MutationsMutations

What is a mutation?What is a mutation?

Changes in the DNA sequence that Changes in the DNA sequence that affect genetic informationaffect genetic information• Normal:Normal:

Thesunwashotbuttheoldmandidnotgethishat.Thesunwashotbuttheoldmandidnotgethishat.The sun was hot but the old man did not get his hat.The sun was hot but the old man did not get his hat.

• Translation changed in ribosome:Translation changed in ribosome:t hes unw ash otb utt heo ldm and idn otg ish at.t hes unw ash otb utt heo ldm and idn otg ish at.

• Missing letter or base:Missing letter or base:the sun wsh otb utt heo ldm and idn otg ish at.the sun wsh otb utt heo ldm and idn otg ish at.

Genetic mutationsGenetic mutations

Not all are harmfulNot all are harmful Most cause little/no changeMost cause little/no change Have to be reproductive cell Have to be reproductive cell

mutations to repeat in future mutations to repeat in future generationsgenerations

Somatic mutations not inheritableSomatic mutations not inheritable

What causes What causes mutations?mutations?

Environmental Environmental agentsagents• UV light, chemicals, UV light, chemicals,

radiationradiation

Meiosis Meiosis • more/less more/less

chromosomeschromosomes

Mistakes in DNA Mistakes in DNA replicationreplication

What happens when there is a What happens when there is a mutation?mutation?

The mistake can cause the cell to make an incorrect The mistake can cause the cell to make an incorrect proteinprotein• see a see a different phenotypedifferent phenotype than normal ex. White than normal ex. White

BuffaloBuffalo If the mutation occurs in a single type of cell, If the mutation occurs in a single type of cell,

• it will affect it will affect only the cell that carries itonly the cell that carries it ex. Skin cells ex. Skin cells If the mutation occurs in a sex cell, If the mutation occurs in a sex cell,

• it can be it can be passed to the offspring and affect their passed to the offspring and affect their phenotypephenotype

Mutations can introduce Mutations can introduce genetic variationgenetic variation• the change can be the change can be helpful, harmful or neitherhelpful, harmful or neither

Where do they happen?Where do they happen?

Gene MutationsGene Mutations• replicationreplication• transcriptiontranscription• translationtranslation

Chromosome Structural Changes Chromosome Structural Changes • MitosisMitosis• MeiosisMeiosis

Gene MutationsGene Mutations

Point MutationsPoint Mutations• involve one nucleotide involve one nucleotide • single point in a DNA sequencesingle point in a DNA sequence

Substitute one base for anotherSubstitute one base for another

Gene MutationsGene Mutations

Frameshift 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 acids different group of amino acids • changes the protein functionchanges the protein function

Chromosome Structural ChangesChromosome Structural Changes

DeletionDeletion- - loss of all or part of loss of all or part of

chromosomechromosome

- missing genes - missing genes may prove fatalmay prove fatal

DuplicationDuplication- - segment repeatedsegment repeated

- usually harmless- usually harmless

Chromosome Structural ChangesChromosome Structural Changes

InversionInversion- - connection broken & connection broken & sequence reversedsequence reversed- may be fatal- may be fatal

TranslocationTranslocation- non-homologous - non-homologous chromosomes sharing chromosomes sharing or exchanging or exchanging information information