Exam 3

In the genome, the reading frame of a coding sequence is determined by…

start codon

In the mismatch reapir system, the MutS protein initiates the repair process by directly recognizing…

disortion of the helix

in multiple DNA repair processes, the relevant lesion and stretch of neighboring sequences is removed. This results in a gap in the DNA helix that is then repaired by

Polymerase 1 and ligase

the genome of _____ssRNA viruses can serve directly as mRNA to translate viral proteins

positive sense

DNA polymerase is an essential protein in the microbial cell. You have a friend that tell you he has a strain of E.coli with a point mutation in the gene encoding DNA polymerase. It dies at high temperatures. when you find the amino acid sequence, you expect to find…

a single amino acid difference

two key enzymes of replication that have been exploited in biotechnology are …

DNA-DNA polymerase, ligase

PCR yields multiple copies of the same stretch of DNA sequence (eg. the tet gene). At least some of these copies are liekly to conatin a base substitution because….

DNA-DNA polymerase makes mistakes

which of the following base substituions causes a nonsense mutation

you cannot tell

When replicating a chromosome, DNA polymerase adds to the ______ end of the leading and the _____ end of the lagging strand

3’,3’

RNA viruses evolve rapidly, due to the fact that

RNA RNA polymerase makes alot of errors

in an operone containing genes WXYZ, a nonsense codon in the middle of gene X will

stop translation of gene X and stop transcription of YX

a nick in double stranded DNA is an intermediate in

recombination, reapir, replication, and conjugation

the - ssRNA animal viruses package which in their virion?

RNA RNA polymerase

which of the following must be encoded on a plasmid?

origin of replication

an operon contains 4 genes, trpABCD. Transcription of this operon generates an mRNA with:

1 terminator and 4 translation start sites

many of the unique features if RNA, compared to DNA are due to

2’ hydroxyl group of ribose

which of the following (do)does not participate in transcription?

ribosomes

a base substituion mutation in the coding sequence of a gene can…

alter the function of the gene product, eliminate the funciton of the gene, have no effect on the funciton of the gene produce, result in a truncated protein poduct

mRNA sequence below includes the END.. not the bgeining of the coding sequence of a gene, the last 3 amino acids of this gene product are

Try-ile-arg

what is the minum # of tRNAs a cell needs for the 4 leucine codons: UUG, CUU, CUA, CUG?

3

attenuation is a regulatory mechanism in bacteria that exploites the ___ to regulate gene expression

doupling of transcription and translation

consider that the biosynthetic genes for the amino acid methioine are regulated at the transcriptional level by standard repressors. In this case methioine would be expected to

bind the repressor and cause it to bind to the operator

A friend tell you about a newly identified global regulatory system. In this system a number of genes (LphA, LphV, LphQ, LphF etc)are induced when there is limiting phosphorus in the environment. None of these gene are in an operone. While characterizing this region, you isolate 2 significant mutants and become correctly convinced that the regulon is controlled by a DNA-binding protein.

you isolated a deletion mutation that caused all the genes in the regulon to be expressed even when there is high levels of phosphorus. This mutation deleted the gene for…

the DNA binding protein that controls the regulon

A friend tell you about a newly identified global regulatory system. In this system a number of genes (LphA, LphV, LphQ, LphF etc)are induced when there is limiting phosphorus in the environment. None of these gene are in an operone. While characterizing this region, you isolate 2 significant mutants and become correctly convinced that the regulon is controlled by a DNA-binding protein.

you were also able to isolate a mutation that caused only one gene , LphA, to be expressed even in the presence of high phosphorus. The most likely site of this mutation is

operator of the LphA gene

A friend tell you about a newly identified global regulatory system. In this system a number of genes (LphA, LphV, LphQ, LphF etc)are induced when there is limiting phosphorus in the environment. None of these gene are in an operone. While characterizing this region, you isolate 2 significant mutants and become correctly convinced that the regulon is controlled by a DNA-binding protein.gene

The DNA binding protein that controls this regulon is a

promoter sequence

genes of a global regulon controlled by an alternative sigma factor are all likely to have a similair

promoter sequence

A cowork supplies you with a PCR product of gene that encodes a protein your company wants to overproduce. you are told the DNA has ONLY the coding sequence of the gene. You must be sure the plasmid you choose to ligate this fragment also has an appropriately placed …

promoter and ribosome binding site

DNA from three different sources, each of which carries a trap gene are identified. Each sample of DNA is introduced into a strain of B.subtilis that has a mutation in trpA and thus is Trp- (cannot grow without trp in medium). which of the DNA sources have the potential to generate Trp+ strain?

plasmid with E.coli DNA

restriction enzymes used in molecular biology originate as part of naturally occuring restriction/ modification systems. In the environment, these pairs can be considered a primitive version of an animal

innate immune system

which of the following mutants could no be found by selection

mutant lacking biosynthetic gene for tryptophan

the lac operon encodes genes required to catabolize lactose and is regulated by a classical repressor protein LacI. A mutation in the lacI gene that prevents transcription of the lac operone would have to be a …

point mutation

the addiction system of plasmid distribution was described in lecture. When cells with plasmid using this system divide, both daughter cells get at least one toxin protein and at least one anti-toxin protein. Despite this, any daughter cell that does not get a plasmid dies. this is because

toxin is stable and anti-toxin is not

recombinational repair and HGT by transduction are similair in that they both require

RecA protein

consider the sequence of an mRNA for a single gene. In such mRNA one would find the sequence for the

terminator

if you delete the terminator of a gene encoding a protein, the gene product is most likely to

function normally