Rodgers 4-23 Ribosome

Question 1

Which subunit contains the EPA sites

Answer 1

the large subunit- 50S bacteria 60S eukar.

Question 2

Which subunit receives the mRNA

Answer 2

the small subunit- 30S bacteria 40S eukaryotes

Question 3

What is the tertiary structure that dominates rRNA

Answer 3

coaxial helices: where bases stack between different backbones of A-DNAhelix. Bases shift out toward minor groove

Question 4

2 different RNA interactions in minor groove

Answer 4

both make coaxial helices: ribose zippers (mediated by 2’OH), “A-minor” interaction between adenines of 2 minor grooves

Question 5

differences between bac and euk ribosomes

Answer 5

outer protein/RNA shell larger in eukaryotes

Question 6

how do ribosomal interactions differ in euk and prok?

Answer 6

only elongation is similar process - mediation with different factors because of exterior differences

Question 7

What action allows translocation of the ribosome

Answer 7

binding of the tRNA to the A site, a conformation chnge that it transmitted to the P site- catalyzed by both tRNA, rRNA

Question 8

What external factor is needed for elongation beyond the tRNA rRNA

Answer 8

GTP-hydrolyzing elongation factor

Question 9

Which atoms participate in the growing peptide interaction

Answer 9

The n-terminal of A-site tRNA attacks the aminoacyl connection to the P-site tRNA

Question 10

How is protein synthesis terminated

Answer 10

release factors recognizes when stop codon bound at A-site, hydrolysis of tRNA at P site, recruits another GTP factor to site, subunit dissociation

Question 11

How do growing peptides fold

Answer 11

co-translational folding: secondary structures develop in tunnel of ribosome, chaperone associate with exit region of ribosome. SPEED of translation affects FOLDING