Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Cell and Molecular Biology > RNA synthesis > Flashcards

RNA synthesis Flashcards

1
Q

What is transcription?

A

Process of RNA synthesis from a DNA template

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

What is the central dogma?

A

DNA -> RNA -> Protein

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

What are the four RNA types?

A

mRNA
tRNA
rRNA
Noncoding RNAs

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

What is mRNA?

A

Codes for proteins, makes uo 3 to 5% total RNA

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

What is tRNA?

A

participates in translation, there are 49 families, each carries an amino acid and has a specific anticodon loop

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

What is rRNA?

A

ribosomal RNA, major constituent of ribosomes, There are 4 main types

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

What are noncoding RNAs?

A

Serve as structural and enzymatic functions

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

What are the four major differences between RNA and DNA?

A

1) Contains ribose instead of deoxyribose
2) Contains U instead of T
3) Synthesised as a new strand
4) RNA is very unstable

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

What is the structural difference between deoxy-ribose and ribose?

A

Deoxyribose does not have an OH group at C3, just has a H

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

Which bases pair up in RNA?

A 
U = A
G = C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is non Watson Crick pairing and can it occur in RNA

A

Where the pairs do not pair according to the watson crick rule ie G = U
Yes it can occur

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

What is the secondary structure of RNA like?

A

It forms stem-loop secondary structures

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

What is RNA tertiary structure?

A

Where the RNA folds into a three dimensional shape

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

What are RNA polymerases?

A

The enzymes which perform RNA synthesis

There are 3 types in eukaryotes

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

What are the 3 types of RNA polymerases?

A

RNA polymerase I, II and III

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

What is RNA polymerase I?

A

only transcribes ribosomal RNA

Accounts for 50% of RNA polymerases

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

What is RNA polymerase II?

A

Protein encoding genes

Transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is RNA polymerase III?

A

The genes transcribed are”housekeeping” genes
Regulation primarily tied to the regulation of cell growth and the cell cycle
eg tRNA, small nuclear RNA and 5S rRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which rRNA does RNA polymerase I not transcribe?

A

5s rRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

True or false - only one RNA polymerase molecule can bind to a gene at anyone time

A

False - multiple RNA polymerases can bind on the same gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Is a primer needed for RNA synthesis?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How many strands are used as a template for RNA synthesis?

A

Only one strand is used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Does the RNA transcript remain bound to the DNA template?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe an issue with RNA synthesis compared to DNA synthesis

A

There is a much higher error rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How does RNA polymerase act on the DNA double helix?
It unwinds it
26
Give 5 differences between DNA replication and RNA synthesis
1) No primer needed 2) Only one strand of DNA is used as the template 3) Transcript does not remain bound to template 4) Higher error rate 5) Multiple RNA Pol bind on the same gene
27
What are the two directions RNA polymerase can run?
Left to right - 5' to 3' | Right to left - 3' to 5'
28
Why does RNA polymerase run in both directons?
Genes can be on either strand of the DNA
29
The movement that RNA polymerase takes determines what?
Which of the 2 DNA strands serves as a template for the synthesis of RNA
30
How is the polymerase direction determined?
By the promoter sequence
31
What is the promoter sequence?
The site at which RNA polymerase begins transcription
32
What is supercoiling?
The creation of a super helix
33
If DNA with a fixed end unwinds 10 DNA base pairs what happens?
The DNA helix must rotate one turn
34
If DNA with fixed ends unwinds 10 DNA base pairs what happens?
DNA helix forms one supercoil
35
What is the role of topoisomerases?
They release supercoils to allow progression of RNA synthesis
36
Where does transcription for a gene start?
At its promoter | Sequences in the DNA tell RNA polymerases where to start transcription
37
What are the promoter elements for RNA polymerase 2?
BRE - GCGCG (Lots of Gs and Cs) TATA - TATA (Lots of Ts and As) INR - CANT DPE = AGAG
38
What are the general transcription factors for each of the RNA polmerase II promoter elements
``` BRE = TFIIB TATA = TBP (TATA binding protein) INR = TFIID DPE = TFIID ```
39
Where does the TATA binding protein bind to?
Directly to the DNA ie it binds on to the TATA box
40
TBP is a subunit of what?
TFIIB
41
How many nucleotides does the TATA box usualy lie upstream from the transcription start site?
25
42
What are the two important roles of the TATA box?
It is the DNA sequence that signals the start if transcription Binding of TFIID causes distortion of the DNA = physical landmark for the location of an active promoter
43
What is formed once a transcription factor has bound to DNA?
A transciption initiation complex
44
Which proteins does a transcription initation complex consist of?
``` General Transcription factors RNA polymerases Mediators Chromatin remodelling complexes Histone acetlyases ```
45
How many proteins are there in the complex?
Over 100
46
What are the 3 ways RNA is processed?
Splicing of introns Capping of the 5' end Polyadenylation
47
What is splicing?
Where non coding regions of mRNAs are eliminated ti generate mature mRNA for protein synthesis
48
Why is 5' end capping done?
Neccessary for stability, binding of mRNA to ribosomes and initiation of translation
49
What is polyadenylation of the 3' end?
Part of the termination process (addition of the Poly-A tail) Determines mRNA stabilty, helps mRNA nuclear export and translation
50
Splicing is specific to what type of cell?
Eukaryotes
51
Where are introns and exons both present?
In DNA and pre-mRNA
52
What is it called when mRNA is spliced in more than one way?
Alternative splicing
53
What are the steps involved in splicing?
1) The 5' OH of the branch site in the intron attacks a phosphodiester bond on donor site G 2) Cleavage at the donor site forms a lariat 3) 3' OH of the donor site attacks a phosphodiester bond on acceptor site G freeing the lariat 4) The lariat is degraded
54
What is a spliceosome?
Large and complex molecular machine Assembled from snRNAs and SR protein. Removes introns from a transcribed pre-mRNA
55
What is the spliceosome structure?
Nuclear complex made of about 150 proteins plus 5 RNAs
56
What are the three functions of the spliceosome?
1) Recognise the 5' donor and branch sites 2) Bring these sites together 3) Catalyses RNA cleavage
57
Which mRNAs have a 5' cap?
All eukaryotic mRNAs
58
When is the cap added?
When mRNA is 20-40 nucleotides long
59
What is unusal about the 5' cap?
It has a 5' to 5' linkage of guanosine
60
What happens to the guanine in the 5' cap?
It is methylated
61
Where does mRNA cleavage occur after the polyA signal?
About 10 to 30 nucleotides downstream
62
What is the polyA signal?
AAUAAA
63
Up to how many A can be added?
200
64
Polyadenylation only occurs on products of which RNA polymerase?
RNA polymerase 2
65
What is the role of CPSF?
It catalyses the cleavage of the mRNA 10 to 30 nucleotides downstream of the complexes binding site

Cell and Molecular Biology (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions