Mutations: Changes in Genes

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Mutations Changes in Genes
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Point Mutations

• A point mutation is a change in a single base
  pair in the DNA.
• Analogy
• THE CAT ATE THE RAT -original
• THE BAT ATE THE RAT -point mutation

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Example of a Point Mutation

• Sickle cell anemia is caused by a single point
  mutation in the gene for hemoglobin (the protein
  that makes up red blood cells).

Sickle cell blood cell compared to normal blood
cell
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• Not all point mutations result in defective
  proteins.
• Example may not change amino acid sequence.

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Frameshift Mutation

• Frameshift mutation Insertion or deletion in a
  base. Shifts the codon pattern.
• Analogy
• THE CAT ATE THE RAT- original
• THE ATA TET HER AT - frame shift (C
  deleted)

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• Frame shift
• Changes the reading pattern of the 3 nucleotide
  codon sequence
• Therefore, changes the entire amino acid sequence
  after the mutation.
• Likely to be harmful.

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• Mutations can occur as random mutations during
  replication of DNA.
• Mutagens Factors that make mutations more
  likely to occur.
• - UV Radiation
• - certain chemicals (carcinogens)