AP BIOLOGY

Detailed explanation-1: -Base substitutions are the simplest type of gene-level mutation, and they involve the swapping of one nucleotide for another during DNA replication.

Detailed explanation-2: -Substitution, as related to genomics, is a type of mutation in which one nucleotide is replaced by a different nucleotide. The term can also refer to the replacement of one amino acid in a protein with a different amino acid. National Human Genome Research Institute.

Detailed explanation-3: -Base Substitutions Single base substitutions are called point mutations, recall the point mutation Glu—–> Val which causes sickle-cell disease.

Detailed explanation-4: -Substitution mutations can be good, bad, or have no effect. They cause three specific types of point mutation: silent, missense, and nonsense mutations. A silent mutation is one where the function of the protein is not changed. A missense mutation codes for the wrong protein.

Detailed explanation-5: -Missense: A missense variant is a type of substitution in which the nucleotide change results in the replacement of one protein building block (amino acid) with another in the protein made from the gene.