LS 3 Final Khankan - Launchpad Quizzes

Chromatin is composed of: protein. RNA and protein. DNA and protein. DNA and RNA. DNA.

DNA and protein.

When using genomic DNA that was digested with a restriction enzyme and ligating the product of this reaction into plasmids that were also cut with the same restriction enzyme, what type of product will you get? DNA library this reaction would not work plasmids containing a gene of interest cDNA library

DNA library

What must be bound to the small subunit of the ribosome in order for it to bind to the start codon of the mRNA molecule? IF-2-GTP and IF-3 IF-3 and IF-1 IF-1 and IF-2-GTP IF-3 and fMET tRNA fMET tRNA and IF-1

IF-3 and IF-1

The CRISPR/Cas9 system is able to target (and then cleave) invading phage DNA using: a randomly generated DNA sequence complementary to part of that phage DNA and bound to Cas9. DNA complementary to part of that phage DNA and bound to Cas9. machinery that recognizes all foreign DNA. a randomly generated RNA sequence complementary to part of that phage DNA and bound to Cas9. RNA complementary to part of that phage DNA and bound to Cas9.

RNA complementary to part of that phage DNA and bound to Cas9.

Which enzyme is important in the resolution of a Holliday junction? Resolvase Polymerase Helicase Recombinase Nuclease

Resolvase

How do eukaryotic transcription factors exert their effects on transcription when their binding sites can be thousands of base pairs away from the promoter? Once bound to the site, the regulatory protein catalyzes the formation of an effector molecule that then travels to and binds the polymerase. Regulatory proteins bind the sequences and then slide along the DNA until they reach an RNA polymerase bound to a promoter. The DNA between the bound site and the polymerase-promoter complex loops out, increasing proximity. After binding to the site, the regulatory protein releases the DNA and is targeted to the polymerase via coactivator proteins.

The DNA between the bound site and the polymerase-promoter complex loops out, increasing proximity.

Why is it necessary to incorporate the invading viral DNA into the bacterial genome? This prevents infection from the invading virus. The invading viral DNA is not incorporated into the genome. This is the only way the virus can transcribe and translate its DNA for infection. The bacterium can now transcribe the section of the viral gene to create CRISPR/Cas9 complexes. This causes the viral DNA to be degraded.

The bacterium can now transcribe the section of the viral gene to create CRISPR/Cas9 complexes.

Which of the following statements about the bacterial ribosome is NOT true? The 70S ribosome is a complex of 50S and 30S subunits. The entire protein component of the 30S subunit is a single polypeptide chain. Each ribosomal subunit contains at least one RNA molecule. An rRNA molecule, rather than protein, catalyzes peptide bond formation.

The entire protein component of the 30S subunit is a single polypeptide chain.

Which of the following is NOT true of the lac operon? The operator region regulates transcription through interaction with the Lac repressor protein. The lacI gene is controlled from the same promoter as the lacZ gene. Transcription produces a single polycistronic mRNA containing the lacZ, lacY, and lacA genes. The Lac repressor protein is constitutively expressed.

The lacI gene is controlled from the same promoter as the lacZ gene.

The prokaryotic ribosome consists of a 40S and a 50S subunit a 30S and a 60S subunit a 40S and a 60S subunit a 30S and a 50S subunit

a 30S and a 50S subunit

A eukaryotic genome is defined as: a haploid set of chromosomes plus one copy of any organelle DNA present. all of the DNA in a cell. a haploid set of chromosomes. a diploid set of chromosomes. a diploid set of chromosomes plus one copy of any organelle DNA present.

a haploid set of chromosomes.

