Do now activity #4 What is the difference between co-dominance and incomplete dominance? What is the difference between a mono-hybrid punnet square and a di-hybrid punnet square?

Section 3-4: Genetic variation Essential Question: Why is there variation among organisms, even brothers and sisters? Key-terms: genetic variation, phenotype, gametes, chromosome, independent assortment, crossing over, mutations, genotype, alleles, law of segregation Learning Target Use a variety of data to support the claim that genetic variation results from three sources. Explain the source of variation among organisms. Section 3-4: Genetic variation

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What is genetic variation? overview What is genetic variation?

Genetic variation is differences among organisms of the same species overview Genetic variation is differences among organisms of the same species

Why do you think variation is important? overview Why do you think variation is important?

There are 3 sources of genetic variation. overview There are 3 sources of genetic variation.

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Source #1: Gene Shuffling Meiosis followed by sexual reproduction Most genetic variations are due to gene shuffling In humans this produces 8.4 million different combinations of genes Does not change the relative frequency of alleles in a population Source #1: Gene Shuffling

Gene shuffling A) Gene shuffling takes place when chromosomes cross over during meiosis. This produces variation in genes.

B) Genes are also shuffled due to independent assortment. Gene shuffling B) Genes are also shuffled due to independent assortment. Independent assortment allows alleles for one trait to segregate(separate) independently from alleles for another trait.

Gene shuffling Independent assortment and crossing over produces variation in gametes, which produces variation in the family.

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Source #2: Law of Segregation

Law of segregation Law of segregation happens when allele pairs from ___ & ___ separate and randomly unite during fertilization. Mom Dad Mom/dad

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mutations Change (mistake) in DNA code Source #3: Mutations

mutations A mutation is a change/mistake in the DNA

mutations 2 Types: 1. Gene Mutation 2. Chromosome Mutation

Gene Mutation: small change (example: Point Mutation)

Example: Point Mutation mutations Example: Point Mutation Base is substituted Will/won’t change protein Organism is affected if the protein changes

Point mutations change one (or a few) _____ . genes genes Point mutations change one (or a few) _____ .

Chromosomal Mutation: big change (example: frameshift mutation) mutations Chromosomal Mutation: big change (example: frameshift mutation)

Example: Frame-Shift Mutation mutations Example: Frame-Shift Mutation Nucleotide deleted/added Shift Changes protein and affects organism

mutations chromosomes Chromosomal mutations change the number or structure of ______________ .

mutations 4 Types: Deletion Duplication Inversion Translocation

Mutations can cause changes in the DNA.

Sometimes mutations can cause damage to cells that control growth.

Cells can lose control and _____ can spread to the whole body . mutations Cells can lose control and _____ can spread to the whole body . cancer cancer

mutations Causes Carcinogens Viral infections Radiation

Right now there is no cure for ______ . mutations Right now there is no cure for ______ . cancer cancer