Mutations

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Mutations

  1. 1. 8.7 Mutations KEY CONCEPT Mutations are changes in DNA that may or may not affect phenotype.
  2. 2. 8.7 Mutations Some mutations affect a single gene, while others affect an entire chromosome. • A mutation is a change in an organism’s DNA. • Many kinds of mutations can occur, especially during replication. • A point mutation substitutes one nucleotide for another. mutated base
  3. 3. 8.7 Mutations • Many kinds of mutations can occur, especially during replication. – A frameshift mutation inserts or deletes a nucleotide in the DNA sequence.
  4. 4. 8.7 Mutations • Chromosomal mutations affect many genes. • Chromosomal mutations may occur during crossing over – Chromosomal mutations affect many genes. – Gene duplication results from unequal crossing over.
  5. 5. 8.7 Mutations • Translocation results from the exchange of DNA segments between nonhomologous chromosomes.
  6. 6. 8.7 Mutations Mutations may or may not affect phenotype. • Chromosomal mutations tend to have a big effect. • Some gene mutations change phenotype. – A mutation may cause a premature stop codon. – A mutation may change protein shape or the active site. – A mutation may change gene regulation. blockage no blockage
  7. 7. 8.7 Mutations • Some gene mutations do not affect phenotype. – A mutation may be silent. – A mutation may occur in a noncoding region. – A mutation may not affect protein folding or the active site.
  8. 8. 8.7 Mutations • Mutations in body cells do not affect offspring. • Mutations in sex cells can be harmful or beneficial to offspring. • Natural selection often removes mutant alleles from a population when they are less adaptive.
  9. 9. 8.7 Mutations Mutations can be caused by several factors. • Replication errors can cause mutations. • Mutagens, such as UV ray and chemicals, can cause mutations. • Some cancer drugs use mutagenic properties to kill cancer cells.
  10. 10. 8.7 Mutations Mutations can be caused by several factors. • Replication errors can cause mutations. • Mutagens, such as UV ray and chemicals, can cause mutations. • Some cancer drugs use mutagenic properties to kill cancer cells.

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