Biology · D Continuity and change. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
A gene mutation is a change in the base sequence of a gene. In a substitution, one base is replaced by another and the length stays the same. In an insertion a base is added, and in a deletion a base is removed.
A substitution changes only one codon. Because the code is degenerate, the new codon may still code for the same amino acid. An insertion or deletion of one or two bases causes a frameshift: every codon after it is read differently, so the polypeptide usually does not work.
Mutations happen at random. They are not directed by what the organism needs. Only mutations in germ cells can be inherited.
Students say that any substitution changes the protein. Check the codon first: if the new codon codes for the same amino acid, the polypeptide is unchanged.
Answer: A much shorter polypeptide of 49 amino acids, which will almost certainly not function.
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