APBio Unit 6 Mutations

Substiution Mutation

A type of point mutation where original nucleotide is replaced by a different nucleotide. Three types - Silent, missense, nonsense. Each affect amino acid sequence and protein structure differently.

Silent substitution mutation

Change in a single nucleotide that doesn’t result in a change in amino acid sequence. No effect on protein structure or function, no change in phenotype.

Missense Mutation

Change in a single nucleotide that results in a change in a single amino acid in the sequence. Variable effect on protein function and phenotype of the organism.

Nonsense Mutation

A change in a single nucleotide that results in a premature stop-codon in the mRNA sequence. Negative impact on protein structure and function, with codons after stop codon not being translated & protein not having all of its amino acids(So won’t fold or function properly)

Frameshift Mutation

A type of mutation where addition or removal of a single nucleotide changes the reading frame of the codons in mRNA, potentially altering the entire amino acid sequence downstream. This can lead to significant changes in protein structure and function. Always has negative effect on protein structure & organismal phenotype.

Insertion Mutation

Insertion of a single nucleotide into DNA sequence, with insertions changing reading frame(which also changes entire amino acid sequence afterwards.)

Effect: Protein will not fold or function correctly

Deletion Mutation

Deletion of a single nucleotide into the DNA sequence, changes the reading frame as well changing whole amino acid sequence.

Effect: Protein will not fold or function correctly