spring 26 biol 242 exam two

The Avery-MacLeod-McCarty experiment demonstrated that....

The ability of heat-treated IIIS bacteria lysate to transform non-virulent bacteria was sensitive to DNase..

According to Chargaff's rule, a species with 20% adenine in its genome will have ______ of guanine in its DNA

30%

Chromatin organized as naked DNA is known as..

2 nm fiber.

The phenomena of hybrid dysgenesis is caused by...

Drosophila males with P elements mated with females without P element

Chromatin organized into solenoids is known as

30 nm fiber.

In E. coli, insertion sequences insert themselves by generating staggered cuts in the target sites, resulting in

The formation of flanking direct repeats.

During E. coli cell division, one round of DNA replication is initiated by?

The binding of dnaA to oriC.

Which of the following activity can remove incorrectly inserted nucleotides during E. coli DNA replication?

The 3'-5' exonuclease activity of DNA polymerase III.

During DNA replication, which one of the following enzymes has the ability to synthesize DNA using RNA template?

Telomerase.

During DNA replication, which one of the following enzymes has the ability to synthesize RNA using DNA template?

Primase.

Regarding the splicing of autocatalytic introns, which of the following statements is correct?

The splicing of group I requires a exogenous guanosine as a cofactor.

In spliceosome-mediated splicing, the 5' splice donor site is cleaved by the formation of lariat, which is generated by

A 5'-2' linkage.

The addition of 5'-methylguanosine cap is mediated by

A 5'-5' linkage.

Regarding histones, which of the following statements is correct?

They complex with 147bps of DNA to form nucleosomes.

Regardring the Hershey-Chase experiment, which of the following statements is accurate...

Bacteria infected with 32P-labeled phages contained radioactivity.

When a λ phage with a loss-of-function mutation in CII infects bacteria, which of the following events is likely to occur?

The mutant phage will enter lytic cycle.

Regarding cro in λ operon, which of the following statements is correct?

Cro binds to DNA with a helix-turn-helix motif.

A deletion of the 6 U's in trpL will

Have transcription into the trpE region, regardless of the tryptophan level in the cell.

A deletion of region 2 will

Have transcription terminated after trpL regardless of the tryptophan level in the cell.

Which of the following statements best describes the regulation of OmpF expression by micF?

micF is an RNA, and binds to OmpF mRNA.

paracentric inversion

inversion that does not include the centromere

pericentric inversion

inversion that includes the centromere

The phenomena of semi-sterility is caused by

Adjacent segregation of reciprocal translocated chromosomes

Bill and Betty have had two children with Down Syndrome, Bill's brother has Down syndrome and his sister has two children with Down syndrome. On the basis of these observations, which of the following statements in most likely correct?

Billy carries a Robertsonian translocation of chromosome 21 with chromosome 14.

Erwin Chargaff demonstrated that

In the DNA of any given species, the content of A is equal to T, and the content of G is equal to C.

In prokaryotic transcription, the Pribnow (-10) box is recognized by

σ subunit of RNA polymerase.

During DNA replication, which one of the following enzymes has the ability to synthesize RNA using DNA template?

Primase

The Drosophila P element utilizes non-replicative transposition. Based on this, which of the following statements is correct?

the P element does not form cointegrant during transposition.

Which of the following Drosophila crosses will generate sterile progeny with numerous chromosomal aberrations?

Males with P elements mated with females without P element

Chromatin organized into loops is known as

300 nm fibers

Histones

small, positively-charged, and highly conserved proteins found in all eukaryotes

Regarding the splicing of eukaryotic mRNA, which of the following statements is correct?

This process requires snoRNP

The 16S rRNA binds to

the Shine-Dalgarno sequence

The Drosophila sex-lethal (sxl) gene regulates its own expression. Which of the following statement best describes this regulation?

Sxl influences the splicing of sxl mRNA.

An insertion of three nucleotides after the AUG start will

Have no effect on trp attenuation.

A deletion of region 4 will

Allow the transcription to proceed into trp structural genes even when tryptophan level is high.

