Final answer:
A point mutation affects a single base in a DNA sequence and can lead to changes in base pairing during replication, potentially altering protein function. Types include silent, missense, and nonsense mutations, and their impact can range from negligible to severe, influencing organismal traits and health.
Step-by-step explanation:
A point mutation occurs when a single base in a DNA sequence is altered, which can happen through substitutions of one base for another, such as replacing cytosine (C) with adenine (A).
This change will affect how the strand pairs with its complementary strand in DNA replication. For example, if a C that normally pairs with a G is replaced by an A, in replication A will pair with a T instead, leading to a permanent change in the DNA sequence of the replicated strand.
There are three main types of point mutations: silent mutations, which do not alter the amino acid sequence of proteins; missense mutations, which change one amino acid for another and can have varying effects.
Depending on the role and location of the amino acid in the protein; and nonsense mutations, which create a premature stop codon, often resulting in nonfunctional proteins.
When a deletion occurs in a DNA strand, removing one or more bases, it can also be classified as a point mutation if only a single base pair is affected.
This kind of mutation can lead to a frameshift, significantly altering the triplet reading frame and, thus, the entire sequence of amino acids encoded by the gene.
The effects on the organism can be severe, potentially altering protein function or leading to the production of entirely nonfunctional proteins.