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GENETIC MUTATIONS

GENETIC MUTATIONS. Sexual Reproduction. Results in variations Variations help organisms adapt Allow breeders to develop new strains of plants/animals Most variations come from segregation and crossing over in meiosis. Source of Variations. Most variations come from: Segregation

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GENETIC MUTATIONS

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  1. GENETIC MUTATIONS

  2. Sexual Reproduction • Results in variations • Variations help organisms adapt • Allow breeders to develop new strains of plants/animals • Most variations come from segregation and crossing over in meiosis

  3. Source of Variations • Most variations come from: • Segregation • Crossing over

  4. Mutations • Mutations are sudden changes in the structure or amount of genetic material • Most mutations are harmful; some are beneficial (i.e. ones that allow species to meet needs of environment)

  5. Types of Mutations • 2 Main Types: • Chromosome Mutation = changes structure of all/part of chromosome • Gene Mutation = affects a gene on a chromosome • Mutation must be in DNA of sex cells in order for it to be passed on. • Mutations in body cells can’t be passed on.

  6. What Causes Mutations • Random error in DNA replication • Environmental Factors (called mutagens) • Radiation (X-rays) • UV light • Chemicals (chloroform and mustard gas)

  7. Chromosome Mutations • Translocation • One part of a chromosome is transferred to a non-homologous chromosome

  8. Chromosome Mutations 2) Inversion • One part of a chromosome is rotated (reverses order of genes)

  9. Chromosome Mutations 3) Addition • One part of a chromosome breaks off and attaches to a homologous chromosome

  10. Chromosome Mutations 4) Deletion • One part of a chromosome breaks off. This results in a loss of some genes • E.g. Angleman’s Syndrome (Chromsome #15)

  11. Chromosome Mutations 5) Non-disjunction • Addition or loss of a whole chromosome (ones that usually separate during meiosis remain together)

  12. Chromosome Mutations 6) Polyploidy • More than normal copy of chromosomes

  13. Gene Mutations • Genes tell the cell what order to arrange amino acids (to form proteins) • Changes in the DNA sequence will change the message transcribed into mRNA & likely change the protein • Types of Mutations: • Point Mutation • Base Substitution

  14. Point Mutation • Single nucleotide in a gene is changed • This is drastic as all triple codons beyond are changed • This makes the gene useless and the organism will lack the protein normally made by the gene

  15. Base Substitution • One base in a nucleotide is substituted for another. • This changes 1 codon and one amino acid • Results in a protein that doesn’t function normally • E.g. PKU • Substitution of GT to AT

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