Gene Mutations

Mutation Mutation – changes in the genetic material. Gene Mutations Chromosomal Mutations

Gene Mutation Point mutation: changes in one/few nucleotides Substitutions: one base is changed to another only affects one amino acid

Gene Mutation Frameshift mutations: shift codon reading frame Insertions: base is inserted into the DNA Deletion: base is removed from DNA every amino acid that follows the point is changed Proteins cannot perform their normal functions

Chromosomal Mutation Changes in the number or structure of chromosomes. Change the location of genes and the number of copies of a gene. Deletion: loss of all or part of chromosome Duplication: produce an extra copy of chromosome part Inversion: reverse the direction of part of chromosomes Translocation: part of one chromosome breaks off and attaches to another

Chromosomal Mutations

Significance of Mutations Many have no effect Some produce defective proteins that disrupt normal activity Source of genetic variability Polyploidy: organism has an extra set of chromosomes plants are often larger and stronger bananas and citrus fruits

Gene Regulation DNA regulatory sites: proteins bind to regulate transcription controls if a gene is turned on or off

Bacteria Gene Regulation operon - a group of genes that work together lac operon allows lactose to be used as food lac genes are turned off by repressors and turned on by the presence of lactose lac repressor binds, the operon is off & transcription doesn’t occur Add lactose, the repressor changes shape and falls off the operator Transcription can occur

Development & Differentiation During development, cell differentiate - become specialized in structure and function Hox genes control embryos’ cell differentiation Mutations can completely change development