Brainscape's Knowledge GenomeTM

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


See full index

Molecular biology > Translation > Flashcards

Translation Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what is a codon

A

3 consecutive nucleotides in mRNA that codes for one amino acid

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

what is an anticodon?

A

3 consecutive nucleotides in tRNA that is complimentary to the nucleotides of a specific codon

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

what is start codon?

A
  • 3 consecutive nucleotides in mRNA that indicates initiation of translation
  • AUG:
    • ​codes for methionine in eukaryotes
    • formylmethionine in bacteria
  • the first codon of mRNA translated by ribosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is stop codon

A
  • 3 consecutive nucleotides in mRNA that indicates termination of translation
  • UAA, UAG or UGA (GUG, UUG are also stop codons in bacteria)
  • not translated by ribosome
  • binds to release factors instead of tRNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how do codons code for amino acids?

A
  • codon has complimentary anticodon on tRNA
  • codon codes for the amino acid through binding to complimentary anticodon on tRNA
  • tRNA act as adaptor between codon and the amino acid it codes for
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is a ribosome

A
  • large ribonucleoprotein that has petidyle transferase activity
  • active site composed of RNA => it’s a ribozyme
  • translate mRNA transcript into amino acid sequence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

the structure of ribosome?

A
  • large subunit (LSU): peptidyl transferase active site
  • small subunit (SSU): mRNA binding
  • peptidyle transferase active site has three sub sites:
    • A (aminoacyl tRNA) site: where tRNA with single amino acid binds
    • P (peptidyl tRNA) site: where tRNA with peptide chain attached binds
    • E (exit) site: where tRNA leaves after its peptide chain is transferred to the next tRNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is tranlation initiated by?

A

initiation factors (IF)

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

(eukaryotes) how do initiation factors initate translation?

A
  • eIF = eukaryotic initation factor
  • SSU binds to mRNA
  • eIF4 untangles mRNA
  • eIF3 dissociates LSU from SSU => expose active site
  • eIF1 blocks A site => prevents tRNA binding to A site
  • eIF2 binds to tRNAimet, guides it to P site, expending one GTP => releases IFs, allow LSU to bind
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does SSU recognise mRNA in eukaryotes?

A

binds to 5’ cap and finds the first AUG after that

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

How does SSU recognise mRNA in prokaryotes?

A

SSU recognise the combination of shine dalgarno sequence (SDS) and AUG

prokaryotic ribosomes have anti-SDS at 3’ end of SSU RNA, binds to SDS

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

why does bacteria have to couple start codon with SDS (shine dalgarno sequence)

A
  • initiating AUG is distinguished from other AUGs by SDS
    • prevent ribosome from mistakening internal methionine codon or out of phase codon as start codon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is tRNAimet

A
  • initatior tRNA that has amino acid methionine bound to its 3’ end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is tRNAi

A
  • initiator tRNA
  • tRNAi is different to tRNA involved in elongation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what amino acid is eukaryotic and archaic tRNAi charged with

A

methionine => tRNAimet

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

what amino acid is bacteiral tRNAi charged with

A

formylmethionine => tRNAifmet

17
Q

what happens to the starting methionine after translation

A

starting methionine is differnt to internal methionine, it is cut off after translation

18
Q

what enzymes charges tRNA with amino acid

A
  • aaRS = aminoacyl-tRNA synthetase
  • catalyses formation of ester bond between 3’ end of tRNA and amino acid
  • requires hydrolysis of ATP and produces a high energy bond between the tRNA and amino acid
  • energy used in protein synthesis to link amino acid to the growing polypeptide chain
19
Q

what is meant by the redundancy of the genetic code?

A
  • most amino acids are specified by more than one mRNA codon
  • one amino acid can attach to several differnt tRNAs
20
Q

what factors aids the elongation of translation?

A

elongation factors (EF)

21
Q

How does elongation factors aid elongation?

A
  1. EF1 binds to tRNAaminoacyl , brings it to A site, expends a GTP then detaches
  2. EF2 shunts ribosome along one codon and triggers LSU’s petidyl-transferase activity, expends a GTP:
    • peptide bond formation between peptide chain on P site tRNApeptidyl and the amino acid on A site tRNAaminoacyl => one more amino acid is added to the peptide chain
    • the tRNA that had peptidyl group bound to it leaves via E site
    • the tRNAaminoacyl becomes tRNApeptidyl, is moved into P site
22
Q

what is the equivalent of EF1 in bacteria?

A

EF-Tu

23
Q

what is the equivalent of EF2 in bacteria?

A

EF-G

24
Q

How does termination of translation occur?

A
  • stop codon recognised by release factor = tRNApetidyl hydrolase
  • hyrolyses petidyl group off tRNA
  • similar shape to tRNA => it’s a molecular mimic, allows it to bind to the same active site that tRNA binds to
  • peptide then leaves via a channel in LSU
25
Q

secondary structures in mRNA can affect translation, for example, SecIS (selenocysteine insertion sequence) can convert a stop to selenocysteine, describe how that works

A
  • SeIB bound to selenocysteine tRNA binds to SecIS, the binding to SecIS allows for SelB to guide selenocysteine tRNA to A site
  • selenocysteine tRNA recognises stop codon UGA
  • stop codon is converted into selenocystein instead of terminating translation
  • translation continues to next codon
26
Q

how do eukaryotes and archaea increase translational efficiency?

A
  • polyribosome array:
    • ​acts on eIF4 coiled mRNA
    • association of PABP (polyadenosine binding protein) and eIF4 allow ribosome to immediately start at 5’ end of mRNA after finishing at 3’ end
    • translates many copies of the mRNA
27
Q

what is the native state of protein?

A

correctly folded, lowest entropy, => favoured entropic state of protein

28
Q

what are energy minima in protein folding

A

when a protein is incorrectly folded, but correcting it needs energy

29
Q

what helps correct incorrectly folded proteins?

A

enzymes called protein chaperones

30
Q

how are unfoldable and unwanted proteins processed

A
  • ubiquitinated and degraded in proteasomes
31
Q

how does proteasome degrade proteins?

A
  • Regulatory subunit recognises ubiquitinated protein
  • Protein is de-ubiquitinated and unfolded
  • Proteolytic subunit degrades protein

Molecular biology (8 decks)

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