Question

Practice Problem 50 A tRNA anticodon is 5' GAA 3'. Answer the following questions.

Part A Which one of the following codons is recognized by this tRNA? Which one of the following codons is recognized by this tRNA?   5' UUC 3'   5' CTT 3'   5' CUU 3'   5' TTC 3' Part B The first base at the 5' end of the anticodon has relaxed base-pairing rules allowing some tRNAs to bind multiple codon sequences. This is called the third base "wobble" hypothesis. How many codons could a tRNA with the anticodon 5'-GAA-3' recognize? Enter your answer as a whole number. Part C Which amino acid does this tRNA carry?   Glutamic Acid   Phenylalanine   Lysine   Leucine

Answer 1

Part A = 5' UUC 3'
Part B = 5' UUC 3' and 5' UUU 3'
Part C = Phenylalanine
2. Part A = UGU and GUG

Given tRNA anticodon = 5' GAA 3'

Then,
Part- A,
codon = complimentary of anticodon
i.e for G = C
A = U
   and, it will be as anticodon 5' G A A 3'
codon 3' C U U 5'
Therefore,
codon will be = 5' UUC 3'

Part- B
Actually,
5' GAA 3' should only Recognize 5' UUC 3'
But as per Wobble Hypothesis
the Base 1 in Anticodon can form non-Watson-Crick base pairing with the 3rd position of the Codon
i.e
G can base pair with C and U (as per Wobble pairing Rules)
Therefore, we will get
for anticodon 5' GAA 3'
codons will be = 5' UUC 3' and 5' UUU 3'

Part-C

UUC and UUU codes for = Phenylalanine