Question

During DNA replication, a mistake occurs in which a single letter is replaced with a different one. This is called a substitution mutation and can occur in many genetic diseases, such as sickle-cell anemia. Instead of the nitrogenous bases ATG, the DNA now codes for ATA.

Part 1: Identify the sequence of complementary mRNA nucleotides for the original DNA, ATG, and the mutated DNA, ATA.

Part 2: Use the codon table above to determine if this mutation in the DNA code will cause a change in the amino acid. Explain your reasoning.

Answer 1

Part 1:

1. **Original DNA sequence (ATG)**:

- Complementary mRNA sequence:

- Original DNA: ATG

- mRNA: UAC

2. **Mutated DNA sequence (ATA)**:

- Complementary mRNA sequence:

- Mutated DNA: ATA

- mRNA: UAU

Part 2:

3. **Determining Amino Acid Change**:

- Using the codon table, we find that:

- Original DNA (ATG) codes for the amino acid Methionine (Met).

- Mutated DNA (ATA) codes for the amino acid Isoleucine (Ile).

4. **Explanation**:

- The mutation from ATG to ATA results in a change from Methionine to Isoleucine.

- This substitution mutation alters the amino acid coded for by the DNA sequence, which can potentially affect the structure and function of the protein produced.

- Changes in amino acids can lead to different protein structures and functions, impacting the overall health and functionality of an organism.