RNA polymerase in E.coli. The processes both include 3' to 5' exonuclease proofreading mechanism. A specific region of the DNA is recognized and bound by the polymerases in both processes. The processes both require a primer. The processes both require a sequence-specific DNA binding protein to initiate strand synthesis. The direction of enzyme movement on the template strand in both processes is 3' to 5'.

a RNA primer

The 3'-hydroxyl group used to initiate DNA synthesis comes from______________. H2O amino acids, always a RNA primer the magnesium ion uracils, always

16S; 30S

The Shine-Dalgarno sequence of mRNA base pairs with the _____ rRNA within the prokaryotic _____ ribosomal subunit. 16S; 50S 40S; 60S 16S; 30S 5S; 50S 23S; 30S

blocking the opening of helicase.

The Tus-Ter complex terminates DNA synthesis in E. coli by________________. methylating the DNA strand. breaking the single-strand DNA and preventing further synthesis. blocking the opening of helicase. forcing the primase to dissociate.

Replisome

The ____ contains the enzymes and proteins required to replicate DNA Polymerase DNA gyrase Replisome primase

Template

The ______ strand of DNA is transcribed into mRNA. Template Lagging Leading Coding

transfer of the signal peptide sequence into the translocon

The ______________ requires hydrolysis of GTP as a key step in the insertion of a newly synthesized protein into the ER lumen. transfer of the signal peptide sequence into the translocon release of SRP from the ribosome binding of SRP to the signal peptide sequence binding of SRP to the SRP receptor

Protein Synthesis

The antibiotics streptomycin, tetracycline, and chloramphenicol all interfere with____________. Protein Synthesis Cell Wall Formation Cell Membrane Formation Nucleic Acid Synthesis

Before the elongation phase

The bacterial sigma factor dissociates from the RNA polymerase ______. Before the elongation phase In the initiation phase During the elongation phase In the termination phase

binds to; causes conformational changes that affect

The best description of how allosteric regulation works is that a ligand __________ the transcriptional regulatory protein, which __________ the protein's affinity for DNA. covalently modifies; increases binds to; causes conformational changes that can only decrease covalently modifies; decreases binds to; causes conformational changes that affect

transcriptional initiation.

The control point for prokaryotic gene regulation primarily occurs at the point of ____________. transcriptional initiation. translational initiation. genetic recombination. mRNA processing.

negative; reaches a steady state of expression.

The figure below shows __________ autoregulation and that __________. positive; will not be expressed in the absence of an activator. negative; reaches a steady state of expression. negative; will not be expressed in the absence of an activator. positive; reaches a steady state of expression.

stimulate; bind tighter

The function of CRP in lac operon expression is to __________ the promoter by causing RNA polymerase to __________. stimulate; bind tighter stimulate; dissociate inhibit; dissociate inhibit; bind tighter

keep the Pol III complex associated with the DNA.

The function of the beta-clamp in DNA replication is to_____________. separate the DNA into a single strand. keep the torsional strain reduced. add the RNA primer. keep the Pol III complex associated with the DNA.

the enzymes needed to utilize the disaccharide lactose.

The function of the lac operon is to provide_________________. the enzymes needed to produce lactose. the ability to distinguish glucose from galactose. the enzymes needed to utilize the disaccharide lactose. beta-lactamase to inhibit penicillin.

Requires many more transcription factors than prokaryotic transcription.

The initiation of transcription in eukaryotes ______. Uses RNA polymerase as well as helicase and primase. Requires the complete unfolding of the gene into single-stranded DNA. Requires many more transcription factors than prokaryotic transcription. Occurs in the same manner as prokaryotic transcription.

Linear versus lariat intron products

The main difference between group I and group II introns is ______. Intron cleaving versus exon ligating abilities Linear versus lariat intron products Nucleophilic versus electrophilic hydroxyl attacks Cis versus trans cleaving capabilities

dicer

The name of the enzyme responsible for generating siRNA is ______________. Dicer Interfase RNAse Telomerase

is separated into single strands before replications.

The original duplex DNA template ___________________ in semiconservative DNA replication. can only be replicated once. is separated into single strands before replications. remains intact to make a new DNA duplex. is broken into fragments.

recruit other transcription factors to the gene promoter.

The primary function of transcriptional activator proteins is to _____. recruit other transcription factors to the gene promoter. recruit gene promoters to the regulatory site. initiate DNA synthesis.trp op initiate RNA synthesis.

Stabilize the negative charges on

The role of Mg2+ in DNA replication is to __________ the incoming deoxynucleotide Act as a nucleophile to attack the a-phosphoryl group in Stabilize the negative charges on Stabilize the positive charges on Protonate

bind mRNA and facilitate the splicing reaction.

The roles of U1, U2, U4, U5, and U6 in the spliceosome complex are to________________. carry the products from the nucleus to the cytoplasm. bind the small nuclear RNA. bind mRNA and facilitate the splicing reaction. bind proteins and hold the complex together.

octamer

Together, the eight histone molecules are called the histone ________________. dimer. octane. tetramer. octamer.

Active site geometry ensures that only correct sized nucleotide base pairs are formed, and 3' to 5' proofreading removes incorrect nucleotides.

What accounts for the high fidelity of DNA polymerization? Active site geometry but not nucleotide proofreading is important to the high fidelity of DNA polymerization. Active site geometry ensures that only correct sized nucleotide base pairs are formed, and 3' to 5' proofreading removes incorrect nucleotides. The 5' to 3' exonuclease proofreading activity removes nucleotides, which provides a mechanism to correct errors at the fork. Nucleotide excision repair corrects all DNA replication errors, so DNA polymerase does not need a proofreading activity.

