Genetic Mutations

Genetic mutations Not all are harmful Most cause little/no change Have to be reproductive cell mutations to repeat in future generations Somatic mutations not inheritable

What are mutations? Changes in the genetic sequence that affect genetic information Two types Gene mutations Chromosomal mutations Normal Human Karyotype Rust’s Disease

Examples of mutations Changes in the DNA sequence that affect genetic information Normal: Thesunwashotbuttheoldmandidnotgethishat. The sun was hot but the old man did not get his hat. Translation changed in ribosome: t hes unw ash otb utt heo ldm and idn otg ish at. Missing letter or base: the sun wsh otb utt heo ldm and idn otg ish at.

How do mutations happen? Environmental agents UV light, chemicals, radiation Meiosis more/less chromosomes Mistakes in DNA replication

What happens when there is a mutation? The mistake can cause the cell to make an incorrect protein see a different phenotype than normal ex. White Buffalo If the mutation occurs in a single type of cell, it will affect only the cell that carries it ex. Skin cells If the mutation occurs in a sex cell, it can be passed to the offspring and affect their phenotype Mutations can introduce genetic variation the change can be helpful, harmful or neither

Where do they happen? Gene Mutations Chromosome Structural Changes replication transcription translation Chromosome Structural Changes Mitosis Meiosis

Gene Mutations Point Mutations Substitute one base for another involve one nucleotide single point in a DNA sequence Substitute one base for another

Gene Mutations Frameshift insertion or deletion of a base shifts entire sequence for translation different group of amino acids changes the protein function

Review Gene mutations Point mutations – mistakes with 1 nucleotide Substitution of the wrong nucleotide (nitrogen base) in place of correct one Frameshift mutations – occur when a nucleotide is either inserted or deleted, altering the trios of nitrogen bases More severe than point mutations because it effects all of the amino acids in the protein

Chromosome Structural Changes Deletion - loss of all or part of chromosome - missing genes may prove fatal Duplication - segment repeated - usually harmless

Chromosome Structural Changes Inversion - connection broken & sequence reversed - may be fatal Translocation - non-homologous chromosomes sharing or exchanging information

Review Chromosomal mutations Change in the number or structure of the chromosomes Deletion Duplication Inversion translocation