exam 2 (hw questions)

Question 1

Bacterial DNA associates with various proteins to form a structure called the:

Answer 1

nucleoid

Question 2

Which of the following chromatin features would you expect to find in a region of heterochromatin?

• H3K9me3
• H3K27ac
• Low levels of DNA methylation
• Low nucleosome occupancy

Answer 2

H3K9me3

Question 3

RNAPs catalyze the formation of what type of bond?

Answer 3

phosphodiester

Question 4

Which of the following is NOT a mechanism by which ATP-dependent chromatin remodelers can expose specific DNA sequences wrapped into nucleosomes?

• Sliding of nucleosomes
• Targeting of histones for destruction
• Unwrapping of nucleosomal DNA
• Eviction of nucleosomes

Answer 4

targeting of histones for destruction

Question 5

what regions of a mammalian genome would you expect to have a high level of DNA methylation?

Answer 5

transposable elements

Question 6

Histones are uniquely able to form strong interactions with DNA due to what feature?

Answer 6

Their unusually high basic amino acid content

Question 7

Which subunit of bacterial RNAP targets it to specific sets of promoters?

Answer 7

sigma

Question 8

Polycomb silencing and Trithorax activation are chromatin regulatory processes that primarily act on what histone residue?

Answer 8

H3K27

Question 9

Which of the following histones is not part of the core nucleosome octamer?

• H4
• H1
• H2A
• H3

Answer 9

H1

Question 10

Bacterial RNAP is capable of denaturing DNA at promoters. It can thus be considered what type of enzyme?

Answer 10

helicase

Question 11

Which component of the lac operon system encodes the lac repressor?

Answer 11

lacl

Question 12

which eukaryotic RNAPs transcribes rRNA?

Answer 12

RNAP1

Question 13

lacOc mutations only cause constitutive expression of lac mRNA when they are on the same strand as a normal copy of lacZ. this means that they are is of what formation?

Answer 13

cis-domainant

Question 14

Most eukaryotic promoters do not have a TATA box and so rely on what general transcription factor to begin PIC assembly?

Answer 14

TFIID

Question 15

Which module of Mediator is responsible for contacting RNAPII bound to promoters?

Answer 15

head

Question 16

The attenuator hairpin in the trp leader mRNA is formed by the interaction of what two leader segments?

Answer 16

3 and 4

Question 17

Which of the following elements would you not expect to find in a eukaryotic core promoter?

• Inr
• -10 box
• TATA box
• BRE

Answer 17

-10 box

Question 18

When glucose is added to a lactose-containing bacterial culture medium, the transcription of lac mRNA is silenced via what mechanism?

Answer 18

catabolite repression

Question 19

Eukaryotic TFIIH serves what function in the context of the PIC?

Answer 19

promoter DNA melting

Question 20

The trp operon encodes five enzymes and is shut off in response to high levels of tryptophan in the cells’ growth medium. These enzymes therefore fall into what category?

Answer 20

repressible

Question 21

what eukaryotic transcription-related proteins is equivalent to bacterial GreA/GreB in the rescue of stalled RNAPs?

Answer 21

TFIIS

Question 22

RNA editing can recode an “A” base in mRNA to what nonstandard base?

Answer 22

Inosine

Question 23

Which of the following eukaryotic transcription-related proteins is NOT involved in the regulation of RNAPII pausing?

• TFIID
• NELF
• DSIF
• p-TEFb

Answer 23

TFIID

Question 24

What feature of eukaryotic mRNAs can be used to purify them from bulk cellular RNA?

Answer 24

Poly(A) tail

Question 25

Which histone modifications or variants would you expect to find primarily in the bodies of active genes?

Answer 25

H3K36me3

Question 26

RNAPII transcription termination is coupled to what stage of RNA processing?

Answer 26

Cleavage and polyadenylation

Question 27

Transcriptional activators bound to enhancers are contacted by what module of the Mediator complex?

Answer 27

tail

Question 28

Which of the following is NOT a function of EUKARYOTIC mRNA polyadenylation? - Nuclear export of mRNAs - Destabilization of mRNAs -Recruitment of translation-related proteins to mRNAs - Stabilization of mRNAs

Answer 28

-Destabilization of mRNAs

Question 29

which organism has the longest intron

Answer 29

human

Question 30

Which of the following biological phenomena we discussed was not discovered in a virus? - Split genes - Gene regulation by enhancers - DNA methylation - All of these were first described in viruses.

Answer 30

DNA methylation

Question 31

Eukaryotic mRNAs can be isolated from total cellular RNA due to the presence of what sequence feature?

Answer 31

poly(A)-tail

Question 32

Circular bacterial chromosomes interact with proteins to form a condensed structure known as the:

Answer 32

nucleoid

Question 33

Which module of the Mediator complex is responsible for interaction with the promoter-bound general transcription machinery?

Answer 33

head

Question 34

Which of the following is a false statement regarding mRNA capping? - The cap is placed at the 5’ end of the pre-mRNA - The cap enhances degradation of mRNAs by exonucleases - Most mRNAs are capped - Capping occurs co-transcriptionally

Answer 34

The cap enhances degradation of mRNAs by exonucleases

Question 35

The complete, catalytically competent form of an enzyme is referred to as a(n):

Answer 35

holoenzyme

Question 36

The eviction of HP1 and TFIID from chromosomes during mitosis is mediated by the interplay between what two types of histone modification?

Answer 36

methylation and phosphorylation

Question 37

What is the function of lacO within the lacoperon?

Answer 37

it serves as bonding site for the lac repressor

Question 38

Which of the following chromatin features would you notexpect to find at a heterochromaticregion? - High levels of histone acetylation - high levels of DNA methylation - H3K9me3 - sensely packed nucleosomes

Answer 38

High levels of histone acetylation

Question 39

RNA editing recodes A to which nonstandard base?

Answer 39

inosine

Question 40

While bacterial RNAP contains the helicase activity necessary to melt promoter DNA, eukaryotic RNAPII requires some help. What general transcription factor performs this function?

Answer 40

TFIIH

Question 41

hnRNA was an early term for what type of RNA

Answer 41

unprocessed mRNA

Question 42

RNAP accumulates enough energy to transition from abortive initiation to productive elongation through what mechanism?

Answer 42

scrunching

Question 43

What is the correct order of the RNA processing events listed below?

Answer 43

capping, cleavage, polyadenylation

Question 44

what amino acid can not be phosphorylated by a kinase

Answer 44

cysteine

Question 45

Which of the following elements is not involved in bacterial intrinsic transcription termination? - stem loop - rut site - U-rich region - all of these participate

Answer 45

rut site

Question 46

Operons generate single mRNAs containing multiple protein-coding sequences. What is the generally accepted term for this type of mRNA?

Answer 46

polycistronic

Question 47

telomeres are bound by what specialized eukaryotic protein complex

Answer 47

shelterin

Question 48

the eukaryotic Xrn2 protein is involved in what step of mRNA processing?

Answer 48

termination

Question 49

The enzymes encoded by the lac operon are turned on in response to a specific stimulus –the addition of lactose to the bacterial culture medium. These enzymes are thus of what class?

Answer 49

inducible

Question 50

Bridging between eukaryotic enhancers and promoters is often achieved by what protein complex?

Answer 50

mediator