HAT activates the gene and HDAC represses the gene.

What are the functions of the HAT and HDAC enzymes with regard to regulating gene expression in eukaryotic cells? Both HAT and HDAC activate the gene. HAT represses the gene and HDAC activates the gene. Both HAT and HDAC repress the gene. HAT activates the gene and HDAC represses the gene.

somatic and embryonic

What are the two main types of stem cells? stromal and somatic genetic and epigenetic somatic and embryonic somatic and epithelial stromal and embryonic

Genes can contain more than one polyadenylation site, which alters the 3' of the mRNA transcript and the inclusion/exclusion of exons. mRNA transcripts from the same gene can be differentially spliced to include/exclude exons.

What explains the observation that a single eukaryotic protein coding gene can give rise to multiple different proteins, i.e., why are there only ~25,000 human genes in the genome, but ~150,000 different proteins in the human "proteome?" Choose the TWO best answers Some genes are transcribed from both strands of the DNA and this generates isozymes of the same protein. Serine phosphorylation of a polypeptide changes its amino acid sequence, and thereby generates multiple proteins from the same gene. Genes can contain more than one polyadenylation site, which alters the 3' of the mRNA transcript and the inclusion/exclusion of exons. mRNA transcripts from the same gene can be differentially spliced to include/exclude exons. Polypeptide subunits of the same protein complexes are often differentially cleaved by protease enzymes, resulting in loss of some subunits and duplication of others.

It synthesizes DNA on the lagging strand at the ends of chromosomes.

What is the function of the enzyme telomerase in eukaryotic DNA synthesis? It synthesizes DNA on the lagging strand at the ends of chromosomes. It binds to single-strand DNA to prevent refolding of the telomere. It removes the telomeres from the ends of chromosomes. It shortens the telomeres after each round of DNA replication. It synthesizes DNA on the leading strand at the ends of chromosomes.

abasic

When a cytosine is deaminated to form uracil and removed by glycosylase enzymes, a(n) _________ site is generated. deaminated dibasic abasic nonbasic

inhibition of transcriptional initiation

When the Trp repressor is bound to the trp operon, it results in the __________ by RNA polymerase. enhancement of transcriptional elongation initiation inhibition of transcriptional initiation disruption of transcriptional elongation

is inhibited

When there is no lactose in a cell, transcription of the lac operon _____. is stimulated is activated but only when glucose levels are high is inhibited production of lac operon does not depend on lactose concentration

Trp repressor is bound to DNA.

When tryptophan levels inside a bacterial cell are elevated then _________________. There is initiation of RNA polymerase. Trp repressor is not bound to DNA. Trp repressor is bound to DNA. transcriptional elongation by RNA polymerase is enhanced.

A

Where would an amino acid be attached to the tRNA below? A B C D

mismatch repair

Which DNA repair mechanism is required to fix replication errors in E. coli? abasic repair mismatch repair degrading of the entire DNA strand to start over base excision

lysine

Which amino acid residues on histones are acetylated? arginine serine lysine histidine

DNA primase

Which enzyme synthesizes the RNA primer for DNA replication? DNA primase DNA polymerization DNA polymerase DNA Pol III

Group I introns use an exogenous guanosine as a cofactor.

Which of the following statements is correct regarding self-splicing introns? Group I introns form a lariat structure. Group I introns are found across all organisms, including vertebrates. Group I introns use an exogenous guanosine as a cofactor. Group II introns use an exogenous guanosine as a cofactor.

The spliceosome mechanism involves two transesterification reactions.

Which of the following statements is correct regarding spliceosome-mediated trans splicing? The snRNPs involved in splicing are not recycled. The spliceosome mechanism closely resembles the mechanism of group I introns. The spliceosome mechanism involves two transesterification reactions. The spliceosome is composed only of proteins.

Trans-acting factors can bind to specific DNA sequences whereas cis-acting sites are DNA sequences.

Which statement below most accurately describes the function of trans- and cis-acting factors in mediating gene regulation? Trans-acting factors can bind to specific DNA sequences whereas cis-acting sites are DNA sequences. Cis-acting factors can bind to specific DNA sequences whereas trans-acting sites are DNA sequences. Trans- and cis-acting factors can both bind to specific DNA sequences. Trans- and cis-acting factors can both only bind to DNA elements to which they are physically linked.

Spontaneous cytosine deamination generates uracil, which base pairs with adenine during replication, and thereby converts a C-G base pair to a T-A base pair.

Why does RNA contain uracil and DNA contain thymine? Choose the ONE best answer to this question. Spontaneous cytosine deamination generates uracil, which base pairs with adenine during replication, and thereby converts a C-G base pair to a T-A base pair. RNA transcription base pairs U-T in the RNA with DNA, whereas this process base pairs A-T in the RNA with DNA. Therefore, if uracil were present in DNA, then U-A and A-U could not be distinguished. Uracil specifies RNA polymerization, and therefore, if uracil is inserted into DNA, then RNA polymerization will occur on DNA strands. Loss of NH3 from cytosine generates uracil, which base pairs with thymine and causes damage in DNA. If deamination of thymine generated guanine, then this would not be a problem. DNA damage can alter the nucleotide bases and cause mutations that cannot be repaired if the base is uracil since repair enzymes recognize thymine in DNA, not uracil.

Ribosomal RNA

____________is directly involved in protein synthesis. Long non-coding RNA Ribosomal RNA Short interfering RNA Small nuclear RNA

Charged with an amino acid

tRNA is _____ before binding to the ribosome to allow for translation to occur. Charged with an anticodon Charged with a codon Bound by ATP Charged with an amino acid