Each nucleosome contains: four proteins: SMC1, SMC2, SMC3, and SMC4. a histone octamer composed of two copies of each of the following proteins: H1, H2, H3, and H4. four proteins: H2A, H2B, H3, and H4. a histone octamer composed of two copies of each of the following proteins: H2A, H2B, H3, and H4. a mixture of histone and SMC proteins.

a histone octamer composed of two copies of each of the following proteins: H2A, H2B, H3, and H4

Below are some events that occur in the process of translating mRNA into a protein in a bacterial cell. Which events require an input of energy? 1. EF-G-GTP binds to the tRNA in the A site and causes the tRNA to advance to the P site. 2. The rRNA in the ribosomal 30S subunit base-pairs with the Shine-Dalgarno sequence in the mRNA. 3. Peptide bond forms between the growing amino acid chain in the P site and the new amino acid in the A site. 4. IF-3 binds in the E site. 5. RRF binds in the A site. 6. RF-1 or -2 binds in the A site. 7. Ribosomal complex dissociates. 8. Peptide chain dissociates from final tRNA. 9. fMET tRNA binds to the start codon in the mRNA. 10. RF-3-GTP causes displacement of RF-1 or -2 and its exit from the ribosome. 11. EF-G-GTP binds to the A site and causes RRF to shift to the P site. 12. A conformational change in the 30S subunit allows the 50S subunit to bind, forming the 70S ribosome. 10, 6, 3, 12 11, 10, 1, 12 1, 5, 10, 8 3, 11, 7, 4 4, 9, 8, 5

11, 10, 1, 12

Below are some events that occur in the process of translating mRNA into a protein in a bacterial cell. Select the answer that best represents the order in which they occur. 1. EF-G-GTP binds to the tRNA in the A site and causes the tRNA to advance to the P site. 2. The rRNA in the ribosomal 30S subunit base-pairs with the Shine-Dalgarno sequence in the mRNA. 3. Peptide bond forms between the growing amino acid chain in the P site and the new amino acid in the A site. 4. IF-3 binds in the E site. 5. RRF binds in the A site. 6. RF-1 or -2 binds in the A site. 7. Ribosomal complex dissociates. 8. Peptide chain dissociates from final tRNA. 9. fMET tRNA binds to the start codon in the mRNA. 10. RF-3-GTP causes displacement of RF-1 or -2 and its exit from the ribosome. 11. EF-G-GTP binds to the A site and causes RRF to shift to the P site. 12. A conformational change in the 30S subunit allows the 50S subunit to bind, forming the 70S ribosome. 3, 6, 10, 5, 7 12, 1, 10, 11, 8 12, 9, 2, 3, 6 4, 8, 3, 11, 7 9, 3, 5, 10, 6, 7

3, 6, 10, 5, 7

If a DNA fragment is 21,000 bp long, about how many DNA fragments would result after incubation with EcoRI? 3 5 100 10 20

5

In the repair of a collapsing DNA replication fork, which process is correctly paired with the enzyme active at that step? Strand invasion — helicase Holliday intermediate resolution — nuclease Branch migration — resolvase Branch migration — ligase 5'-end processing — nuclease

5'-end processing — nuclease

Which of the following is a CORRECT pairing of a base to the product of its deamination? adenine → xanthine thymidine → uracil 5-methylcytosine → thymine cytosine → thymine guanine → hypoxanthine

5-methylcytosine → thymine

a new peptide bond is formed between these two sites in the ribosome: P and E A and P A and E

A and P

a new aminoacyl-tRNA enters the ribosome through this site P site A site E site

A site

Which DNA lesion is repaired by mismatch repair? Pyrimidine dimer C≡G O6-methylguanine-C Benzo[a]pyrene-guanine-C A-G

A-G

Which of the following is NOT an essential component of the bacterial elongation stage of translation? functional 70S ribosome EF-Ts aminoacyl-tRNAs ATP

ATP

If a CRISPR/Cas9-like immune system existed naturally in humans, as well as in bacteria, what would you search for as indications of such a system? Known viral sequences inserted in the human genome Clusters of repeated sequences with homology to infectious agents in the human genome Small untranslated RNAs with short areas of homology to infectious agents A protein with homology to Cas9 All of the above.

All of the above.

Which type(s) of mutation can be created using the CRISPR/Cas9 system? Deletion of a splicing enhancer of a gene Point mutations in the coding region of a gene Excision of enhancer sites that lie at a distance downstream and upstream of a gene Deletion of a single codon in the coding region of a gene All of these answer choices are correct.

All of these answer choices are correct.

A pyrimidine dimer can be repaired by which mechanism? Nucleotide excision repair Mismatch repair Base excision repair Photorepair Both nucleotide excision repair and photorepair

Both nucleotide excision repair and photorepair

The CRISPR/Cas9 system has been transferred to mammals and other animals and used to edit genes. This is possible for all of the following reasons except the following: CRISPR/Cas9 allows very specific sequence replacement. CRISPR/Cas9 is able to override the immune systems of these animals. Biomolecules—RNA, DNA, proteins—work in virtually the same manner in all organisms. CRISPR/Cas9 can be easily inserted into animal cells. Eukaryotic cells have DNA repair mechanisms that CRISPR/Cas9 can take advantage of.

CRISPR/Cas9 is able to override the immune systems of these animals.

What kind of lesion would a base excision repair fix? Benzo[a]pyrene-guanine-C Double-strand DNA breaks C-A Pyrimidine dimers Cytosine deamination

Cytosine deamination

In a bacterium, the guide RNA in the CRISPR/Cas9 system originates from: DNA from the bacterial genome. DNA from an invading pathogen. RNA from the bacterial genome. RNA from an invading pathogen. a DNA-RNA hybrid created by researchers.

DNA from an invading pathogen.

Why is the ground state of gene expression in EK repressed? Choose the best answer mediator needs to bind the RNA polymerase histones have to be acetylated for transcription to occur DNA is organized and compacted into chromatin there are always repressors present

DNA is organized and compacted into chromatin

How do trinucleotide repeats expand? RNA polymerase slips during translation DNA polymerase slips during replication DNA polymerase incorporates more of the trinucleotide into the parental strand the repeat is expanded through the MMR system

DNA polymerase slips during replication

Once one CRISPR/Cas9 molecule is made against an invading pathogen, it is active against all invading pathogens. True False

False

To terminate translation, a special tRNA recognizes the stop codon of the mRNA and binds in the A site of the ribosome. True False

False

Which of the following is NOT true of genomic and cDNA libraries? cDNA libraries only contain sequences from transcribed genes. Genomic libraries usually contain large fragments and are likely to be constructed in YAC or BAC vectors. cDNA libraries contain cDNAs made from mRNA. Genomic libraries contain fragments of genomic DNA that are generated by partial digests with restriction enzymes. Genes represented in cDNA libraries contain control sequences that direct transcription.

Genes represented in cDNA libraries contain control sequences that direct transcription.

The action of which of the following enzymes leads to chromatin de-compaction? DNMT (DNA methyl transferase) HAT (Histone acetyl transferase) HMT (Histone methyltransferase) HDAC (Histone deacetylase)

HAT (Histone acetyl transferase)

Which initiation factor is responsible for recycling ribosomes? IF-3 IF-2-GDP IF-3 + ATP IF-2-GTP IF-1

IF-3

Which of the following is NOT true of the lacI region of the lac operon? It is transcribed separately from the operon. Its mutation leads to constitutive expression of the operon. It is bound by the Lac repressor when lactose is unavailable. It produces a diffusible product that can regulate the expression of the operon.

It is bound by the Lac repressor when lactose is unavailable.

Which of the following BEST explains why not all individual aminoacyl-tRNA synthetase enzymes recognize the correct tRNA molecules through the anticodon sequence? All tRNA molecules have the same anticodon sequence. Synthetases only contact the tRNA molecules at the 3′-terminal hydroxyl. More than one codon may code for one amino acid. There are 61 different aminoacyl-tRNA synthetase enzymes.

More than one codon may code for one amino acid.

