New: RNA synthesis, regulation, and processing

Question 1

transcription of genes is

Answer 1

regulated

Question 2

expression of housekeeping genes is

Answer 2

constitutive

Question 3

housekeeping genes usually have strong promoter and are efficiently and continuously

Answer 3

transcribed

Question 4

housekeeping genes whose products are required at low levels have

Answer 4

weak promoter and are infrequently transcribed

Question 5

________ ____ are expressed at different levels under different conditions

Answer 5

regulated genes

Question 6

HAT

Answer 6

modify histones and open up DNA so other things can bind

Question 7

gene expression is also regulated by ______ such as estradiol

Answer 7

hormones

Question 8

the estrogen receptor is part of a larger class of regulatory proteins called ______ _____ ______

Answer 8

nuclear hormone receptors

Question 9

nuclear hormone receptors are all activated by binding of small molecules or ligands and bind to specific regions of the DNA called

Answer 9

response elements

Question 10

nuclear hormone receptors have two conserved domains which are

Answer 10

1. the DNA binding domain

2. ligand binding domain

Question 11

has zinc finger domains that confer specific DNA binding

Answer 11

DNA binding domain

Question 12

ligand binding to the ligand binding domain causes a

Answer 12

structural change that enables the receptor to recruit other proteins to regulate transcription

Question 13

coactivators and corepressors are recruited by

Answer 13

nuclear hormone receptors

Question 14

proteins that bind the receptor after ligand binding are called

Answer 14

coactivators

Question 15

ligand binding leads to structural rearrangements in the receptor that promotes

Answer 15

recruitment of additional proteins

Question 16

_______ proteins bind to nuclear hormone receptors when ligand is absent to assist in repression of transcription

Answer 16

corepressor

Question 17

ligands that activate a nuclear hormone receptor

Answer 17

agonists

Question 18

ligands that inhibit the receptor

Answer 18

antagonists

Question 19

some cancers require the estradiol-receptor complex, and growth of these cancers can be slowed by administering receptor antagonists such as

Answer 19

tamoxifen and raloxifene

Question 20

good and bad effects of tamoxifen

Answer 20

good: decrease cancer and cholesterol; increase bone strength
bad: increase blood clots and uterine cancer

Question 21

histone acetylation results in chromatin

Answer 21

remodeling

Question 22

*how do coactivators stimulate transcription?

Answer 22

loosening the interactionbtwn histones and DNA, so the DNA is more accessible to transcription machinery

Question 23

acetylation reduces the affinity of histones for

Answer 23

DNA

Question 24

histone acetyllysine residues are interaction sites for many proteins which regulate ________, including factors which bind the TATA-box

Answer 24

transcription

Question 25

acetyllysine residues also bind and recruit

Answer 25

chromatin remodeling proteins

Question 26

histone acetylation is carried out by

Answer 26

histone acetyltransferases (HATS)

Question 27

lysine residues can be

Answer 27

acetylated

Question 28

histone acetylation ________ net positive charge - weakens interactions with other nucleosomes and proteins, loosens higher order structure

Answer 28

decreases

Question 29

HATS directed to sites where chromatin must unravel to

Answer 29

transcribe a gene

Question 30

histone deacetylases (HDCs)

Answer 30

remove acetyl groups - allow for re-compacting of DNA

Question 31

in RNA processing of eukaryotes, large precursor RNA (45S) is processed to

Answer 31

18s, 28s, and 5.8s rRNAs...which are components of the ribosome

Question 32

before cleavage, some bases and riboses are modified in a process catalyzed by RNA-protein complexes called

Answer 32

small nucleolar ribonucleoproteins (snoRNP)

Question 33

tRNA endonucleases remove nucleotides from the

Answer 33

5' end

Question 34

tRNA nucleotidyl transferase* adds _____ to the ____ end

Answer 34

CCA; 3'

Question 35

in prokaryotes the primary mRNA transcript is translated

Answer 35

directly

Question 36

in eukaryotes transcription occurs in the

Answer 36

nucleus

Question 37

in eukaryotes translation occurs in the

Answer 37

cytoplasm

Question 38

splicing

Answer 38

in some mRNA pieces are removed from the middle and the ends joined

Question 39

eukaryotic mRNA molecules have modified ends: eukaryotic mRNA precursors undergo modification to

Answer 39

increase their stability* and make them better substrates for translation

Question 40

eukaryotic mRNA molecules have modified ends: ends are modified to they are no longer susceptible to

Answer 40

exonuclease degradation*

Question 41

eukaryotic mRNA molecules have modified ends: the 5' ends are modified (capped) before the mRNA precursors are completely

Answer 41

synthesized

Question 42

addition of ___ required for splicing and other processing events

Answer 42

CAP

Question 43

cap site is where _______ bind

Answer 43

ribosomes

Question 44

cap is added by

Answer 44

gyanylyl transferase

Question 45

poly A tails at the 3' ends of ____ precursors

Answer 45

mRNA

Question 46

eukaryotic mRNA precursors are also modified at their

Answer 46

3' ends

Question 47

a poly A polymerase adds up to ____ ____ residues to the 3' end of the mRNA precursor

Answer 47

250 adenylate

Question 48

poly a tail is progressively shortened by

Answer 48

3' exonucleases

Question 49

the poly A tail increases the time before nucleases reach

Answer 49

the coding region

Question 50

sequences at the ends of introns specify

Answer 50

splice sites in mRNA precucrsors

Question 51

most genes in eukaryotes consist of

Answer 51

exons and introns

Question 52

introns

Answer 52

internal sequences that are removed from the primary RNA transcript.

Question 53

exons

Answer 53

sequences that are present in the primary transcript and the mature mRNA

Question 54

splice sites

Answer 54

junctions of the introns and exons where mRNA precursor is cut and joined

Question 55

exons are joined by

Answer 55

splicing

Question 56

small nuclear RNAs in splicosomes catalyze

Answer 56

splicing of mRNA precursors

Question 57

defects in ______ may cause up to 15% of all genetic diseases

Answer 57

splicing

Question 58

introns allow formation of alternative forms of a protein called

Answer 58

splice variants

Question 59

alternative splicing is a powerful mechanism for expanding

Answer 59

protein diversity

Question 60

in alternative splicing, a pre-mRNA can be splices in different patterns, generating proteins with

Answer 60

different funcitons

Question 61

transcription and processing of mRNA are

Answer 61

coupled

Question 62

transcription and splicing of mRNA are coordinated by the

Answer 62

carboxyl-terminal domain (CTD) or RNA pol 2

Question 63

functions of the CTD include:

Answer 63

1. recruit enzymes to synthesize the 5' cap 2. recruit components of the splicing complex 3. recruit an endonuclease that cleaves the pre-mRNA to expose the site for poly A additio