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Chapter 11.6

Chapter 11.6. Mutations. Definition-. Mutation- a change in the DNA nucleotide sequence Types of mutations: Base substitution –replaces one DNA nucleotide base with another one. Base insertion- a DNA nucleotide base is added. Base deletion- a DNA nucleotide base is deleted or removed.

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Chapter 11.6

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  1. Chapter 11.6 Mutations

  2. Definition- • Mutation- a change in the DNA nucleotide sequence • Types of mutations: • Base substitution –replaces one DNA nucleotide base with another one. • Base insertion- a DNA nucleotide base is added. • Base deletion- a DNA nucleotide base is deleted or removed. • Each mutation can cause a different protein to be made. • Base substitutions are the least harmful. • Why? • Some substitutions cause no change to the resulting protein; • 64 codons=more than 1 codon can code for the same amino acid • Leucine= CUU, CUC, CUA, CUG,UUA, UUG • Insertion and Deletion mutations are more severe • Affects all the nucleotides downstream from the insertion or deletion. • Resulting in many different codons and many new amino acids. • Affects the protein being made- protein may not function properly.

  3. What causes a mutation? • Random errors during DNA replication. • Physical and chemical agents- mutagens. • high energy radiation- x-rays and ultraviolet light ( shorter wavelengths). • Chemicals that are similar to DNA bases and cause incorrect base-pairing when incorporated into the DNA. • Not all mutations are harmful. • Mutations in DNA can be passed on to offspring. • Mutations are the source of genetic diversity in the living world.

  4. Gene Regulation • All the cells in a multicellular organism carry the complete genetic code in their nucleus. • Cell specialization requires genetic specialization. • Only a tiny fraction of the available genes needs to be expressed in cells of different tissues throughout the body.

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