1. 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?

2. 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

3. Don’t forget to chunk your notes!

4. What is genetic variation?
overview
What is genetic variation?

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

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

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

8. Don’t forget to chunk your notes!

9. 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

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

11. 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.

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

13. Don’t forget to chunk your notes!

14. Source #2: Law of Segregation

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

16. Don’t forget to chunk your notes!

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

18. mutations
A mutation is a
change/mistake
in the DNA

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

20. Gene Mutation: small change (example: Point Mutation)

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

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

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

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

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

26. mutations
4 Types:
Deletion
Duplication
Inversion
Translocation

27. Mutations can cause changes in the DNA.

28. Sometimes mutations can cause damage to cells that control growth.

29. 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

30. mutations
Causes
Carcinogens
Viral infections
Radiation

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