06b: RNA Flashcards Preview

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Flashcards in 06b: RNA Deck (46):
1

(DNA/RNA) is the master copy and (DNA/RNA) is the working copy.

DNA; RNA

2

(DNA/RNA) is carefully reproduced and stable.

DNA

3

(DNA/RNA) is constantly synthesized, used, degraded.

RNA

4

The processes of transcription and translation are (X) in prok and (Y) in euk.

X = closely coupled

Y = spatially and temporally separate

5

T/F: the lengths of DNA and RNA are similar.

False - RNA shorter

6

T/F: RNA is always single-stranded.

True

7

(DNA/RNA/both/neither) can form secondary loop and stem structures.

RNA only (ex: tRNA)

8

Abundance of (X) RNA is the greatest. And of (Y) RNA is the least.

X = rRNA

Y = mRNA

9

The unit that defines RNA size (ex:20S) is related to the (X) of the molecule.

X = size and shape

10

In transcription, DNA is read in which direction? And RNA is synthesized in which direction?

Read: 3' to 5'

Synthesis: 5' to 3'

11

Which enzyme creates primer for transcription?

NO PRIMER NEEDED

12

The coding strand is the (X) strand.

X = sense

13

The non-coding strand is the (X) strand.

X = template

14

Bacterial RNA pol has which subunits in core enzyme?

Alpha (2 of them), beta, beta(')

15

RNA pol in bacteria: holoenzyme has which subunits?

Alpha (2 of them), beta, beta('), and sigma

16

Which subunit in prok RNA pol has the catalytic site?

Beta

17

Which subunit in prok RNA pol binds the DNA template?

Beta(')

18

Sigma subunit in prok RNA pol has which function?

Recognizes promoter regions (needed for appropriate initiation)

19

T/F: in genome, either DNA strand can be the template.

True

20

Which steps in transcription are catalyzed by RNA pol?

All (initiation, elongation, termination)

21

The prok promoter region sequences are written on the (X) strand.

X = sense (coding)

22

Once RNA pol binds DNA, an (open/closed)-promoter complex forms.

Closed-promoter complex first, then open-promoter complex

23

Beta subunit on RNA pol has (X) sites for:

X = 2 NT binding sites:

1. For 5' purine
2. For all subsequent NTPs

24

First base in transcription is almost always:

Purine-5'-triphosphate

25

How long does sigma subunit stay bound during transcription?

Released as pol starts to proceed down template

26

How many bp of DNA is unwound in open-promoter complex during transcription?

About 12 bp

27

During transcription, the RNA-DNA hybrid is about (X) bases long.

X = 8

28

What are the requirements for transcription termination that is (X)-independent?

X = Rho

1. Must be GC-rich palindrome
2. Must be followed by UUUUs

29

GC-rich palindrome during (X) forms:

X = Rho-independent transcription termination

Forms hairpin loop

30

String of UUUs during (X) significant because:

X = Rho-independent transcription termination

Form weak AU bonds that can easily break to release RNA transcript

31

Majority of transcription termination cases are Rho-(dependent/independent).

Independent

32

What is Rho?

Large protein that's a helicase and an ATPase

33

List steps of Rho-dependent termination.

1. Rho binds DNA
2. Hydrolyzes ATP and moves down DNA-RNA hybrid (5' to 3')
3. Catches up with RNA pol
4. Helicase unwinds hybrid, releasing RNA

34

Rifampicin is used to treat (X). What's its mechanism?

X = TB

Inhibits formation of first phosphodiester bond in transcription initiation

35

A mutation in which subunit of M. tuberculosis RNA pol would lead to rifampicin-resistant TB?

Beta subunit

36

What are the key differences in euk transcription, compared to prok?

1. Three different RNA pols
2. No sigma subunit
3. Pol-protein interactions, NOT pol-DNA interactions, govern initiation

37

Which RNA pol in euk transcribes mRNA?

Pol 2

38

In euk, the core promoter region is composed of which elements?

1. Basal (-25)
2. Constitutive (-110)
3. Inducible (-150)

39

Basal promoter region function

Determines start site

40

Constitutive promoter region function

Determines transcription rate (based on number and order of these sequences)

41

Inducible promoter region function

Determine specificity of transcription (ex: environment, hormones bind, etc)

42

Euk transcription initiated after which key event?

Phosphorylation of RNA pol 2 by TFIIH (kinase)

43

Euk transcription terminated after which key event?

Dephosphorylation

44

Difference between inducible and constitutive.

Inducible: either on or off, depending on presence of stimulus

Constitutive: always made, but at different rates

45

T/F: genes transcribed by all euk RNA pol have significant regulation.

False - RNA pol 1 and 3 have minimal regulation

46

Alpha-amanitin affects (euk/prok) by:

Euk only;

Inhibits RNA pol 2 (and pol 3 a tiny bit), so no protein synthesis (liver failure, death)