It is reasonable to conclude that during transcription of normal haemoglobin, the mRNA codon sequence could be:
A - VCE - SSCE Biology - Question 13 - 2003 - Paper 1
Question 13
It is reasonable to conclude that during transcription of normal haemoglobin, the mRNA codon sequence could be:
A. GTT for amino acid 1
B. CTT for amino acid 2 ... show full transcript
Worked Solution & Example Answer:It is reasonable to conclude that during transcription of normal haemoglobin, the mRNA codon sequence could be:
A - VCE - SSCE Biology - Question 13 - 2003 - Paper 1
Step 1
A. GTT for amino acid 1
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The DNA triplet for amino acid 1 (valine) is CAA or CAG, which transcribes to GTT or GTC in mRNA. Thus, this statement is correct.
Step 2
B. CTT for amino acid 2
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The second amino acid is histidine, which can be encoded by DNA triplets CAT or CAC. The corresponding mRNA codons would be GUA or GUC; hence, this statement is incorrect.
Step 3
C. AAT for amino acid 3
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The third amino acid (leucine) can be encoded by AAT, which doesn't apply. Leucine is encoded by AAA or AAG. Therefore, this is incorrect.
Step 4
D. GGA for amino acid 4
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The fourth amino acid (proline) can indeed be encoded by GGA. This matches the triplet for proline, hence this is correct.
