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Considering the DNA responsible for the haemoglobins, it is reasonable to conclude that A - VCE - SSCE Biology - Question 14 - 2003 - Paper 1
Question 14
Considering the DNA responsible for the haemoglobins, it is reasonable to conclude that A. haemoglobin S could be the result of a single base mutation in the DNA of ... show full transcript
Worked Solution & Example Answer:Considering the DNA responsible for the haemoglobins, it is reasonable to conclude that A - VCE - SSCE Biology - Question 14 - 2003 - Paper 1
Step 1
A. haemoglobin S could be the result of a single base mutation in the DNA of adult haemoglobin.
Answer
This statement is true. Hemoglobin S results from a point mutation, where a single nucleotide substitution occurs in the beta-globin gene, leading to a change in one amino acid in the hemoglobin structure.
Step 2
B. deletion of nucleotide 12 would change the fourth amino acid in the sequence of adult haemoglobin.
Answer
This statement is false. Deleting nucleotide 12 would lead to a frameshift mutation, altering the entire sequence of amino acids from that point onward. However, the fourth amino acid would be specifically affected depending on the original sequence, making it uncertain.
Step 3
C. a change in the 4th base of the DNA sequence would produce no change in either of the two haemoglobins.
Answer
This statement can be considered generally true, depending on the specific codons involved. If the 4th base does not alter the amino acid produced (due to redundancy in the genetic code), then neither hemoglobin would be affected.
Step 4
D. in haemoglobin S, a change in the 10th base of the DNA sequence would produce no change in the amino acid sequence.
Answer
This statement is generally true; if the change does not affect a critical position in the coding sequence that leads to a different amino acid, then it may have no effect on the amino acid sequence.