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Below is the DNA sequence from the beginning of a gene coding for an enzyme involved in photosynthesis - VCE - SSCE Biology - Question 4 - 2004 - Paper 1
Question 4
Below is the DNA sequence from the beginning of a gene coding for an enzyme involved in photosynthesis. The upper line of bases (in bold) represents the template str... show full transcript
Worked Solution & Example Answer:Below is the DNA sequence from the beginning of a gene coding for an enzyme involved in photosynthesis - VCE - SSCE Biology - Question 4 - 2004 - Paper 1
Step 1
Write the mRNA sequence that would be transcribed from this DNA sequence.
Answer
To transcribe the mRNA sequence from the given DNA template strand, recall that adenine (A) pairs with uracil (U) in RNA, thymine (T) pairs with adenine (A), guanine (G) pairs with cytosine (C), and cytosine (C) pairs with guanine (G). Therefore, the transcribed mRNA sequence will be:
[ 5' ext{AUGAAUUCGCUGC} 3' ]
Step 2
Step 3
Explain the effect this mutation will have on the amino acid sequence of the protein produced.
Answer
The mutation will result in a different amino acid in the sequence. Specifically, if the original base led to an asparagine (Asn) amino acid, substituting it with C could replace it with lysine (Lys). This change may alter the protein's function depending on the role of the altered amino acid in the protein structure or activity.
Step 4
The 11th base pair of the sequence is deleted. Explain the effect that this mutation will have on the amino acid sequence of the protein produced.
Answer
The deletion of a base pair alters the reading frame of the mRNA, potentially leading to a frameshift mutation. This means that all downstream amino acids may be different than originally coded, and it may introduce a premature stop codon, resulting in a truncated protein that is likely nonfunctional.