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Types of mutations

Types of mutations . Mutations are changes in the genetic material There are two basic types of mutations: Gene mutations - mutations that produce changes in a single gene Chromosomal mutations - mutations that produce changes in whole chromosomes. Gene mutations . Point mutations:

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Types of mutations

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  1. Types of mutations • Mutations are changes in the genetic material • There are two basic types of mutations: • Gene mutations - mutations that produce changes in a single gene • Chromosomal mutations - mutations that produce changes in whole chromosomes

  2. Gene mutations • Point mutations: • Involves changes in one or a few nucleotides (they occur at a single point in the DNA sequence) • They can be: • Substitutions • Insertions • Deletions

  3. Substitutions • One base is changed to another • Substitutions usually only affect a single amino acid

  4. Insertions and Deletions • A base is either inserted or removed from the DNA sequence • If a nucleotide is added or deleted, the bases are still read in groups of three, so every codon after is changed • These types of mutations cause Frameshift mutations • Can cause major changes to the protein, to the point where it can’t perform its normal function

  5. Chromosomal mutations • Involve the chromosomal changes in the number or structure of chromosomes • Can change the locations of genes on chromosomes, and the number of copies of some genes • Four types: • Deletions • Duplications • Inversions • Translocations

  6. Duplications and Deletion • Duplication (Nondisjunction): • The failure of a chromosome to separate from its homologue during meiosis • One gamete receives an extra copy of a chromosome and the other lacks it • Deletion: • Loss of a piece of a chromosome

  7. Translocations and Inversions • Translocation: • When a chromosome piece breaks off and reattaches to another, nonhomologous chromosome • Inversion: • Chromosome segment breaks off and then reattaches in reverse orientation to the same chromosome

  8. Significance of Mutations • Most mutations are neutral (they have little or no effect) • Mutations that cause dramatic changes in protein structure or gene activity can be very harmful • Mutations are a source of genetic variability in a species • Polyploidy- a mutation where an organism has an extra set of chromosomes • Polyploid plants are often larger and stronger

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