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UNION > BIO 205 TRANSCRIPTION > Flashcards

BIO 205 TRANSCRIPTION Flashcards

1
Q

what is transcription

A
  • RNA synthesis

* creating of single-stranded molecule on way to being translated into functional model

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2
Q

where does transcription occur in prokaryotes

A

cytoplasm SAME TIME AS TRANSLATION

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3
Q

where does transcription occur in eukaryotes

A

nucleus

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4
Q

RNA diff from DNA

A
  • uses uracil not thymine (U-A)

* single-stranded

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5
Q

RNAs can form secondary structures via ___

A

intramolecular interactions

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6
Q

types of RNA in eukaryotes

A

major- mRNA: intermediate transient products (short time)

rRNAs, tRNAs, and snRNAs : final products

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7
Q

mRNA stands for

A

messenger RNA

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8
Q

rRNA stands for

A

ribosomal RNA

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9
Q

tRNA stands for

A

transfer RNA

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10
Q

snRNAs stands for

A

small nuclear RNA

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11
Q

All eukaryotic RNAs are created by

A

3 types of RNA Polymerases

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12
Q

DNA polymerase and RNA polymerase differ?

A

DNA polymerase
• synthesizes a DNA strand
• used in DNA replication
• faster

RNA polymerase
• transcription to synthesize the mRNA strand (not H-bonded to the DNA template)
• doesn’t need primer
• no proofreading
• 10x slower
• not all regions of DNA transcribed, only coding region

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13
Q

properties of RNA Polymerase

A
  • uses ribonucleoside triphosphates (ATP, CTP, GTP, UTP) and Mg++
  • 5’ –> 3’ phosphodiester bonds
  • needs template DNA strand
  • RNA is complementary to template
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14
Q

RNA polymerase transcribing for how long

A

short time

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15
Q

coding strand also called

A

sense strand

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16
Q

template strand also called

A

antisense strand

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17
Q

coding strand …

A

specifics amino acid sequence of protein

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18
Q

template strand …

A

where RNA is actually transcribed

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19
Q

coding and template formation:

A

asymmetric transcription

mRNA: 5’ —–> 3’
template: 3’ 3’

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20
Q

gene regions controlling transcription

A
  1. PROMOTER : “upstream” - 5’ controlling region

2. TERMINATOR : “downstream” - 3’ controlling region

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21
Q

prokaryotic promotor

A
  • promoter: a key point of regulation for transcription
  • consensus sequences (can change slightly)
  • provide binding site for RNA polymerase
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22
Q

prokaryotic promotor elements

A

TATA BOX/Pribnow box @ -10

-35 box

23
Q

prok. TATA BOX aka:

A

Pribnow box

24
Q

prok. TATA BOX is where?

A

-10

25
Q

prokaryotic promoter numbers

A

-10, -35

26
Q

consensus analysis

A

can change very slightly

• defines target regions

27
Q

“Wreck and Check”

A

1- mutate specific region

2- check if transcription affected

28
Q

why does mutation work better than wild type

A
  • promoter is never turned on all the way

* only need enough to repair

29
Q

eukaryotic promoter numbers

A

-25, -75

30
Q

euk. TATA box aka:

A

Hogness box

31
Q

euk. TATA box is where?

A

-25

32
Q

structure of E. coli RNA Polymerase

A

• core enzyme consists of 5 subunits

Core Enzyme + Sigma Factor
= HOLOENZYME

33
Q

3 phases of transcription

A

initiation, elongation, termination

34
Q

differences between prokaryotic and eukaryotic polymerase binding

A
  • prokaryotic RNA Polymerase binds to the DNA template directly
  • eukaryotic RNA Polymerase requires co-factors
35
Q

transcription of Prokaryotes

A
  • Initiation: RNA polymerase recognizes promoter; starts the transcription
  • Elongation: RNA strand continuously grows
  • Termination: RNA polymerase stops synthesis and nascent RNA separates from DNA template
36
Q

Initiation in Prokaryotes

A
  • no primer for RNA synthesis
  • sigma factor associates with core enzyme (HOLOENZYME) and begins searching for promoter
  • finds promoter, binds between -10 and -35 (ALL)
  • sigma factor falls of RNA pol. when first phosphodiester bond is formed
  • core enzyme moves along for elongation
37
Q

Eukaryotic Transcription Initiation

A

• needs many transcription factor proteins

38
Q

how much does RNA Polymerase unwind

A

17 base pairs, doesn’t need ATP

39
Q

transcription: ELONGATION

A
  • can be transcribed simultaneously from the same segment of DNA
  • core enzyme slides on the DNA template toward the 3’ end
  • Free NTPs added sequentially to the 3’-OH of the nascent RNA strand
40
Q

elongation - release of the Sigma factor causes…

A

• conformational change to core enzyme

41
Q

NTP

A

nucleoside triphosphate

42
Q

RNA Polymerase Enzyme

A
  • One core enzyme complex synthesizes the whole RNA chain (it is 100% processive)
  • RNA polymerase has no editing activity – more error-prone
43
Q

Termination

Prok.

A
  • RNA polymerase stops moving on DNA template
  • RNA transcript falls off transcription complex

• occurs in either: Rho-dependent or Rho-independent

44
Q

Rho-INDependent
versus
Rho-Dependent

A
  • INDEPENDENT: RNA forms a hairpin loop, causes RNA polymerase to pause, allowing Rho protein to catch up, and displace RNA polymerase from the template – STOPPING transcription
  • DEPENDENT: rho protein disassociates the RNA Polymerase and moves it off of template
45
Q

Inhibitors of Transcription

A
  • Rifamycin B:
  • Actinomycin D:
  • a-Amanitin: (poisonous mushrooms)
46
Q

what is Rifampin used to treat

A

TB, leprosy, meningitis

47
Q

Rifamycin B:

A

inhibitor of prokaryotic transcription
(not eukaryotes)
– an antibiotic [Rifampin]
- stops chain elongation after first phosphodiester bonds formed
- remains bound to the promoter, blocking other enzymes
transcription and replication

48
Q

Actinomycin D:

A

elongation inhibitor for both euk and prok – binds tightly to duplex DNA, inhibiting transcription and replication

49
Q

a-Amanitin

A

(poisonous mushrooms)
- forms tight complex w eukaryotic RNA pol II and lose complex w RNA pol III
- blocks elongation steps in eukaryotes
• RNA polymerase I, mitochondrial, & prokaryotic RNA polymerases are insensitive to a-amanitin

50
Q

Eukaryotic Promoter Elements

A

TATA Box
CAAT Box
GC Elements

51
Q

CAAT Box

A

eukaroytic @ -75

52
Q

Eukaryotic transcription factors

A

• TBP = TATA-Binding
Protein
• is part of TFIID = Transcription factor II D

• Involves many transcription factor proteins instead of just sigma factor

53
Q

(eukaryotic) Enhancer

A

(on strand) binding site for activator protein

UNION (10 decks)

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