Exam 2 Review

Question 1

when is the lac operon optimally expressed

Answer 1

in presence of lactose and absence of glucose

Question 2

how many different secondary structures(hairpins) may be formed by the Trp leader mRNA

Answer 2

3

Question 3

what regulatory sequence may be located tens of thousands of nucleotides away from the genes they regulate

Answer 3

enhancers
(any trans regulators)

Question 4

what is the role of DNA methylation in eukaryotes

Answer 4

aid in silencing transcription

Question 5

increased acetylation of histones is typically associated with what

Answer 5

gene activation and euchromatin formation

Question 6

which enzyme acts as template for telomere repeat DNA sequence

Answer 6

telomerase

Question 7

the process by which pneumococcus transfers DNA between RII and heat killed SIII is known as what

Answer 7

transformation

Question 8

which direction of DNA will be the lagging strand

Answer 8

side where point of origin moves towards 3’ end

Question 9

what is one difference between DNA replication in bacteria vs eukaryotes

Answer 9

eukaryotic chromosomes have many origins of replication while bacteria only have one

Question 10

if single stranded binding protein is not present during DNA replication what would you expect to see

Answer 10

SSB prevents reannealing, so strands would quickly reanneal and DNA replication could not proceed

Question 11

why are leading strand primers removed rather than joined like okazaki fragments

Answer 11

they contain nucleotides with 2’OH groups, and are targeted for excision by DNA polymerase

Question 12

a plant cell exhibits in transcription of tRNA genes, which polymerase is mutated

Answer 12

RNA plymerase III

Question 13

what region of gene would need to be mutated to prevent access of RNA polymerase to the gene

Answer 13

promoter sequence

Question 14

why does rho dependent transcriptional termination in bacteria require the rho protein

Answer 14

RNA polymerase stalls on termination stem-loop and rho is needed to displace it

Question 15

what defines end of eukaryotic gene

Answer 15

presence of polyadenylation signal sequence leads to cleavage of pre-mRNA

Question 16

what is the purpose of alternative splicing in eukaryotic cells

Answer 16

produce multiple polypeptide sequences from a single primary transcript

Question 17

role of promoter region

Answer 17

recruit transcription factors that form initiation complex

Question 18

what is the shine-dalgarno sequence in bacteria

Answer 18

purine-rich sequence found in 5’ UTR of mRNA

Question 19

how does eukaryotic ribosomal small subunit recognize start codon on mRNA

Answer 19

binds met-tRNA to first AUG codon after kozak sequence

Question 20

what would you expect to find bound to stop codon at A site

Answer 20

translation release factor

Question 21

how would a single base insertion into second codon of sequence affect AA sequence

Answer 21

AA sequence would be changed

Question 22

difference between NER and BER

Answer 22

NER detects ribosomes in double helix, BER removes damaged bases

Question 23

which class of point mutation almost always results in mutant phenotype

Answer 23

frameshift

Question 24

2 mutagens classified as base analogs

Answer 24

5-bromouracil
2-aminopurine

Question 25

2 forms of double stranded break repair

Answer 25

NHEJ SDSA

Question 26

how is DNA replication in both prokaryotes and eukaryotes described

Answer 26

bidirectional and semiconservative

Question 27

which protein is responsible for initiation of oriC in E. coli

Answer 27

DnaA

Question 28

sequence of steps in PCR

Answer 28

denaturation, primer annealing, primer extension

Question 29

where does sigma subunit of bacterial RNA pol bind

Answer 29

bacterial gene's promoter

Question 30

what is a characteristic of short tandem repeats in genetic analysis

Answer 30

STRs segregate independently

Question 31

A mutation of the O region of the lac operon would most likely result in what?

Answer 31

constitutive expression of lac operon, whether or not lactose was present, as the repressor cannot bind

Question 32

in griffins experiment did mice die

Answer 32

live IIIS and live IIR with dead IIIS

Question 33

which protein removes RNA primer from nascent DNA in E. coli

Answer 33

DNA polymerase I

Question 34

properties of holoenzyme but not core enzyme

Answer 34

promoter recognition and binding

Question 35

property of core enzyme but not holoenzyme

Answer 35

5' to 3' synthesis

Question 36

necessary component of intrinsic but not rho dependent terminators in E. coli

Answer 36

string of U's in RNA

Question 37

during transcription in E. coli when does sigma subunit fall off

Answer 37

after first 8-10 RNA nucleotides

Question 38

role of general transcription factors

Answer 38

GFT binds to core promoter and allow transcriptional initiation

Question 39

function of shine dalgerno sequence

Answer 39

specification of authentic start codon in bacterial RNA

Question 40

what will never be found in A-site of ribosome

Answer 40

initiator tRNA(that will be in P-site)

Question 41

in bacterial translation initiation, the mRNA...

Answer 41

is oriented on small subunit by shine dalgarno sequence through base pairing with an rRNA

Question 42

last component incorporated in process of translation initiation

Answer 42

large ribosomal subunit

Question 43

what complex(es) binds to open A site in process of translational elongation

Answer 43

charged tRNA elongation factor GTP

Question 44

what class of mutation generally creates decreased amount of gene product

Answer 44

promoter mutations

Question 45

strand slippage during DNA replication generally results in what type of mutation?

Answer 45

expansion of trinucleotide repeat sequence

Question 46

spontaneous nucleotide changes

Answer 46

depurination and deamination

Question 47

alkylating agents generally result in what type of mutations?

Answer 47

base substitutions

Question 48

what repair mechanism is used most to repair thymine dimers

Answer 48

photoactivation repair

Question 49

presence of what combination of molecules could prevent transcription of a repressible operon

Answer 49

repressor and corepressor

Question 50

binding of which complex increases ability of RNA polymerase to transcribe the lac operon

Answer 50

cap-cAMP operon

Question 51

what complex transports regulatory RNAs to RNAs targeted for degradation or inhibition of translation

Answer 51

RISC

Question 52

what is most efficient at changing gene expression through RNA interference

Answer 52

DS RNA that includes gene sequence you want to silence

Question 53

what is primarily responsible for genomic imprinting

Answer 53

methylation of cytosine in DNA