DAT - Mutations

Base Substitutions

ONE Nucleotide is replaced by another; Can be silent, missense, or nonsense

Silent Mutations

Single nucleotide change does NOT change the encoded amino acid; Relies on wobble bases and codon degeneracy

Wobble Bases

The 3rd base in a codon (mutation here may leave the encoded amino acid unchanged)

Missense Mutations

Single nucleotide change changes the produced amino acid; In conservative missense, the mutated amino acid is similar in structure and function to the unmutated amino acid; In non-conservative missense, the mutated amino acid does not resemble the unmutated amino acid (more likely to significantly change the protein’s function)

Nonsense Mutations

Single nucleotide change results in a STOP codon; Causes early termination of translation and leads to a shortened protein product

Frameshift Mutations

Results in a shift to the reading frame, altering successive codons and how the mRNA is read; Insertions and deletions

Null Mutations

Loss-of-function mutation that produces a null allele (non-functioning); Usually the result of other mutations; Leads to loss of protein function

Duplication

Region of DNA is duplicated, chromosomal arm lengthens and results in atypical banding pattern

Transposons

DNA sequences that can move and integrate into different spots in the genome; “jumping genes”; Cause mutations

Mismatch Repair

Enzymes are used to check for nucleotide matches not caught during DNA replication

Nucleotide Excision Repair

Damaged DNA SEGMENTS are cut out and replaced with correct DNA using complementary base pairing; Seen with physical damage like UV radiation