protein synthesis: eukaryotes vs prokaryotes

Question 1

what are the 5 differences between eukaryotic & prokaryotic protein synthesis?

Answer 1

1. location of transcription & translation
2. sequence of occurrence of transcription & translation
3. initiation of transcription
4. termination of transcription
5. post-transcriptional modification

Question 2

what is the difference in location of transcription & translation between prokaryotic protein synthesis & eukaryotic protein synthesis?

Answer 2

• in prokaryotic protein synthesis, both transcription & translation occur in the cytoplasm, as prokaryotes do not have a nucleus
• however, in eukaryotic protein synthesis, transcription occurs in the nucleus while translation occurs in the cytoplasm

Question 3

what is the difference in the sequence of occurrence of transcription & translation between prokaryotic & eukaryotic protein synthesis?

Answer 3

• in prokaryotic protein synthesis, both transcription & translation occurs simultaneously
• in eukaryotic protein synthesis, transcription occurs before translation

Question 4

what is the difference in transcription initiation between prokaryotic & eukaryotic protein synthesis?

Answer 4

• in prokaryotic protein synthesis, transcription factors are not involved, and no transcription initiation complex is formed, as the sigma factor of prokaryotic RNA polymerase recognises & binds to the promoter
• whereas in eukaryotic protein synthesis, transcription factors are involved in the formation of the transcription initiation complex

Question 5

what is the 1st difference in transcription termination between prokaryotic & eukaryotic protein synthesis?

Answer 5

• in prokaryotic protein synthesis, transcription termination involves transcribing a terminator sequence which serves as the termination signal
• however, in eukaryotic protein synthesis, transcription termination involves transcribing a terminator sequence, but utilises a transcribed sequence in the pre-mRNA (polyadenylation signal) as the termination signal

Question 6

what is the 2nd difference in transcription termination between prokaryotic & eukaryotic protein synthesis?

Answer 6

• in prokaryotic protein synthesis, formation of a hairpin loop in the mRNA is required for release from the DNA template
• while in eukaryotic protein synthesis, proteins will bind to 10-35 nucleotides past the polyadenylation signal & cut the pre-mRNA for release from the DNA template

Question 7

what is the difference in post-transcriptional modification between prokaryotic & eukaryotic protein synthesis?

Answer 7

• in prokaryotic protein synthesis, post-transcriptional modification does not occur
• in eukaryotic protein synthesis, post-transcription modification occurs after transcription, but before translation, where the pre-mRNA is processed to form mature mRNA