Brainscape's Knowledge GenomeTM

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


See full index

PHA111 > Translation > Flashcards

Translation Flashcards

1
Q

What is translation?

A

The synthesis of a protein from a transcribed sequence into mRNA

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

Where does translation occur?

A

cytoplasm

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

In prokaryotes (70S), translation is __-_________

A

co-transcriptional

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

In eukaryotes (80S), translation occurs after _______

A

transcription

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

How big is a ribosome?

A

10nm

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

The different units of ribosome are characterised based on the rate at which they sediment (measured in S) in a _______

A

centrifuge

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

What does the small ribosomal subunit contain?

A

Decoding centre needed for reading mRNA

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

What does the large ribosomal subunit contain?

A

Catalytic RNA-peptidyl transferase centre

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

What is a polyribosome?

A

Multiple ribosomes on an mRNA strand

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

tRNA carries amino acids that occupy A,P and E sites that occur mostly in the large/small subunit, but are completed in the large/small subunit

A

large

small

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

What is the A site?

A

acceptor site where amino-acyl tRNA lands

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

What is the P site?

A

Peptidyl tRNA site occupied by the last amino acid

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

What is the E site?

A

exit site where tRNA leaves

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

What is tRNA?

A

Adaptor molecules that deliver amino acids to the ribosome

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

What is the secondary structure of tRNA?

A
  • clover leaf shape

- contains intra-tRNA H-bonding sites

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

The specific sequence of the anticodon is ________ to a sequence on mRNA

A

complementary

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

What are codons?

A

3 nucleotide triplets

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

Describe the method of the Nirenberg experiment

A
  • They synthesised mRNA with repeating nucleotides, and they added these to a test tube containing E.coli lysate.
  • The proteins were isolated to see which amino acids were incorporated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What were the results of the Nirenberg Experiment

A

UUU is an mRNA codon for phenylalanine
AAA is an mRNA codon for lysine
CCC is an mRNA codon for protine

A triplet codon based on 3 base codons determines amino acids

20
Q

List the 3 stages of translation in prokaryotes

A
  • Initiation
  • Elongation
  • Termination
21
Q

Define translocation

A

Movement of a ribosome along mRNA

22
Q

What does the initiation complex of translation include?

A
  • ribosome
  • mRNA
  • initiator tRNA
23
Q

Initiator tRNA recognises the ____ codon and enters the __- site, and the following tRNA’s only enter the __-site

A

AUG
P
A

24
Q

What else is required for initiation?

A
  • 3 initiation factors

- GTP

25
Q

What 3 steps are involved in elongation?

A
  • Peptide bond formation
  • Translocation
  • Aminoacyl-tRNA delivery
26
Q

After initiation, the __-site is occupied whilst the __-site is empty

A

P

A

27
Q

3 elongation factors are recruited to the initiation complex and they can all bind to ___ or ___

A

GTP or GDP

28
Q

What do elongation factors do?

A
  • delivers aminoacyl-tRNAs
  • generates release of EF-Tu-GDP complex
  • Translocation uses energy from GTP hydrolysis to eject tRNA from P-site, and move peptidyl-tRNA into the P-site from the A-site
29
Q

How is frameshifting prevented?

A

The ribosome complex maintains a 6bp contact with the mRNA

30
Q

When does elongation stop?

A

When a termination codon appears at the A-site

31
Q

What is the process called in which the ribosome dissociates from the mRNA?

A

Termination

32
Q

Protein release factors (RF) interact with these termination codons to release the polypeptide chain.
Describe what each RF does

A
  • RF 1 - recognises UAA + UAG
  • RF 2 - recognises UAA + UGA
  • RF 3 - facilitates RF 1 + RF 2
33
Q

RF causes ____________ to transfer the polypeptide to water so the protein is released

A

peptidyltransferase

34
Q

RF dissociates the ribosome complex from the _____ and removal of tRNA from __-site

A

mRNA

P

35
Q

What is co-translation?

A

When transcription and translation occur simultaneously.

36
Q

What is an example of a co-translational control?

A

Tryptophan operon (trp operon)

37
Q

What is the trp operon?

A

Group of genes that encode enzymes for Tryptophan

38
Q

When is the trp operon expressed?

A

When tryptophan levels are low

39
Q

When is the trp operon repressed?

A

When tryptophan levels are high

40
Q

What regulates the trp operon?

A

trp repressor

41
Q

How does the trp repressor work?

A

When bound to tryptophan the trp repressor blocks expression from the operon

42
Q

What is attenuation used as?

A

A control mechanism when tryptophan levels are high and stops ribosome progressing along the mRNA

43
Q

The attenuator polypeptide contains 2 tryptophan residues. What happens if there is NO tryptophan?

A

The ribosome stalls and an anti-terminator hairpin follows allowing transcription and translation to proceed

44
Q

What happens if there is a lot of tryptophan?

A

The mRNA stalls and stops due to the terminator hairpin

45
Q

What are the sequences needed to generate anti-terminator and terminator?

A

anti-terminator - 2 +3

terminator - 3 + 4

46
Q

List the properties of proteins

A
  • contain C,H,O,N
  • can absorb light in the UV range
  • contain charged/uncharged/hydrophilic/hydrophobic amino acids

PHA111 (23 decks)

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