A deletion of region 2 will

Cause the transcription to end after trpL even when tryptophan level is low.

Which of the following modifications is likely to decrease gene expression in eukaryotes?

Methylation of cytosines in CG islands near promoters.

Which of the following enzymes is a RNA-dependent DNA polymerase?

telomerase

When a ribosome encounters a stop codon, the codon is recognized by?

releasing factor

Regarding tRNA charging, which of the following statements is correct

A charged tRNA has the corresponding amino acid bound to the CCA sequence at the 3' end.

Treating eukaryotic chromatins with low level of DNase before running the reaction on a DNA gel is likely to yield?

A ladder of bands with an interval of ~200 bps.

When a λ phage infects bacteria, the decision to enter lytic or lysogenic cycle is influenced by the level of protease in the host cells. Which of the following proteins is the sensor of the cellular protease level?

CII

When bacteria carrying a λ prophage are exposed to UV light, λ repressor will:

Be cleaved by RecA.

In E. coli DNA replication, which of the following enzymes has 5'-3' exonuclease activity?

DNA polymerase I.

The direct repeats found at both ends of transposons are

Generated by staggered cuts of the target sequences during transposition

The hallmark of replicative transposons is that

They form cointergrants during transposition.

Which of the following events is usually associated with an increase in gene expression in eukaryotes

The methylation of histone tails by histone methyltransferases

A crossover between two direct repeats on the same chromosome will generate

A deletion and a circular DNA

microRNA usually inhibits gene expression by

Inhibiting translation of mRNA.

A crossover between two inverted repeats on the same chromosome will generate

An inversion

A circular DNA of 200 bps with 18 helical turns is likely to contain

2 negative supercoils.

Which of the following factors recognizes yeast autonomous replicating sequences

ORC protein.

Which of the following is a DNA-dependent RNA polymerase (making RNA off DNA template)?

Primase

A virus contains 10% adenine, 24% thymine, 30% guanine, and 36% cytosine. The genetic material in this virus is

single stranded

Within cells, the most abundant RNA class is

rRNA

In Maize, the Ds element cannot mobilize in the absence of Ac element because

the Ds element does not contain a functional transposase.

Which of the following enzymes is an example of topoisomerase

gyrase

DNA wrapped around histone octomers is known as

11 nm fiber

The autonomous replicating sequences are

Recognized by origin recognition complex.

A deletion of region 3 will

Allow the transcription to proceed into trp structural genes even when tryptophan level is high

Aminoacyl-tRNA synthetases are responsible for attaching amino acids to tRNAs. Let's suppose that tryptophanyl-tRNA synthetase was partially defective at attaching tryptophan to tRNA; its activity was only 10% of that found in a normal bacterium. How would that affect attenuation of the trp operon?

ribosomes will stall at the leader and the structural genes will be transcribed

Which of the following chromosomal regions are likely to contain heterochromatic DNA?

Centromeres, Telomeres, and Barr bodies.

Which of the following terms describes the formation of lariat?

A 5'-2' linkage

Which of the following items is responsible for the proofreading activity during E. coli DNA replication?

The 3'-5' exonuclease activity of DNA polymerase III.

A λ phage with defective λ repressor (mutation in CI) will be

Unable to enter lysogenic cycle when infecting bacteria.

the deacetylation of lysine residues in histone tails is thought to

allow DNA binding less tightly to histone proteins

the deletion of shine-dalgarno will

Cause the transcription to end after trpL even when tryptophan level is low.

What mutagens is most likely to cause a T^T dimer?

UV light

What is most likely to cause an insertion?

Intercalating agents

What mutagen is most likely to cause an inversion?

Ionizing radiation

Deamination of cytosines are mostly repaired by?

Base excision repair

What repair system utilizes DNA glycosylase?

