The following is a segment of the template strand of human BRCA1 gene:
TGG AAT TAT CTG CTC TTC GCG
c. If there is a point mutation in the fourth nucleotide triplet and A replaces G, what is the change, if any, in the amino acid sequence?

Verified step by step guidance

1. Identify the original nucleotide sequence of the template strand: TGG AAT TAT CTG CTC TTC GCG.
2. Determine the corresponding mRNA sequence by transcribing the template strand. Use the base-pairing rules: A pairs with U, T pairs with A, G pairs with C, and C pairs with G.
3. Divide the mRNA sequence into codons (groups of three nucleotides) starting from the 5' end.
4. Locate the fourth codon in the mRNA sequence and determine the original amino acid it codes for using a codon table.
5. Apply the point mutation (A replaces G in the fourth codon of the template strand), transcribe the new mRNA sequence, and determine the new amino acid sequence. Compare the original and mutated amino acid sequences to identify any changes.

Key Concepts

DNA Structure and Function

DNA is composed of nucleotide sequences that encode genetic information. Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base. The sequence of these bases determines the genetic code, which is translated into proteins. Understanding the structure of DNA is essential for analyzing mutations and their potential effects on protein synthesis.

Point Mutation

A point mutation is a change in a single nucleotide in the DNA sequence. This can result in a different amino acid being incorporated into a protein during translation, potentially altering its function. Point mutations can be classified as silent, missense, or nonsense mutations, depending on their effect on the resulting protein. Identifying the type of mutation is crucial for predicting its impact on the organism.

Amino Acid Codons

Amino acids are encoded by triplet codons in mRNA, which are derived from the DNA template strand. Each codon corresponds to a specific amino acid or a stop signal during protein synthesis. Understanding the genetic code is vital for determining how mutations affect the amino acid sequence of proteins. In this case, analyzing the codon change due to the point mutation will reveal the impact on the protein structure.