1. Chapter 11.6 Mutations

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

3. What causes a mutation? Random errors during DNA replication. Random errors during DNA replication. Physical and chemical agents- mutagens. Physical and chemical agents- mutagens. high energy radiation- x-rays and ultraviolet light ( shorter wavelengths). 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. Chemicals that are similar to DNA bases and cause incorrect base-pairing when incorporated into the DNA. Not all mutations are harmful. Not all mutations are harmful. Mutations in DNA can be passed on to offspring. Mutations in DNA can be passed on to offspring. Mutations are the source of genetic diversity in the living world. 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. All the cells in a multicellular organism carry the complete genetic code in their nucleus. Cell specialization requires genetic specialization. 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. Only a tiny fraction of the available genes needs to be expressed in cells of different tissues throughout the body.