Which of the following repair pathways can lead to deletions of damaged regions? NER HDR MMR NHEJ

NHEJ

Which method was described in the video on sequencing the human genome? Microarray Next generation sequecing Sanger sequencing ChIP

Next generation sequecing

What kind of DNA repair mechanism is used to repair large, bulky lesions? Repair of methylated nucleotide bases Mismatch repair Photorepair Nucleotide excision repair Base excision repair

Nucleotide excision repair

As in the simulation, you attempt to edit a mouse genome to produce a mottled mouse, yet the mouse that you edited still has black fur like its parents. Why did this mouse not have the mottled phenotype you engineered? Mottled fur is a dominant trait, so you would have to wait for the offspring of the engineered mouse to see the desired phenotype. The CRISPR/Cas9 system cannot be used successfully in mammals, so you would not see any mottled mice. One or both of the guide RNAs did not cut either allele of the target gene. You have to edit both alleles of the gene; otherwise, you will not see the mottled phenotype. The skin color gene was edited in the wrong cell type.

One or both of the guide RNAs did not cut either allele of the target gene.

The sequence of a promoter constitutes the most basic mechanism of transcription regulation because: RNA polymerase has differential affinities for different sequences that correlate with the efficiency of transcription. the expression levels of different housekeeping genes are always identical. promoters are always bound by repressors. promoters are always bound by activators.

RNA polymerase has differential affinities for different sequences that correlate with the efficiency of transcription.

Which of the following is NOT a characteristic of the transcriptional ground state in higher eukaryotes? Access to promoters is restricted by the structure of chromatin. Virtually every gene requires activation. RNA polymerase initiates efficient transcription in the absence of repressors. Gene promoters are essentially inactive in the absence of regulatory proteins.

RNA polymerase initiates efficient transcription in the absence of repressors.

Which of the following is TRUE of bacterial translation termination? The ribosome continues to synthesize protein until it reaches the 3′ end of the mRNA. Termination requires the degradation of the ribosome. Termination is signaled by the presence of a stop codon in the mRNA.

Termination is signaled by the presence of a stop codon in the mRNA.

Which of the following BEST describes the translational elongation process? tRNA molecules condense with rRNA molecules. Ribonucleotides are added to amino acids through the synthesis of phosphodiester bonds. The polypeptide chain is lengthened by synthesizing peptide bonds between amino acids. Ribosomal proteins aggregate to form polysomes.

The polypeptide chain is lengthened by synthesizing peptide bonds between amino acids.

Why is green fluorescent protein (GFP) very useful in visualizing fusion proteins in eukaryotes? It is derived from fireflies, which are easy to cultivate in the lab. The GFP protein recognizes and binds to fusion proteins, allowing the location of the fusion protein to be determined. The presence of just a few molecules of GFP fusion proteins can be sufficient to create fluorescence. The reaction is only dependent on the presence of GFP and ATP. It is easily cloned and expressed in bacterial cells.

The presence of just a few molecules of GFP fusion proteins can be sufficient to create fluorescence.

Which of the following statements about translation is NOT true? Protein synthesis begins with the N-terminal end. The AUG initiation codon specifies an N-terminal methionine residue. The three steps of elongation are repeated for each codon of the mRNA. The ribosome is degraded after dissociating from the stop codon.

The ribosome is degraded after dissociating from the stop codon.

Why does mismatch repair NOT lead to mutation upon repair of heteroduplex DNA? The strand containing the misincorporated base is methylated. Actually, mismatch repair does lead to mutation about 50% of the time. The strand containing the misincorporated base is not methylated. The incorrect base is recognized because it is methylated. The strand containing the misincorporated base is phosphorylated.

The strand containing the misincorporated base is not methylated.

What is the source of the energy that both causes and repairs pyrimidine dimers? GTP ATP The sun cAMP Sugar metabolism

The sun

Which of the following is NOT true of small insertions and deletions? They do not cause frameshifts in the amino acid sequence if occurring in multiples of three. They are caused by aberrant recombination or by template slippage during replication. They are collectively called indels. They can result in the formation of fusion genes. If only one or two bases are involved, a frameshift will occur in the amino acid sequence.

They can result in the formation of fusion genes.

Which of the following is NOT true of histone tails? They protrude between the two DNA strands that supercoil around the nucleosome. They are recognized by acetylases and methylases. They have enzymatic properties that can covalently modify DNA. They experience changes in net charge, shape, and other properties of histones in response to modifications. They are the target of numerous chemical modifications.

