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Biochemistry 2065 > Gene Expression: Transcription > Flashcards

Gene Expression: Transcription Flashcards

1
Q

what is the simplified expression of the central dogma of molecular biology?

A

dna makes RNA makes protein

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2
Q

transcription is the making of __ from a __ template

A

RNA; DNA

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3
Q

only ___ (type of RNA) gets translated into protein molecules

A

mRNA

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4
Q

transcription is catalyzed by a large enzyme common to all life forms ____

A

rna polymerase

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5
Q

transcription proceeds through 3 steps

A
  1. initiation
  2. elongation
  3. termination
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6
Q

what happens in initiation of transcription?

A

RNAP binds to region of DNA called a promoter and the DNA in that region opens up so RNAP can begin transcription

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7
Q

what is a promoter?

A

a base sequence upstream of the coding portion of a gene containing recognition sites for RNAP to bind

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8
Q

T/F RNAP requires a primer to initiate polymerization.

A

false

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9
Q

in bacteria, many dna promoters have recognition sites called the -10 and -35 region because ___

A

they are roughly 10 and 35 nucleotides upstream to the start site

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10
Q

the first nucleotide (start site) of a transcribed DNA sequence (gene) is denoted as ___

A

+1

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11
Q

T/F RNAP is a multisubunit complex

A

t

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12
Q

role of alpha subunit

A

assembly of core enzyme, interacts with regulatory factors

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13
Q

role of the beta subunit

A

takes part in all stages of catalysis

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14
Q

role of beta 1 subunit

A

binds to DNA , takes part in catalysis

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15
Q

role of omega (w) subunit

A

restore denatured polymerase to its native form

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16
Q

role of the sigma 70 subunit

A

promoter recognition

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17
Q

the entire subunit complex of the RNAP is called the __

A

holoenzyme

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18
Q

RNAP without the sigma subunit is called the ___

A

core enzyme

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19
Q

the core enzyme contains the ___

A

active site

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20
Q

in bacteria, sigma factors recognize and bind ___, targeting ___ to site

A

promoters; RNAP

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21
Q

core RNAP is capable of carrying out ___, but it cannot ___

A

transcription; recognize and bind promoter DNA

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22
Q

the holoenzyme RNAP is capable of recognizing and binding ____ and when it does, it forms a ___ complex

A

promoter dna; transcription complex

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23
Q

the holoenzyme is targeted to the gene promoter by the _-

A

sigma factor

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24
Q

sigma factors enable recognition of ___

A

promoter sequence

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25
Q

sigma factors also play a primary role in converting ___ into ___ at the promoter (open-complex formation)

A

dsdna; Ssdna

26
Q

T/F most bacteria have multiple sigma factors, all recognizing their own promoter sequence

A

t

27
Q

location of transcription in eukaryotes

A

nucleus

28
Q

T/F DNA leaves the nucleus in eukaryotes

A

false

29
Q

what are the 3 RNA polymerases in eukaryotes and functions?

A
  1. RNAP 1: makes rRNA
  2. RNAP 2: makes mRNA
  3. RNAP 3: makes tRNA
30
Q

alpha–Amanitin is made by ____ and inhibits ___

A

poisonous mushrooms; RNAP 2

31
Q

which has more subunits, eukaryotic RNAP or bacterial?

A

eukaryotic

32
Q

T/F eukaryotic RNAP has a sigma factor

A

f

33
Q

in eukaryotes, proteins called called transcription factors bind to ___ and recruit the ___

A

promoter DNA; RNAP 2

34
Q

many eukaryotic promoters have a sequence called a ___ that plays the role of a promoter

A

TATA box

35
Q

when the TATA is recognized by a TF, allowing other TFs to bind, forming a ___

A

transcription complex

36
Q

once made, a transcription complex recruits ___ to form a__

A

RNAP 2; initiation complex

37
Q

some TFs allow eukaryotes to control the level of ___

A

gene expression

38
Q

some TFs can be activators or repressors: can increase or decrease the likelihood of forming a ___

A

ignition complex

39
Q

activator/repressor TFs bind to __ or __ regions upstream of the DNA strand

A

enhancer; silencer

40
Q

the ___ of DNA is what allows transcription factors at distant binding sites to work

A

flexibility

41
Q

____ catalyses the initiation and elongation of RNA

A

RNAP

42
Q

RNAP requires what 3 components?

A
  1. a template
  2. activated precursors
  3. Mg or Mn cofactor
43
Q

what is the template for RNAP?

A

one of the DNA strands

44
Q

the template strand sequence:

A

complement of that of the RNA transcript

45
Q

the coding strand sequence :

A

same as the RNA transcript, but T in place of U

46
Q

what are the activated precursors?

A

the buliding blocks of the RNA product (ribonuclioside triphosphates)

47
Q

Mg stabilizes ___ and __ on incoming nucleotides

A

beta and gamma phosphates

48
Q

after the promoter region, RNAP ___ a 17-bp segment of the DNA double helix so that nucleotides on the template strand can direct the __

A

unwinds; synthesis of the RNA product

49
Q

elongation takes place at __ that move along the DNA template

A

transcription bubbles

50
Q

what are the 2 main stop singles for transcription in bacteria?

A
  1. rho-independent termination

2. rho-dependent termination

51
Q

what is rho independent termination?

A

the stop signal is an RNA hairpin (series of bases that form a stable stem and loop) followed by several Us

52
Q

what is rho-dependent termination?

A

a rho protein binds the nascent RNA strand and pulls it away from RNA polymerase and DNA template

53
Q

t/f eukaryotic mRNA is highly processed

A

true

54
Q

pre-mRNA acquire a ___ cap and a __ tail and will be spliced by __

A

guanine 5’ cap’ and poly A 3’tail ; introns

55
Q

function of guanine cap

A

prevent deflation and ease translation

56
Q

function of the poly A tail

A

prevent degradation and ease translation

57
Q

poly A polymerase adds about 250 ___ residues to an mRNA after being cleaved after transcription

A

adenylate

58
Q

introns can vary between __ and __ nucleotide

A

50–10 000`

59
Q

a mixture of __ and __ form small nuclear ribonucleoproteins (snRNPs)

A

proteins and small nuclear RNA molecules

60
Q

assembly of 5 snRNPs forms a __

A

spliceosome

61
Q

function of spliceosome

A

catalyze splicing

Biochemistry 2065 (19 decks)

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