Chapter 15.6: The Structure of tRNA and Ribosomes

Question 1

Define o Aminoacyl-tRNA Synthetases

Answer 1

any of a group of enzymes that attach specific amino acids to the correct tRNA during the tRNA-charging reaction. Each of the 20 amino acids has a corresponding enzyme

Question 2

What is any of a group of enzymes that attach specific amino acids to the correct tRNA during the tRNA-charging reaction. Each of the 20 amino acids has a corresponding enzyme?

Answer 2

o Aminoacyl-tRNA Synthetases

Question 3

What are the two parts of tRNA molecule?

Answer 3

acceptor stem and anticodon loop

Question 4

Define acceptor stem

Answer 4

the 3’ end of a tRNA molecule; the portion that amino acids become attached to during the tRNA charging reaction

Question 5

What is the 3’ end of a tRNA molecule; the portion that amino acids become attached to during the tRNA charging reaction?

Answer 5

acceptor stem

Question 6

What is the function of the anticodon loop?

Answer 6

o Bottom loop of the cloverleaf, and it can base-pair with codons in mRNA

Question 7

Define charging reaction

Answer 7

the reaction by which an aminoacyl-tRNA synthetase attaches a specific amino acid to the correct tRNA using energy from ATP

Question 8

What is the reaction by which an aminoacyl-tRNA synthetase attaches a specific amino acid to the correct tRNA using energy from ATP?

Answer 8

charging reaction

Question 9

Is the charging reaction endergonic or exergonic?

Answer 9

endergonic

Question 10

What is the first step of the charging reaction?

Answer 10

In the first step of the reaction, the amino acid is activated. The amino acids react with ATP to produce an intermediate with the carboxyl end of the amino acid attached to AMP. The two terminal phosphates (pyrophosphates) are cleaved from ATP in this reaction.

Question 11

After In the first step of the reaction, the amino acid is activated. The amino acids react with ATP to produce an intermediate with the carboxyl end of the amino acid attached to AMP. The two terminal phosphates (pyrophosphates) are cleaved from ATP in this reaction, what is the next step of the charging reaction?

Answer 11

The amino acid-AMP complex remains bound to the enzyme. The tRNA next binds to the enzyme.

Question 12

After The amino acid-AMP complex remains bound to the enzyme. The tRNA next binds to the enzyme., what is the last step of the charging reaction?

Answer 12

The last step of the reaction transfers the amino acid from AMP to the tRNA, producing a charged tRNA and AMP. The charged tRNA consists of a specific amino acid attached to the 3’ acceptor stem of the its RNA

Question 13

Define P site

Answer 13

in a ribosome, the peptidyl site that binds to the tRNA attached to the growing polypeptide chain

Question 14

What is in a ribosome, the peptidyl site that binds to the tRNA attached to the growing polypeptide chain?

Answer 14

P site

Question 15

Define A site

Answer 15

in a ribosome, the aminoacyl site, which binds to the tRNA carrying the next amino acid to be added to a polypeptide chain

Question 16

What is in a ribosome, the aminoacyl site, which binds to the tRNA carrying the next amino acid to be added to a polypeptide chain?

Answer 16

A site

Question 17

Define E site

Answer 17

in a ribosome, the exit site that binds to the tRNA that carried the previous amino acid added to the polypeptide chain

Question 18

How are the sites in ribosomes organized?

Answer 18

o Relative to the mRNA, the sites are arranged 5’ to 3’ in the order E, P, and A

Question 19

What is the order that tRNA goes through the ribosome?

Answer 19

o The incoming charged tRNAs enter the ribosome at the A site, transit through the P site, and then leave via the E site

Question 20

What are the two functions of the ribosome?

Answer 20

o The two functions of the ribosome involve decoding the transcribed message and forming peptide bonds

Question 21

Define peptidyl transferase

Answer 21

in translation, the enzyme responsible for catalyzing the formation of a peptide bond between each new amino acid and the previous amino acid in a growing polypeptide chain

Question 22

What is in translation, the enzyme responsible for catalyzing the formation of a peptide bond between each new amino acid and the previous amino acid in a growing polypeptide chain?

Answer 22

peptidyl transferase