Genetic Mutations Detailed Notes

Genetic Mutations

Types of Gene Mutations

  • Normal DNA Sequence:TAT CAT CCT AAG GTA
    • Amino Acids: Tyr His Pro Lys Val
Examples of Mutations:

  • Substitution Mutation:

    • Changed Sequence:
      TAT CAT CGT AAG GTA
    • Amino Acids: Tyr His Arg Lys Val

  • Insertion Mutation:

    • Changed Sequence:
      TAT CAT CGC TAA GGT A
    • Amino Acids: Tyr His Arg Stop Gly

  • Deletion Mutation:

    • Changed Sequence:
      TAT C_C CTA AGG TA
    • Amino Acids: Tyr Leu Leu Arg

Mutations and Their Effects on Proteins

  • General Info:

    • Mutations occur during DNA replication.

  • Classification:

    • Point Mutations:
    • Definition: One nucleotide is replaced by another.
    • Frameshift Mutations:
    • Definition: Insertion or deletion of a nucleotide changes the reading frame.

Point Mutations

  • Types of Point Mutations:

    • Silent Mutation: No change in protein.
    • Nonsense Mutation: Leads to a premature stop codon.
    • Missense Mutation: A different amino acid is produced.
    • Subtypes:
      • Conservative: Similar properties of amino acids.
      • Non-conservative: Different properties of amino acids.

  • Examples:

    • DNA Level:
    • TTC vs TTT
    • mRNA Level:
    • AAG vs AAA
    • Protein Level:
    • Lys vs Lys

Frameshift Mutations

  • Normal Sequence:

    • e.g. ATG CAT TGC

  • Example of Insertion:

    • Original Sequence: ATTGCATTGC
    • Change: Reading frame altered due to insertion.

Chromosome Structure Changes

  • Types of Changes:
    • Deletion: Segment of a chromosome breaks off.
    • Duplication: A segment occurs more than once.
    • Inversion: A segment is reversed 180 degrees.
    • Translocation: A segment moves to a non-homologous chromosome.

Examples:

  1. Deletion:

    • Original: A B C D E F G H
    • After Deletion: A B C E F G H

  2. Duplication:

    • Original: A B C D E F G H
    • After Duplication: A B C B C D E F G H

  3. Inversion:

    • Original: A B C D E F G H
    • After Inversion: A D C B E F G H

  4. Translocation:

    • Original: A B C D E F G H
    • After Translocation:
      A B P Q R
      M N O