Ribosomes and Protein Synthesis

Question 1

What is the CCA site in tRNA?

Answer 1

site where the amino acid attaches to the tRNA

Question 2

which two amino acids only have one codon?

Answer 2

methionine and tryptophan

Question 3

sickle cell anemia caused by?

Answer 3

glutamatic acid to valine

Question 4

what does aminoacyl tRNA synthetase do? What special thing does it have?

Answer 4

couples a specific amino acid to its tRNA. Has editing abillity

Question 5

How many rRNAs make up a eukaryotic ribosome? prokaryotic ribosome?

Answer 5

4 for eukaryotic, 3 for prokaryotic

Question 6

subunits and major ribosome for eukaryotic and prokaryotic?

Answer 6

eukaryotic- 40S and 60S makes 80S

prokaryotic- 30S and 50S makes 70S

Question 7

Initiation of translation in eukaryotes: big picture major stuff, as well as the helicase activity. (2 big things total)

Answer 7

1. Ternary complex is made up of eIF2-GTP and tRNAi-Met.

2. eIF4a has the helicase activity, which unwinds the mRNA when the start codon is found

Question 8

chain elongation in eukaryotes: All 4 steps

Answer 8

1. a ternary complex containing eF1-GTP and second amino acid bind to A site.
2. GTP is hydrolyzed, and a peptide bond is formed between Met and the new amino acid
3. eF2-GTP is hydrolyzed, which displaces the original tRNA for the Met to the E site, and the tRNA for the new amino acid to the P site.
4. tRNA in the E site is ejected when the new eF1-GTP is hydrolyzed

Question 9

Termination of translation in eukaryotes: All 3 steps

Answer 9

1. Stop codon is reached, and eRF1 enters A site with eRF3-GTP.
2. eRF3-GTP is hydrolyzed, and the peptide is cleaved form the tRNA in the P site, and E site tRNA is released. This is now called the post-termination complex
3. ABCE1 ATPase and initiation factors cause ribosome subunits to separate