Comparing Eukaryotic and Prokaryotic Translation

Question 1

In what stage of translation is there a significant difference between eukaryotes and prokaryotes?

Answer 1

Initiation

Question 2

How does translation initiation differ between prokaryotes and eukaryotes?

Answer 2

Prokaryotic mRNA is available for ribosomes during transcription.
Eukaryotic mRNA needs to get process/transported out of the nucleus

Question 3

What is an eIF?

Answer 3

eukaryotic initiation factor

Question 4

Outline the general steps of eukaryotic translation initiation.

Answer 4

1. eIF4G and eIF4E bind to 5’ cap of mature mRNA and CBP dissociates
2. eIF2 helps initiator tRNA bind to P-site of 40S subunit and forms 43S initiation complex
3. 43S initiation complex binds to 5’ end of mRNA
4. 43S initiation complex binds to start codon and eIFs dissociate
5. 60S subunit assembles and completes 80S ribosome

Question 5

What is the Kozak consensus sequence in eukaryotic translation initiation?

Answer 5

CCpurineCCAUGG

Question 6

What is the difference between prokaryotic initator tRNA and eukaryotic initiator tRNA?

Answer 6

P: charged with N-formylmethionine
E: charged with methionine

Question 7

How do prokaryotes and eukaryotes differ in the ways in which their small subunit bind to mRNA?

Answer 7

P: bind directly onto RBS in middle of mRNA
E: Binds to 5’ end of mRNA and then scans for Kozak sequence

Question 8

Why are eukaryotic genes monocistronic?

Answer 8

Prokaryotes can have polycistronic genes since their ribosomes can bind directly onto the middle of mRNA.
Eukaryotes scan mRNA from 5’ end and starts translation at the first Kozac sequence encountered

Question 9

What are post-translational modifications of proteins?

Answer 9

Cleavage of initiator Met
Cleavage of signal sequences
Addition of cofactors
Glycoylation, acteylation, phosphorylation

Question 10

What is the aminoacyl-tRNA carrier in prokaryotes and eukaryotes?

Answer 10

P: EF-Tu
E: eEF-1A

Question 11

What protein is used for the translocation power stroke in prokaryotes vs. eukaryotes?

Answer 11

P: EF-G
E; eEF-2

Question 12

What is the elongation factor recycled in eukaryotic vs. prokaryotic translation?

Answer 12

P: EF-Ts
E: eEF-1B

Question 13

What proteins are used for UAA and UAG recognition in prokaryotes vs eukaryotes?

Answer 13

P: RF-1
E: eRF

Question 14

What proteins are used for UGA and UAA recognition in prokaryotes vs eukaryotes?

Answer 14

P: RF-2
E: eRF

Question 15

What proteins are used for GTP binding in prokaryotic vs eukaryotic translation termination?

Answer 15

P: RF-3
E: eRF