Mutations are changes in the DNA that can result in no protein or an altered protein being synthesized
Single gene mutations:
Substitution: the replacement of one base, involving the alteration of a DNA nucleotide
Insertion: the addition of one base sequence as a result of substitution
Deletion: the removal of one base
Substitution mutations, Insertion, and Deletion Mutations
Effects of mutations on DNA sequence:
CGAcc6AcT -> CGAccGAC: one base added, one base change
L -> LL: one base change
CGAccGAA -> TCGACCC: three effects:
Missense: one amino acid is changed for another
Nonsense: premature stop codon, resulting in frame-shift mutations
Splice-site: introns may be retained or exons removed, causing a major effect on protein structure
Chromosome Structure Mutations:
Translocation: non-homologous chromosomes alter the number or structure of chromosomes
Inversion: homologous chromosomes reverse their structure
Duplication: homologous chromosomes have a section added
Deletion: homologous chromosomes have a section removed
Substantial changes in chromosome structure are often lethal
Deletion: a section of a chromosome is removed
Duplication: a section of a chromosome is added
Inversion: a section of a chromosome is reversed
Translocation: a section of a chromosome is added to a non-homologous chromosome, affecting genes like clotting factors and causing disorders like Haemophilia A or Cri-du-chat syndrome