Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

GN 311 > Lec 20 > Flashcards

Lec 20 Flashcards

1
Q

Prokaryotic vs. Eukaryotic Transcription

A

Prokaryotic:

  • Polycistronic mRNA
  • no introns (usually)
  • One RNA polymerase

Eukaryotes:

  • Monocistronic (usually)
  • introns
  • 3 RNA polymerase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Transcription: Synthesis of RNA

A
  • DNA used as template
  • No primer needed
  • rNTPs (no thymine, uracial pairs with adenine)
  • Nucleotides are added 5’-3’
  • Two phosphate groups are cleaved from the incoming rNTP as the nucleotide is added
  • RNA polymerase joins the nucleotides together
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What RNAs are transcribed in both prokaryotes and eukaryotes

A

mRNA
rRNA
tRNA

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

What RNAs are only produced in eukaryotes

A 
pre-mRNA
snRNA
snoRNA
scRNA
miRNA
siRNA
piRNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are other names for contemplate DNA strand

A

sense strand or coding strand

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

TorF:Different genes can be transcribed from different strands of the same DNA segments

A

True

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

Transcription unit

A

is segment of DNA that codes for an RNA molecule and the sequences necessary for its transcription

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

Transcription

A

process of making RNA from DNA (5’-3’)

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

what joins nucleotides together in transcription?

A

phosphodiester bonds

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

RNA polymerase

A

enzyme that joins nucleotide together

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

Template strand

A

strand of DNA that is transcribed

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

coding strand

A

other DNA strand: sequence is the same as the RNA transcribed from the template strand except for T/U difference

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

Upstream

A

sequences after the start of transcription

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

Downstream

A

sequences after the start of transcription

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

where does transcription start at?

A

+1 nucleotide

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

What are the four stages of transcription? and which stages require holoenzyme or core enzyme

A
  1. template bind (holoenzyme)
  2. chain initiation (holoenzyme)
  3. chain elongation (core enzyme)
  4. chain termination (core enzyme)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

holoenzyme vs core enzyme

A

holoenzyme contains the sigma factor

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

What are the control regions located in the Promotor?

A

Pribnow Box- 5’-TATAAT-3’

-35 Control Region 5’- TTGACA-3’

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

Consensus Sequence?

A

a sequence that describes the nucleotides most often present in a segment of interest

Y=pyrimidine
R=Purine
N=any

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

Which strand are consensus sequences located on?

A

coding strand

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

Template binding and initiation

A

holoenzyme bind to promoter forming closed complex(has to happen in the proper place)
-the DNA strands separate forming open complex

22
Q

After template binding and initiation what happens?

A 
Sigma dissociates (forming core enzyme) after about 9-12 nucleotides are joined to form RNA 
-Elongation occurs 5'-3' using only coreenzyme
23
Q

What is transcription reaction catalyzed by

A

RNA polymerase

24
Q

Direct vs. Inverted repeats

A

Direct repeats- sequences are the same on either side

inverted repeats- same sequences but are the same but backwards at the diagonal location
-leads to hairpin formation on the RNA during transcription

READ 5’-3’

25
Q

Termination

A

May or May not require RHO

  • inverted repeats are present on the DNA sequence near termination and are transcribed
  • these form hairpin structures in the RNA that can signal termination of transcription
  • The hairpins are followed by a STRING OF ADENINE RESIDUE ON THE TEMPLATE STRAND OF THE DNA. The A-U bonds are relatively weak and allow dissociation of the DNA-RNA pairing (allows two DNA strands to come back together)

-Hairpin causes RNA polymerases to pause

26
Q

Termination using RHO

A

The inverted repeats and adenine residue sequence are still present on DNA and still transcribed

  • RHO binds to the RNA and moves toward the 3’ ned and RNA polymerase
  • RNA polymerase pauses at termination hairpin
  • Rho has helicase activity that causes the DNA-RNA hybrid to unwind and transcription ends
27
Q

