Mutations


‘Mutations’ in biology refers to change from the normal or expected gene. Not all mutations result in a change in phenotype. Of those that do changes can be beneficial, detrimental, or neither - many mutations do not affect an individuals ability to survive

Whether a mutation helps, hurts or does nothing depends on 2 factors:

  1. The organism’s environment

  2. The type/severity of the mutation

Part A: Whole Chromosome Mutation

1. Nondisjuction

  • Chromosomes fail to separate during meiosis

2nd meiotic division

*Note: The non-viable egg is a deletion

2. Deletion: A sperm or egg cell is missing an entire chromosome

  • Very severe - usually fatal


3. Translocation:

  • A piece of a non-homologous (different pair) chromosome is transferred to another chromosome

    • they get stuck together during meiosis


4. Insertion

  • A piece of one chromosome is inserted in a non-homologous chromosome

Nucleotide mutations:

(Zoomed in version, one change that could alter a huge phenotype)

  1. Point mutation - change in a nucleotide that (usually) changes only 1 amnio acid (Most common, having different options, genetically very diverse)

Substitutions

2. Frameshift mutation - Insertion or deletion of a single nucleotide that changes the way every amino acid after the mutation is read.