They have enzymatic properties that can covalently modify DNA.

A mismatch becomes a mutation only when it is incorporated into a replicated, base-paired DNA molecule. True False

True

Which combination reflects the factors binding to genes that are transcribed at activated levels in PK? activator but no repressor neither repressor, nor activator (basal) repressor AND activator (combination) repressor but no activator (repressed)

activator but no repressor

Which of the following is the result of external mutagens? addition of bulky adducts to the DNA replication errors recombination errors template slippage during replication depurination

addition of bulky adducts to the DNA

Which of the following is NOT a function of histone H1? stabilizing nucleosomes enhancing the repression of transcription by nucleosomes promoting higher order chromosome structure All of these options are functions of histone H1. binding to regions undergoing active RNA synthesis

binding to regions undergoing active RNA synthesis

In which ribosome site(s) is an amino acid bound to its corresponding tRNA? E both P and A both E and P P A

both P and A

restriction enzymes cut in... the parental strand of DNA only the coding strand of DNA only both strands of DNA

both strands of DNA

How can a fusion protein be formed? by using oligonucleotide-directed mutagenesis to introduce mutations that cause the expressed protein to fuse to other proteins by the recombination of two proteins in a bacterial cell to form a new hybrid protein by ligating together the sequences of two different genes, creating a new hybrid gene. When expressed, the new gene product is a fusion of the two gene products. by site-directed mutagenesis, where a fragment is replaced with a synthetic sequence containing the altered DNA sequence by removing a portion of the gene, forming a shorter gene and therefore a shorter protein

by ligating together the sequences of two different genes, creating a new hybrid gene. When expressed, the new gene product is a fusion of the two gene products.

Eukaryotic proteins do NOT require a targeting signal if they are destined to function in the: nucleus. lysosome. plasma membrane. cytoplasm.

cytoplasm.

In our current model of EK gene activation, what is the expected order of events? a. histone acetylation and chromatin remodeller recruitment b. chromatin decompaction c. RNA polymerase binding and transcription d. activator binding and histone acetyl transferase (HAT) recruitment

d,a,b,c

Which of the following processes does NOT contribute to the formation of a biologically active form of a protein? posttranslational modification of amino acids degradation of mRNA removal of one or more amino acid residues formation of intrachain or interchain disulfide bonds

degradation of mRNA

Which of the following is NOT an essential component of the eukaryotic elongation stage of translation? magnesium ion eIF3 GTP aminoacyl-tRNAs

eIF3

The CRISPR/Cas9 system requires all of the following enzymatic activities except: ligase. endonuclease. polymerase. exonuclease. All of the above are required.

exonuclease.

genes in polycistronic RNAs are translated as one protein true false

false

The products of the hydrolysis of lactose by β-galactosidase are: galactose and glucose. galactose and allolactose. glucose and allolactose. glucose and ribose.

galactose and glucose.

Histone deacetylation favors: gene activation. gene inactivation.

gene inactivation.

Histone methylation favors: gene activation. gene inactivation.

gene inactivation.

A recombinant DNA was constructed by inserting the DNA of interest into the AmpR gene of a pBR322 vector. The vector also contains a TetR gene that is not interrupted. After introducing the recombinant DNA into bacterial cells, the resulting transformants were tested on a variety of media. Which of the following results would be expected? growth on both ampicillin containing media and tetracycline containing media no growth on either ampicillin or tetracycline containing media growth on tetracycline but not ampicillin containing media growth only on media containing both antibiotics growth on ampicillin but not tetracycline containing media

growth on tetracycline but not ampicillin containing media

The CRISPR/Cas9 system can be considered a bacterial "adaptive immune system" because: it initiates the production of antibodies specific to the infectious agent. it prevents phages from injecting their nucleic acids into bacteria. it is able to predict which phage will infect a bacterium in the future. it requires short palindromic regions to function. it stores molecular elements of infectious agents to use to fight off future infection by those agents.

it stores molecular elements of infectious agents to use to fight off future infection by those agents.

