Post-transcription and Translation Regulation

Question 1

What are the 4 components of translation initiation?

Answer 1

1) Amino acyl tRNA
2) Ribosome large unit
3) mRNA
4) Ribosome small unit

Question 2

What translation factors mediate initiation in prokaryotes?

Answer 2

1) IF1
2) IF2
3) IF3

Question 3

What are the translation factors that mediate initiation in eukaryotes?

Answer 3

1) eIF1, eIF1A
2) eIF2, eIF2B
3) eIF3
4) eIF4A, eIF4B, eIF4E, eIF4G, eIF4H
5) eIF5, eIF5B

Question 4

What translation factors mediate elongation in prokaryotes?

Answer 4

1) EF-Tu
2) EF-Ts
3) EF-G

Question 5

What translation factors mediate elongation in eukaryotes?

Answer 5

1) eEF1alpha
2) eEF1betagamma
3) eEF2

Question 6

What translation factors mediate termination in prokaryotes?

Answer 6

1) RF-1
2) RF-2
3) RF-3

Question 7

What translation factors mediate termination in eukaryotes?

Answer 7

1) eRF1
2) eRF3

Question 8

What does translation initiation in eukaryotes require?

Answer 8

1) mRNA
2) amino-acyl tRNA (met)
3) ribosome
4) GTP
5) 12 protein IFs

Question 9

What is the process of translation initiation in eukaryotes?

Answer 9

1) Translocation of 40S ribosome initiation complex along mRNA - AUG identified
2) Release of TFs (translation factors)
3) 60S subunit joins 40S/tRNA complex
4) 80S ribosome-met tRNA initiation complex completed

Question 10

How is translation initiation regulated?

Answer 10

1) Agents - repressor proteins/micro RNAs
2) Action - specific mRNAs/global translational activity

Question 11

What happens to regulation when a repressor binding to 5’ untranslated sequences Ferritin (iron-storage protein) in translation initiation?

Answer 11

1) IRE - iron-response element in mRNA 5’ region
2) Adequate iron levels - normal translation proceeds
OR
1) Low iron levels - IRP binds to iron-response element (IRE), interferes with translation initiation
2) Translation halts

Question 12

What happens to regulation when a repressor binding to 3’ untranslated sequences in translation initiation?

Answer 12

1) Translational repressors bind to regulatory sequences in 3’ untranslated region (3’ UTR) of mRNA
2) Inhibits translation by binding to eIF4E bound to 5’ MeG cap
3) Blocks formation of normal translation initiation complex

Question 13

How is translation initiated by non-coding RNA (microRNA)?

Answer 13

1) Target 60% of gene transcripts - 40% located on introns
2) Long non-coding RNAs (>200 nucleotides) can form complexes with chromatin to modify structure and recruit other transcription-modifying factors