Prokaryotic mRNA:Shine-Dingrano sequence

A
  • found in the leader region (not translated)
  • is important for ribosome binding
  • the sequence is about 7 nuts upstream from the start of translation
28
Q

Polycistronic mRNA

A

1 RNA molecule is produced, but it contains the information for more than one gene and is translated into more than 1 gene product

29
Q

Transcription in Eukaryotes: 3 RNA polymerases

A

RNA polymerase I- large rRNA (28s, 18s, 5.8s)
RNA polymerase II- mRNA, most snRNA, snoRNA, miRNA
RNA polymerase III- small rRNA (5s), tRNA, some nRNA

-recognize different promoters, different transcription factors and different termination factors

30
Q

hnRNA

A

heterogeneous RNA=pre-mRNA=precursor for mRNA= primary transcript for mRNA

31
Q

Where does transcription occur in eukaryotes

32
Q

Does mRNA processing occur in eukaryotes or in prokaryotes?

A

eukaryotes

33
Q

What transcribes the transcription unit of rRNA genes in Eukaryotes?

A

RNA polymerase I

34
Q

NTS

A

non-transcribed spacer- contains control region, promoter, and terminators

35
Q

ETS

A

external transcribed space- at ends of transcription unit

36
Q

ITS

A

internal transcribed spacer- within transcription unit

37
Q

rDNA transcription unit

A

transcribed into 1 pre-rRNA molecule then undergoes processing

38
Q

cis Elements

A
  • nucleotide sequence that are close to the coding region of a gene and help the cell to determine when the gene should be transcribed
  • binding spots for proteins (or RNAs)
39
Q

trans-acting factors

A
  • proteins of RNAs from other genes
  • attach to cis-elements or other transcription factors
  • Recruit RNA polymerase
40
Q

What does RNA polymerase II transcribe?

A

pre-mRNA, pre-mRNA, and some snRNA

41
Q

TATA Box

A
  • promoter element
  • near -25
  • consensus sequence read off non-template strand is 5’-TATAAA-3’
  • Part of the core promoter-important in initiation of tx
42
Q

CAAT Box

A
  • promoter element
  • near -80
  • important of initiation of TX
  • consensus 5’-GGCCAATCT-3’
43
Q

GC box

A

Promoter element

  • may have more than 1 and location varies
  • help RNA polymerase bind near sit of TX (transcription)
  • consensus sequence 5’-GGGCGG-3’
44
Q

Octamer BOx

A

promoter element

  • consensus 5’-ATTTGCAT-3’
  • helps RNA polymerase bind properly in initiation
  • location varies
45
Q

Enhancers

A

more distant element NOT a promoter element
-required for maximum transcription
-can function in either direction and from a “distance”, but on same piece of DNA transcriptional activators bind enhancers to help them interact with transcription factors at the start site for TX
(CIS ACTING)

46
Q

Core promoter

A

immediately upstream of gene and where the basal transcription apparatus binds. Has TATA box

47
Q

Regulatory promoter

A

immediately upstream of core promoter. Variety of consensus sequences (Octamer box, GC box, CAAT box)

48
Q

Elongation in Eukaryotes

A

after -30 BP are synthesized, RNA polymerase leaves the promoter and begins elongation

  • Many transcription factors stay bound at the promoter to reinitiate transcription
  • transcription bubble contains about 8bp of DNA-RNA hybrid
  • The structure of the RNA polymerase causes seperation of the newly formed RNA strand from the DNA template Strand
49
Q

Initiation Eukaryotes

50
Q

RatI exonuclease

A

required for termination of transcription

-once RNA is cleaved the RatI binds and degrades the trailing RNA

51
Q

What are the 3 processes of pre-mRNA to form mRNA

A
  • removal of introns
  • polyA tail added to 3’ end
  • capping of 5’ end
52
Q

RNA polymerase III in eukaryotes

A

transcribes tRNA, 5s rRNA, and most snRNAs

  • promoter is located within the gene for the RNA
  • 2 conserved “boxes” that are important for proper transcription

GN 311 (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions