HEREDITY

1. HEREDITY Why we are the way we are?

2. REVIEW OF MITOSIS • Division of somatic (body) cells • Phases • Interphase • Prophase • Metaphase • Anaphase • Telephase • Cytokinesis • Produces 2 identical diploid cells

3. MEIOSIS • Division of gametes (reproductive) cells • Repeat all phases 2x’s, EXCEPT for interphase • Crossing Over • Chromosomes exchange parts during metaphase - creating different combinations of genes • Produces 4 differenthaploid cells

4. GENDER DIFFERENCES • Males • Meiosis occurs in testes • Starts @ puberty • Produces 4 mature sperm cells each time • Females • Meiosis occurs in ovaries • Begins/ends prior to birth • Produces 1 mature egg & 3 polar bodies • Shriveled cells lost their cytoplasm to single mature egg

5. CELL DIVISION T-CHART mitosismeiosis Type cells Same/different # of cells # chromosomes Term (# chrom)

6. MENDEL’S LAWS • Law of Dominance • Some traits show up throughout many generations. • Dominant – hide other traits • Recessive – can be hidden • Symbols • CAPITAL = dominant • lower = recessive • Terms • Genotype • Genetic make-up • TT, Tt = tall • tt = short • Phenotype • Physical appearance • Tall or short

7. MENDEL’S LAWS • Law of Segregation • Traits have multiple forms (dom & rec) – also called alleles • Inherit one form from each parent • Terms: • Homozygous (purebred) • 2 identical alleles • TT or tt • Heterozygous (hybrid) • 2 different alleles • Tt

8. MENDEL’S LAWS • Law of Independent Assortment • Genes not tied together • Allows for differences between individuals of same species • Example: • Not everyone who is tall has to have brown hair

9. GENETIC PROBABILITY • Punnett square • Grid used to predict genetic probability • Chance that offspring will receive certain trait • Monohybrid • Grid that looks at only 1 trait

10. MONOHYBRID CROSSES • Identify the genotypes of the parents • This will determine the size of the square • Place 1 genotype on the top of the square & the 2nd along left • Fill in the center squares • Determine the genotypic & phenotypic ratios of the offspring

11. MONOHYBRIDS Example #1 A man who is homozygous for brown eyes and a women who is homozygous decide to have children. If brown eyes are dominant, what color eyes will their children have?

12. MONOHYBRIDS Example #2 If both the mother and father are heterzygous for eye color, what color eyes will their children have?

13. MONOHYBRIDS Example #3 In monkeys, long tails are dominant over short tails. If a homozygous recessive female mates with a heterozygous male, what will their offspring look like?

14. DIHYBRID CROSS • Identify the genotypes of the parents • Determine the possible gametes each parent could provide. • This will determine the size of the square • Place the gametes of the parents on the top & along left side • There will be 2 letters/block • Fill in the center squares • There will be 4 letters w/in each block • Determine the genotypic & phenotypic ratios of the offspring

15. DIHYBRIDS Example #4 Assuming that spots are dominant over no spots & horns are dominant over no horns, what would the offspring of the following cows look like? Male – homozygous spots & heterozygous for horns Female – heterozygous spots with no horns

16. DIHYBRIDS Example #5 In pigs, pink is dominant to white and curly tails are dominant to straight tails. Male –white w/ and purebred curly tail Female – pure pink w/ straight tail

17. DIHYBRIDS Example #6 Brown eyes dominant over blue & separate brows are dominant over unibrows Mom & Dad both heterozygous both traits

18. INCOMPLETE DOMINANCE • Dominant gene not completely hide the recessive gene • Results in a blend or mix of the two features • Results in 3 possible phenotypes • Heterozygous genotype now has its own physical appearance (phenotype) • Often seen in shapes & colors • Example: • TT  tall • tt  short • Tt  medium

19. INCOMPLETE PROBLEMS • Example #7 In carnations, Red is dominant over white & a mix of the two create pink. What type of flowers would be produced by crossing a white carnation with a pink carnation?

20. INCOMPLETE PROBLEMS Example #8 Straight hair is dominant over curly hair & a combination of genes results in wavy hair. What would the children of two wavy haired parents look like?

21. CODOMINANCE • A condition where both alleles of a gene are active (dominant) • No recessive gene • A heterozygous individual would have both physical features present • Condition is most often seen in hair, feathers, fur & skin color • Example: Cows • B  Black • W  white • BW  Black & White

22. COMDOMINANT PROBLEMS Example #9 Tabby cats are the result of codominance, the genes for black and tan are both present. What would be the result of a black cat & a tabby cat having kittens?

23. COMDOMINANT PROBLEMS Example #10 A roan cow is one that has both red & white hairs. What would the calves of two roan cows look like?

24. POLYGENIC INHERITANCE • Poly = many • Genic = genes • Many physical features are controlled by more than 1 gene • What makes us look so different • Example: • Eyes • Size • Shape • Slant • Distance • Color • Lash length

25. SEX DETERMINATION • 22 pairs autosomes • Same males & females • Basic physical info • 1 pair sex chromosomes • XX  female • XY  male

26. SEX-LINKED TRAITS • Genes carried on x chromosome • Most are recessive and so rarely seen in females • Males only need 1 recessive gene to show trait (XhY) • Females need 2 recessive genes to show trait (XhXh) • Females can be Carriers • Heterozygous, have 1 recessive gene but do NOT exhibit the trait • XHXh • Examples: • Red Green colorblindness • Hemophilia • Muscular Dystrophy • Male Pattern Baldness • Fragile X syndrome

27. SEX-LINKED PROBLEMS Example #11 If a colorblind woman is married to a man with normal vision, what are the chances that their children will be colorblind?

28. SEX-LINKED PROBLEMS Example #12 If a man with hemophilia and a completely normal female decide to have children, will they have to worry about their children having hemophilia?

29. SEX-LINKED PROBLEMS Example #13 If a bald man and a woman who carries the gene for baldness have children, will all of their children be bald?

30. PEDIGREE • Family tree shows how a trait or genetic disorder is passed through the generations • Symbols: • Male • Female • Marriage • Death/divorce • Relationship • Twins • Miscarriage • Symbols: • Traits/diseases • Person w/ trait • Person w/o trait • Carrier • Format • Oldest  youngest (left) (right) • Generations numbered along left side • Arrow points to individual

31. PEDIGREE EXAMPLE

32. MULTIPLE ALLELES • Trait that requires more than 1 gene to determine phenotype • Blood types • Type A  IAIA, IAIi • Type B  IBIB, IBIi • Type AB  IAIB • Type O  ii • Blood types are named by the types of antigens found in the red blood cells • Antigen  protein specific to individual • AB  universal receiver • (take all types since their blood contains all possible antigens) • O  universal donor • (give blood anyone since their blood contains no antigens)

33. BLOOD TYPE PROBLEMS Example #14 If the mother is homozygous for A and the father is heterozygous for B, what possible blood types could they provide to their children?

34. BLOOD TYPE PROBLEMS Example #15 If both mom and dad have type AB blood, what possible blood types could they provide to their children?

35. BLOOD TYPE PROBLEMS Example #16 Mr. & Mrs. Doe had a child named Jim at the same time Mr. & Mrs. Roe had their son Joe. The couples thought their children had been switched at birth and demanded blood tests to prove paternity. Use the test results to determine if there was a mix-up. Mr. Roe – A Mrs. Roe – A Joe – O Mr. Doe – O Mrs. Doe – AB Jim – A