What type of mutation can alter dna by the addition of a nucleotide base?
a.)crossing-over
b.)deletion
c.)insertion
d.)base-pair substitution

insertion

Crossing over is when homologous* chromosomes exchange genes, resulting in gene combinations.

Deletion is when a base pair is deleted from DNA. Insertion is when a base pair is added to DNA. Both insertion and deletion are serious because every amino acid beginning at the mutation will most likely be incorrect. This will lead to a nonfunctional protein.

Base-pair substitution is a substitution of one base pair for another in DNA. The effects of this may be a silent** point, missense*** point, or nonsense point.

*A pair of matching chromosomes. They have the same genes but can have different versions.

**A special case where no amino acids are affected.

***Affects one animo acid. The whole protein structure and function may or may not be disrupted.

Results in a stop codon that shortens the protein.