Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biol 200 > Lecture 15 - Processing of tRNA and rRNA > Flashcards

Lecture 15 - Processing of tRNA and rRNA Flashcards

1
Q

Principle characteristic of pockets of protein activity/activation

A

No membrane

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

Exemple of pocket of protein activity/activation in the nucleus and what happens there

A

Nucleolus : Transcription and processing of rRNA and tRNA

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

What plays an important role in pre-tRNA/pre-rRNA folding for further processing

A

Their untranslated regions

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

% of transcripts that are rRNAs in a proliferating cell and why

A

80% rRNA transcripts because need ribosomes -> effective translation

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

mRNA tends to distinguish ____________

A

cells from one another

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

tRNA and rRNA (so Pol I and Pol III) ensure the function of the ___________

A

transcription (and translation) machinery

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

Why do we say that rRNA acts similarly to snRNA and what does it do

A

Because interacts with a protein complex (and this complex will translate mRNA)

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

Where pre-tRNAs are processed (like cytoplasm …)

A

nucleoplasm

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

What are nuclear bodies

A

Functional specialized regions where interacting proteins form self-organized structures

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

On EM image, we can see nascent RNP. How/where is it visible and why

A

Visible at 5’ end of each pre-mRNA being transcribed because site of concentrated proteins (for capping in this case)

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

Large precursor pre-RNA transcribed by RNA Pol I -> what are the three kinds of changes it undergoes

A

Cleavage, exonuclease digestion, base-pair modifications

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

Large precursor pre-RNA : what its changes lead to

A

it yields mature 28 S, 18 S and 5.8 S rRNAs

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

What 28S, 18S and 5.8S RNAs associate with and where

A

With ribosomal proteins, in the nucleolus

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

What leads to the attraction of proteins together to form the nucleolus (what drives that, why do they do that)

A

Transcription (and therefore processing of rRNA, tRNA)

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

Proteins that gather to the nucleolus : what do they gather around and why

A

Around RNA to form a functional machine

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

To what extent 18S, 5.8S and 28S are preserved

A

Preserved in size across all types of eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is found on pre-rRNA (large precursor rRNA) from 5’ to 3’)

A

Preserved regions of rRNA (that are, from 5’ to 3’ : 18S, 5.8S, 28S) and between them, transcribed spacer regions

18
Q

Transcribed spacer regions : conserved to what extend + their functions (2)

A

Not conserved.
Help for transcript folding and recognition by methylase or protein complexes required (function in maintenance of spatial dynamic)

19
Q

Two main things that happen to pre-rRNA when processed

A

1) Complexes consisting of 70-80 prots attach and process the 5’ end
2) Sequence in the transcript is changed by methylation and pseudouridylation events

20
Q

What directs the modifications of the pre-rRNA

A

snoRNPs (small nucleolar RNP)

21
Q

How snoRNP recognizes pre-rRNA and what this ultimately leads to

A

Has specific regions/adresses that the protein complexes attached to pre-rRNA recognize and the snoRNP identifies certain residues in the transcript

22
Q

3 known modifications that pre-rRNAs undergo at the snoRNP

A

Ribose methylation, pseudoudirylation and uridine-pseudouridine conversion

23
Q

How many known conserved sequences in snoRNPs

A

none

24
Q

When pre-rRNA is processed

A

As it is being transcribed

25
Q

What part of the snoRNP recognizes the pre-rRNA and what part does the modifications

A

snoRNA part recognizes the pre-rRNA

Enzymes/Proteins of the snoRNP do the modifications

26
Q

What happens during ribose methylation (attraction and how/why methylation occurs)

A

snoRNA makes a finger that attracts pre-rRNA : they base-pair. A methylase recognizes this structure due to the folding of the pre-rRNA due to presence of transcribed spacer regions.

27
Q

What happens during pseudouridylation (attraction and how/why modif occurs)

A

snoRNA makes a finger with a hub in the middle : pre-rRNA hybridizes there.
Enzymes recognize this structure and will modify it

28
Q

What happens (chemically) during uridine-pseudouridine conversion

A

An enzyme flips the C and the N

29
Q

Modifications of tRNA (2) in the nucleus and how this is possible (what must happen during transcription)

A

1) Cleavage of 5’ end and 3’ end
2) Addition of CCA on 3’ end
2) Base modifications
Must be transcribed with extra parts

30
Q

Why tRNAs have to be precise

A

Carry a specific amino acid and a specific anticodon

31
Q

First 5’ end sequence found in tRNA : 2 functions

A

1) Folding of the tRNA

2) Recognition by tRNA synthetase

32
Q

What happens to first 5’ end sequence in tRNA after doing its job

A

It is lost

33
Q

What happens to excess nucleotides in the tRNA after transcription and folding

A

Excess nucleotides are degraded (it’s the reason why 5’ end sequence is gone/now shorter)

34
Q

What happens to the 3’ end of the tRNA during processing

A

CCA tail is added (from 5’ to 3’)

35
Q

What happens to residues within the stem loops of the tRNA during its processing + major event

A

Are replaced + lot of replacement in the anticodon loop with inosine by an enzyme complex

36
Q

When can enzyme complexes interact with the anticodon loop of the tRNA

A

When the tRNA has a proper structure (this allows processing)

37
Q

Basic principle of ribosome formation (what molecules are involved)

A

rRNA and tRNA with proteins form essential complexes of the ribosome

38
Q

Summary of what happens during tRNA processing (3 things)

A

1) 5’ end for folding + tRNA synthetase recognition + is lost (excess residues removed)
2) 3’ end cleaved and CCA added at 3’ end
3) Residues in stem loops replaced + anticodon loop : major replacement with inosine involving enzyme complex

39
Q

Principle purpose of intervening regions (3 things they do)

A

Help for folding, help for recognition by protein complexes + are lost afterwards

40
Q

2 things protein complexes do for tRNA

A

Process it to make it functional and move it to the cytoplasm

41
Q

Meaning of dark region on EM image (link with nuclear bodies)

A

More concentrated in proteins

42
Q

What region of the tRNA will bind amino acids

A

CCA at 3’ end

Biol 200 (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions