RNA Part 2 Flashcards

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1
Q

Key differences in transcription between eukaryotes and prokaryotes

Genes and their spacing?

A

Eukaryotes typically have more genes that are spaced further apart

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2
Q

Key differences in transcription between eukaryotes and prokaryotes

RNA pol?

A

Eukaryotes have 4 RNA polymerases
Prokaryotes have 1

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3
Q

Key differences in transcription between eukaryotes and prokaryotes

What do eukaryotes have the prokaryotes dont?

A

Nucleus

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4
Q

How is DNA in eukaryotes packaged?

A

Into chromatin

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5
Q

In eukaryotes, _ are exported from the nucleus prior to translation

A

Transcripts

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6
Q

What are the 3 RNA polymerases

A

RNA pol I
RNA pol II
RNA pol III

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7
Q

RNA pol I responsibility

A

Recruits the ribosome and rRNA
rRNA genes except 5s

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8
Q

RNA pol II responsibility?

A

Transcribes protein-coding genes and a variety of noncoding RNAs

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9
Q

RNA pol III responsibility

A

tRNAs, some snRNAs, 5s rRNA

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10
Q

Most eukaryotes have multiple if not many, _ copies of rDNA genes

A

tandem

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11
Q

RNA pol II recruitment and activation

What is a preinitiation complex (PIC) ?

A

A number of general transcription factors cooperate to form the PIC

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12
Q

What does the PIC do?

A

PIC recruits additional transcription factors and RNA pol II

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13
Q

How do you enable elongation?

A

A kinase phosphorylates RNA pol II and other proteins to enable elongation

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14
Q

What does the architecture of RNA pol III recruitment and activation depend on?
What does that mean?

A

Depends on the promoter type.
Different promoters regulate different genes

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15
Q

What is RNA pol II regulated by?

A

RNA pol II is regulated at multiple steps by carboxyl-terminal domain (CTD) posttranslational modification

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16
Q

How many models did we go over for how RNA pol II terminates

A

2

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17
Q

First model of RNA pol II termination?

A

An exonuclease causes RNA pol II to dissociate

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18
Q

Second model of how RNA pol II terminates?

A

The cleavage of mRNA causes a conformational change in RNA pol II

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19
Q

What are RNA pol II transcripts capped with at the 5’ end?

A

Capped with 7-methylguanosine to provide protection

20
Q

What does 5’ end capping involve?

A

Capping involves the sequential action of 3 enzymes associated with the CTD

21
Q

How are the 3’ end of RNA pol II transcripts protected?

A

Protected by polyadenylation, poly-A binding proteins come in and protect the 3’ end

22
Q

Addition of the poly-A tail involves _ of the mRNA followed by polyadenylation

A

Cleavage

23
Q

mRNA splicing

What acts at the 5’ splice junction?

A

u1 small nuclear ribonucleoprotein
snRNP

24
Q

mRNA splicing

Normal splicing involves specific pairing between

A

U1 snRNA and the splice site

25
Q

mRNA splicing

What could disrupt splicing

A

Mutations at the splice site

26
Q

What can suppress some splice site mutations?

A

Secondary mutation in the U1 snRNA

27
Q

What do U1 and U2 snRNPs enable?

A

They enable the formation of the spliceosome and intron excision

28
Q

How does splicing proceed?

A

Through a series of transesterification reactions

29
Q

What organisms have self-splicing introns?

A

Some bacteria, viruses and nuclear-encoded organellar genes

30
Q

What are self-splicing introns?

A

Ribozymes

31
Q

What does alternative splicing produce?

A

Related but distinct protein isoforms

32
Q

In eukaryotes, how can a single gene produce a variety of transcripts?

A

Splicing makes this possible

33
Q

A single pre-mRNA that contains exons and introns can be _ in a myriad of patterns

A

spliced

34
Q

What enables the formation of spliceosome and intron excision?

A

U1 and U2 snRNP

35
Q

Splicing proceeds through a series of _ reactions

A

Transesterification

36
Q

What organisms have self splicing introns

A

Some bacteria, viruses and nuclear encoded organellar genes

37
Q

Self-splicing introns are _

A

ribozymes

38
Q

How can you produce distinct protein isoforms?

A

Alternative splicing

39
Q

In eukaryotes, how is it possible for a single gene to produce a variety of transcripts

A

Splicing makes this possible

40
Q

a single pre-mRNA that contains exons and introns can be spliced in a myriad of _

A

Patterns

41
Q

There are _ mechanisms for mRNA decay in eukaryotes

A

multiple

42
Q

_ or _ RNA can result in gene silencing

A

Exogenous or ectopic

43
Q

How are small interfering RNAs (siRNAs) produced ?

A

By hairpin or double stranded RNAs

44
Q

_ processes siRNAs to enable them to complex with _

A

Dicer
Argonaute (Ago)

45
Q

The Ago complex is further processed and is able to target the _ _

A

Complementary mRNA