Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL 3321 - cell and molecular bio > post-transcriptional gene control > Flashcards

post-transcriptional gene control Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

list the forms of post transcriptional gene control

A

RNA processing, RNA transport out of the nucleus, RNA degradation, and translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are riboswitches

A

short sequences of RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

where are riboswitches located on the RNA strand

A

near the 5’ end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

which organism are riboswitches common in

A

bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what do riboswitches do for gene control

A

they regulate the activity of RNA pol via conformational changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

in bacteria, which amino acid are riboswitches used to control the biosynthesis of

A

guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe riboswitches controlling purine synthesis

A

one conformation aids in elongation

another conformation, when guanine is bound to it, RN pol doesn’t transcribe = no purine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is splicing

A

a process in which the introns are removed from pre-mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what carries out splicing

A

5 small nuclear RNAs (snRNAs) + associated proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the 5 snRNAs that carry out splicing

A

U1, U2, U4, U5, U6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what do each snRNA and its associated proteins form

A

a small nuclear ribonucleoprotein particle (snRNP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is an snRNP

A

a snRNA + its associated proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a spliceosome

A

the structure formed when all the snRNPs and splicing factors are assembled on the pre-mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the 3 consensus sequences around splice sites in pre-mRNAs

A

5’ GU, 3’ AG, and the A branch point in the middle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the GU-AG rule

A

the 5’ GU and the 3’ AG are always there

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does the mRNA form when the introns are removed

A

a lariat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what do SR proteins do

A

they bind to exons and help define splice sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what snRNAs do SR proteins recruit to splice sites

A

U1 and U2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what do hnRNPs do

A

they bond to introns to help the spliceosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

list all the proteins involved in splicing

A

snRNP (snRNA + proteins), SR proteins, hnRNPs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

T or F: an RNA transcript can be spliced in more than one way

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is it called when a transcript can be spliced in more than one way

A

alternative splicing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the purpose of alternative splicing

A

allows one gene to produce several related proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

how many genes are in the human genome

A

~21,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how many proteins can humans make due to alternative splicing

A

more than 70,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

T or F: for most human genes, alternative splicing occurs

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what are the two types of RNA splicing regulation

A

positive control

negative control

28
Q

describe positive control of RNA splicing regulation

A

an activator protein is required in order for an intron to be recognized

29
Q

describe negative control of RNA splicing regulation

A

a repressor protein can bind to the mRNA and block access of the spliceosome

30
Q

what is the poly(A) site

A

it’s where the RNA transcript is cleaved and where the adenines are added to form the 3’ tail

31
Q

where is the poly(A) site

A

at the end of the coding sequence for a gene

32
Q

what is the first step of pre-mRNA processing

A

after transcription, the 5’ cap is added

33
Q

after the 5’ cap is added to the transcript, what happens

A

cleavage at the poly(A) site occurs

34
Q

what enzyme cleaves at the poly(A) site of the pre-mRNA transcript

A

an endonuclease

35
Q

after cleavage at the poly(A) site, what occurs

A

polyadenylation occurs at the 3’ site

36
Q

how many adenines are added in polyadenylation

A

~250

37
Q

what enzyme is responsible for polyadenylation

A

Poly(A) polymerase (PAP)

38
Q

what occurs after polyadenylation

A

RNA splicing, leaving us with a mature mRNA

39
Q

describe a mature mRNA

A

has a 5’ cap, has been cleaved at the poly(A) site, has a 3’ poly A tail, and has introns removed

40
Q

what is the recognition sequence for polyadenylation

A

AAUAAA

41
Q

what is AAUAAA

A

the polyadenylation recognition sequence

42
Q

what is another name for AAUAAA

A

the Poly(A) signal

43
Q

where is the poly(A) signal located

A

15-30bp upstream from the poly(A) site

44
Q

other than the poly(A) signal, what is an important region during polyadenylation

A

the GU-rich or U-rich region

45
Q

where is the GU-rich/U-rich region located

A

~20bp downstream from the cleavage site

46
Q

what thing recognized the poly(A) signal (AAUAAA)

A

CPSF

47
Q

full name of CPSF?

A

cleavage and polyadenylation specificity factor

48
Q

what thing recognizes the GU-rich/U-rich signal

A

CstF

49
Q

full name of CstF?

A

cleavage stimulation factor

50
Q

where are CPSF and CstF found

A

on the CTD region of RNA pol

51
Q

starting at CPSF and CstF, describe the mechanism of polyadenylation

A

CPSF and CstF transfer from CTD to mRNA recognition sequences, and then additional factors (including PAP) bind. PAP binding = cleavage at poly(A) site, PAP adds A’s

52
Q

after all the As are added to the transcript, what type of protein binds

A

poly(A) binding proteins (PABPs)

53
Q

role of poly(A) binding proteins?

A

helps with export of the mRNA out of the nucleus and it protects mRNA from being degraded by exonucleases

54
Q

T or F: there may be alternative poly(A) sites

A

true

55
Q

what is the result of having alternative poly(A) sites

A

results in the productions of proteins that vary at their C terminus

56
Q

what percentage of human genes coding for proteins have more than 1 poly(A) site

A

~50%

57
Q

what factors influence which poly(A) site is used when there are multiple ones

A

the type of cell, concentration of CPSFs and CstFs, the sequence of the polyA signal (high or low affinity), presence of RNA binding proteins that either inhibit/enhance the binding of needed factors for polyadenylation

58
Q

what is the concentration of CstF in a resting B cell + what type of transcript is produced + where will the protein be located

A

low CstF, so it only recognizes a strong affinity site = longer transcript produced. This codes for hydrophobic amino acids = membrane bound protein made

59
Q

what is the concentration of CstF in an active B cell + what type of transcript is produced + where will the protein be located

A

CstF = high so it recognizes the weak affinity site = shorter mRNA produced = no hydrophobic region = protein is secreted and not membrane bound

60
Q

what are the two types of RNA editing

A

A to I
C to U

61
Q

when will RNA editing affect the protein produced

A

only when the edits lead to changes within coding regions

62
Q

why does RNA editing occur

A

originated as a defense against viruses

63
Q

what two things can RNA editing lead to

A

a change in the amino acid sequence of the protein or a truncated protein

64
Q

what enzyme carried out A to I edits

A

ADARs

65
Q

describe what occurs that leads to A to I editing

A

complimentary bases in an intron pair up, making a double stranded RNA. This attracts ADAR which makes the edit

66
Q

what is the C to U edit important for

A

production of two variants of apolipoprotein

67
Q

describe the C to U edit using the apolipoprotein as an example

A

in liver, no editing occurs because the enzymes for editing aren’t expressed = full length protein produced

in the intestines, the edit happens = stop codon made = truncated protein produced

BIOL 3321 - cell and molecular bio (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions