gen-define-a-point-mutation-and-give-one-short-worked-example-b1e8

Define a point mutation and give one short worked example.

# Point Mutation **Definition:** A point mutation is a change in a single nucleotide base pair in a DNA sequence. It involves the substitution, insertion, or deletion of one nucleotide at a specific position in the genome. ## Worked Example **Type:** Substitution (most common point mutation) **Original DNA sequence:** ``` 3' - TAC - GCA - TTA - GGC - 5' (template strand) 5' - ATG - CGT - AAT - CCG - 3' (coding strand) ``` **mRNA transcribed:** ``` 5' - AUG - CGU - AAU - CCG - 3' ``` **Amino acids translated:** ``` Met - Arg - Asn - Pro ``` --- **Mutated DNA sequence** (C→T substitution at position 7): ``` 3' - TAC - GCA - TTA - GGT - 5' (template strand) ↑ mutation ``` **mRNA transcribed:** ``` 5' - AUG - CGU - AAU - CCA - 3' ↑ changed ``` **Amino acids translated:** ``` Met - Arg - Asn - Pro ``` **Result:** This is a **silent mutation** – the codon changed from CCG to CCA, but both code for proline, so the protein remains unchanged.