A student clones a DNA insert into the SalI site of pBR322. Select all answers that describe the media on which she could expect growth of E. coli containing the recombinant plasmid. http://www.macmillanhighered.com/brainhoney/resource/6716/SitebuilderUploads/cox2e/lor/test_bank/Chapter%207/resources/chapter_7/q7-1.jpg nutrient agar with ampicillin nutrient agar with tetracyline nutrient agar with ampicillin and tetracycline nutrient agar with streptomycin nutrient agar with no antibiotics

nutrient agar with ampicillin, nutrient agar with no antibiotics

A plasmid vector typically has all of the following features EXCEPT: selectable marker. a size range from 4-15 kbp. origin of replication. par genes. unique restriction sites.

par genes.

Which type of bond is formed, and where, in the process of translation? covalent bonds between the sugar-phosphate groups of the DNA molecule peptide bonds between the amino acids to produce the polypeptide chain hydrogen bonds between the nucleotide base pairs of the mRNA molecule and the amino acids ionic bonds between the ribosome and the incoming mRNA molecule van der Waals interactions between the mRNA and the aqueous solution of the cell cytoplasm

peptide bonds between the amino acids to produce the polypeptide chain

Which molecular biology tools will you need to create a plasmid containing a gene of interest? plasmid, restriction enzyme, DNA polymerase, DNA fragment containing the gene plasmid, restriction enzyme, DNA ligase, DNA fragment containing the gene plasmid, restriction enzyme, DNA polymerase, DNA ligase plasmid, DNA polymerase, DNA ligase, DNA fragment containing the gene

plasmid, restriction enzyme, DNA ligase, DNA fragment containing the gene

Which of the following is NOT an example of a regulatory DNA site? repressor insulator enhancer operator

repressor

Which of the following is an enzyme used in cloning that breaks covalent bonds? polynucleotide kinase DNA ligase restriction endonuclease DNA polymerase I reverse transcriptase

restriction endonuclease

Restriction enzymes cleave... any amino acid sequence specific amino acid sequences any DNA sequence specific DNA sequences

specific DNA sequences

A polylinker is a: molecule used to ligate DNA fragments together. DNA sequence that allows for selection of cells that contain the vector. synthetic DNA fragment that contains multiple restriction enzyme sites. synthetic DNA fragment inserted into a vector that allows replication of the vector in the host cell. synthetic DNA fragment used in colony hybridization to visualize colonies that contain the DNA of interest.

synthetic DNA fragment that contains multiple restriction enzyme sites.

What makes a strong or weak promoter? the DNA sequence the number of binding sites for activators and repressors the location in the genome

the DNA sequence

Which site on the ribosome is NEVER occupied by a tRNA linked to a nascent polypeptide chain? the A site the P site the E site

the E site

The site in the ribosome that carries the peptide chain is the P site the E site the A site

the P site

How does the MMR (mismatch repair) machinery know which strand to keep and which one to replace during repair? the parental strand is methylated the MMR proteins travel with the DNA replication machinery and therefore know which strand was just synthesized the new strand is methylated it is random

the parental strand is methylated

The cutting sites of restriction enzymes are often... similar to each other between different restriction enzymes different sequences on the two DNA strands complementary to DNA ligase binding sites the same sequence on both DNA strands read in 5' to 3' direction

the same sequence on both DNA strands read in 5' to 3' direction

At which step is gene regulation most often controlled? transcription initiation translation RNA stability protein transport

transcription initiation

The human genome is mostly composed of: introns. long repetitive sequences like centromeres and telomeres. protein-coding genes. active retrotransposons. transposons and retrotransposons that are mostly inactive.

transposons and retrotransposons that are mostly inactive.

ribosomes are ribozymes true false

true

Restriction enzymes: are necessary for joining two DNA fragments together. typically cleave at palindromic sequences 4-8 base pairs long. are found in a wide variety of mammalian cell types. always produce sticky ends. cleave invading bacterial DNA.

typically cleave at palindromic sequences 4-8 base pairs long.

The deamination of cytosine leads to: guanine. adenine. uracil. methylcytosine. thymine.

uracil.