Lecture 5 - Transcription and RNA Processing Flashcards Preview

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Flashcards in Lecture 5 - Transcription and RNA Processing Deck (86)
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1

Do RNA polymerases require a primer?

NOPE

2

Does nascent RNA remain hybridized to template DNA?

NOPE

3

Which is more permanent: RNA or DNA?

DNA

4

Which is more accurate: replication or transcription?

Replication

5

How frequent are errors during transcription?

1 per 10,000 nucleotides

6

Are RNA and DNA polymerases structurally and evolutionarily related?

NOPE

7

Why do many errors during transcription go unnoticed?

Because many RNA strands are synthesized

8

What are mRNAs? Function?

Messenger RNAs

Code for proteins

9

What are rRNAs? 2 Functions?

Ribosomal RNAs

1. Form the basic structure of the ribosome
2. Catalyze protein synthesis

10

What are tRNAs? Function?

Transfer RNAs

Central to protein synthesis as adaptors between mRNA and AAs

11

What are snRNAs? Function?

Small nuclear RNAs

Function in a variety of nuclear processes including the splicing of pre-mRNA

12

What are snoRNAs? Function?

Small nucleolar RNAs

Used to process and chemically modify rRNAs

13

What are scaRNAs? Function?

Small cajal RNAs

Used to modify snoRNAs and snRNAs

14

What are miRNAs? Function?

MicroRNAs

Regulate gene expression typically by blocking translation of selective mRNAs

15

What are siRNAs? Function?

Small interfering RNAs

Turn off gene expression by directing degradation of selective mRNAs and the establishment of compact chromatin structures

16

What is the function of other noncoding RNAs? 3 of them

Function in diverse cell processes like:
1. Telomere synthesis
2. X-chromosome inactivation
3. Transport of proteins into the ER

17

How are different types of RNAs synthesized?

By different types of RNA polymerases

18

Are both DNA strands used as templates during transcription?

Not necessarily

19

How do we call the DNA strand that is not used as the template during transcription? 3 names

Nontemplate strand = coding strand = sense strand

20

In what direction is RNA synthesized during transcription?

5' => 3'

21

How is the template strand assigned?

Functional assignment: called this only when it is serving as the template, which depends on the type of RNA polymerase used and what direction it moves in which is dependent on the direction of the gene

22

How to tell the direction of transcription?

As the RNA polymerase moves the RNA gets longer and longer

23

What is a transcription bubble?

Small strand separation in which the RNA polymerase reads the DNA template strand and synthesizes RNA

24

How is the nascent RNA released by the RNA polymerase?

Released from a ribosomal complex on the RNA polymerase

25

What are the 3 types of eukaryotic RNA polymerases and what types of RNA does each synthesize? Which ones accounts for most of RNA synthesis?

I: 5.8S, 18S, and 28S rRNAs (70% of RNA synthesis)
II: mRNA, snoRNA, and some snRNA
III: tRNA, 5S RNA, some snRNA (for splicing and poly(A)), scRNA (SRP = signal recognition peptide)

26

Which type of RNA is regulated more finely and precisely?

mRNA

27

What is another name for mRNA?

Pol II transcript

28

What are the 2 main differences between bacterial and eukaryotic RNA polymerases?

1. Bacterial RNA pol requires only 1 single protein (sigma factor) for initiation, vs eukaryotic RNA pol require many additional proteins (general transcription factors)
2. Eukaryotic transcriptional initiation must deal with the packaging of DNA in nucleosomes

29

Where is the promoter located? What are its 2 responsibilities? What does this mean for the sequences?

Sequence of DNA that is 5' to the initiation site of the gene: the 5' flanking region, which may also contain enhancers or other protein binding sites

Telling the RNA pol:
1. Where transcription is going to start
2. In what direction transcription should go

Therefore, the promoter is non-palindromic because DNA sequences that are non-palindromic are orientation-dependent and it is also position-dependent

30

What are the 3 regions of the promoter?

1. Distal region
2. Proximal region
3. Core region