Chapter 39 - The Genetic Code

Question 1

Degenerate

Answer 1

Redundancy.

Question 2

tRNA

Answer 2

The 3-dimensional structure of the molecule is L-shaped. Contains unusual bases, such as inosine, or bases that have been modified. 10% of bases are unusual. Amino acids get attached to a hydroxyl group of adenosine in the 3’ CCA region of the acceptor stem. The 5’ terminal residue is usually a phosphorylated pG. The anticodon is in a loop near the center of the sequence.

Question 3

Wobble Effect

Answer 3

Recognition of the third base in the codon by the anticodon is sometimes less discriminating.

Question 4

Aminoacyl-tRNA Synthetase

Answer 4

Catalyzes the activation of amino acids. The first step is the formation of aminoacyl adenylate or aminoacyl-AMP. The aminoacyl group is then transferred to a specific tRNA recognized by the synthetase. The aminoacyl-AMP never leaves the active site of the synthetase.

Question 5

Synthetases

Answer 5

True translators of the genetic code.

Question 6

Ribosome

Answer 6

2 subunits with proteins (1/3 mass) and RNA (2/3 mass).

Question 7

The 50S Subunit

Answer 7

34 proteins, 23S RNA, and 5S RNA.

Question 8

The 30S Subunit

Answer 8

21 proteins and 16S RNA.

Question 9

70S Ribosome

Answer 9

30S subunit plus 50S subunit. In prokaryotic cells only.

Question 10

80S Ribosome

Answer 10

40S subunit plus 60S subunit. In eukaryotic cells only.