tRNA and Protein Synthesis

Question 1

tRNA (5)

Answer 1

• smallest RNA type (75-85 nt)
• takes an amino acid to the right location
• 50 different tRNAs
• 20 RNA families
• each family has a different type of aminoacylsynthatase (AAST)

Question 2

Amino acids (2)

Answer 2

• bind together to form peptides
• 20 different amino acids

Question 3

Aminoacylsynthatase (2)

Answer 3

• ensures the correct tRNA and correct amino acid bind
• 2 active sites = less chance for mistakes

Question 4

First active site of AAST:

Answer 4

Takes the amino acid and energizes it with ATP -> aa-AMP + Phosphate

Question 5

Second active site of AAST:

Answer 5

Takes aa-AMP and bind it to the tRNA -> aa-tRNA + AMP

Question 6

tRNA has 3 different loops:

Answer 6

Left: D-loop
Bottom: Variable loop
Right: TYC-loop

Question 7

The D-loop and TYC loop…

Answer 7

both have modified nucleotides.

Question 8

The variable loop…

Answer 8

identifies the tRNA for binding with a anti-codon.

Question 9

Nucleotides on the 3’ strand:

Answer 9

CCA

Question 10

Protein Synthesis Steps

Answer 10

1. Initiation
2. Elongation
3. Termination

Question 11

Step #1 (Steps 1-5 of Initiation)

Answer 11

40S RNA will leave the granular region of the nucleolus to the cytoplasm

Question 12

Step #2 (Steps 1-5 of Initiation)

Answer 12

IF3 protein will attach the mRNA to the 40S

Question 13

Step #3 (Steps 1-5 of Initiation)

Answer 13

The 1st codon will code for methione (AUG)

Question 14

Step #4 (Steps 1-5 of Initiation)

Answer 14

IF1 and IF2 bind to the tRNA to facilitate binding to the 40S

Question 15

Step #5 (Steps 1-5 of Initiation)

Answer 15

The 60S subunit binds and the IF1, IF2, and IF3, will detach.

Question 16

IF2 regulation:

Answer 16

Can go through phosphorylation to “turn off”