Mutation

DNA sequencing- the process of determining the base sequence of DNA

Mutation- changes in the base sequence of the DNA 

• Can be positive, negative or no effect

• Can be large scale or small scale (at the nucleotide level to the chromosomal level)

• May be spontaneous or induced by a mutagen

Small Scale Mutation

• Substitution mutation- replacing one or more nucleotide

  • Silent- same amino acid is produced

  • Nonsense- premature stop codon 

  • Missense- a new amino acid is produced

    • Conservative- new amino acid, same chemical property

    • Nonconservative- different chemical property

• Frameshift- the reading frame is shifted due to insertion or deletion of nucleotide paris

Large Scale Mutation

• Mutation at the chromosomal level

  • Nondisjunction- chromosomes do not separate properly during meiosis which causes aneuploidy

    • Aneuploidy- incorrect number of chromosomes

  • Deletion- a segment on the chromosome is deleted

  • Duplication- a segment is repeated

  • Inversion- a segment is reversed

  • Translocation- a segment is moved to a nonhomologous chromosome (if the promoter is moved with it, it can still be expressed)