Base excision repair

In many eukaryotic organisms, a significant proportion of cytosine bases are naturally methylated to a 5-methylcytosine (we went over an example of this in genomic imprinting). Through evolutionary time, the proportion of AT base pairs in the DNA of these organisms increases. This is likely to occur through:

Deamination

Loss-of-function mutations in dam methylase will increase mutation rate in E. coli because:

The mismatch repair system cannot distinguish the newly synthesized strand

Digestion of E. coli DNA with the restriction enzyme ClaI (which cuts at the sequence ATCGAT) is inhibited when its restriction sequence overlaps with GATC. For instance, ClaI will not cleave the ATCGAT in ATCGATC. This happens because the A's in the GATC sequences are methylated in E. coli. To circumvent this problem, researchers can prepare DNA from a dam- strain, which can then be cut by ClaI. However, after this step, it is advised to re-sequence the cloned DNA before proceeding further. Why do you think this additional sequencing is necessary?

The probability of the cloned DNA containing undesired point mutations is higher

Dideoxy-nucleotides are chain terminators because:

They lack hydroxyl group at the 3' position, which is critical for DNA polymerization

The restriction endonuclease NotI recognizes GCGGCCGC. The average length of DNA fragments generated by NotI digestion is expected to be:

65 kb

Closely related genes are referred to as:

homologs

In genome projects, continuous DNA sequences are known as:

Contigs

Wild-type E. coli cells are grown in a medium containing lactose as the sole carbon source. cDNA made from these cells is labeled RED. The same E. coli cells are grown in a medium containing glucose as the sole carbon source. cDNA from these cells is labeled GREEN. Both sets of cDNA are hybridized to the microarray. What color would you expect the spot representing the lacZ gene to be??

Red

The same experiment is done with a lacI- mutant strain of E. coli. What color would you expect the spot representing lacZ to be?

Yellow

In the microarray from part A, 400 spots are red, and 140 are green. Are more genes turned off or turned on by the switch from lactose to glucose?

Off

The genomic DNA from E. coli is made into a library and subjected to whole-genome sequencing. After the completion of the project, the number of contigs should be

1

The yeast 2-hybrid screen identifies genes based on:

The ability of the gene products to physically interact with the bait fusion

In comparing Drosophila and human genomes, which of the following statements is correct?

The number of identified protein motifs is similar

In generating a cDNA library, total RNA prepared from a tissue is subjected to poly-dT selection (total RNA is passed through a column containing poly-dT oligos). The main objective of this procedure is to

Separate mRNA from tRNA and rRNA

In the Sanger's sequencing method, the chain terminator nucleotides differ from DNA by:

The absence of OH at the 3 position

While analyzing the function of an unknown eukaryotic gene, you noticed that it contains leucine zippers. Based on this information, this gene is likely to:

Code for a protein that forms dimers

Functional transformer (tra) proteins are made in Drosophila females, but not in males. This is accomplished by:

The Sxl-mediated alternative splicing

The Ames test demonstrates that:

Certain chemicals, after processed by liver enzymes, are mutagenic

The human disease xeroderma pigmentosum is caused by disruption of:

Nucleotide excision repair pathway

Which of the following events is most likely to cause frameshift mutations?

Treating cells with intercalating agents

A microarray (gene-chip) experiment is useful for:

Comparing the level of mRNA of different genes between cells at two different states

Which of the following statements best describes the generation of expressed sequence tags (ESTs)?

Sequencing ends of cDNA clones

In Drosophila, mutants generated by engineered P-elements allow the technique of plasmid rescue. The goal of this technique is to:

Recover the genomic DNA flanking the inserted P element

Comparing genomes from various prokaryotic species, which of the following statements is correct?

Prokaryotic genomes contain few repetitive sequences

The genome size of Staphylococcus aureus, a gram-positive bacterium, is 2.88mb (106 bases). Based on the comparison of prokaryotic genomes, the number of genes in Staphylococcus aureus is expected to be:

2800

Comparing gene density, which of the following statements is correct?

Genomes of different prokaryotic species have similar gene densities

Comparing human and C. elegans genomes, which of the following features is similar?

The number of identified protein domains