Mutations

What is a mutation? b Changes in the DNA sequence that affect genetic information Normal: Thesunwashotbuttheoldmandidnotgethishat. The sun was hot but the old man did not get his hat.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.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.Missing letter or base: the sun wsh otb utt heo ldm and idn otg ish at.

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

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

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

Where do they happen? b Gene Mutations replicationreplication transcriptiontranscription translationtranslation b Chromosome Structural Changes MitosisMitosis MeiosisMeiosis

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

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

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

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