8.7 Mutations Notes

Gene Mutations:

• Mutations that affect a single gene
• POINT MUTATION: one nucleotide is substituted for another DNA. May be fixed by DNA Polymerase
• FRAMESHIFT MUTATION: insertion or deletion of a nucleotide in a DNA sequence, SHIFTS the entire sequence

Chromosomal Mutations:

• Affects the entire chromosome (many genes)
• GENE DUPLICATION: caused by exchange of unequal segments during crossing over. One chromosome has 2 copies of some genes and the other has no copies.
• TRANSLOCATION: movement of piece of 1 chromosome to a non-homologous chromosome.

Potential Impact:

• Chromosome mutations typically have a large effect on an organism
• Point mutatiosn may result in premature STOP codons or amino acids with very different properties from the correct amino acid

Silent:

• Some mutations have no apparent effect.
• A point mmutation may not change the amino acid coded for.
• Even if a change occurs, it may be in the non-coding region that has no apparent effect.

Mutagens:

• Agents that can change DNA.