1. Mendel’s 3 Laws of Inheritance 1. Law of Dominance- Each trait is controlled by 2 factors: what is expressed Dominant- what is expressed Recessive- masked in presence of dominant P1P1 F1F1 F2F2

2. Mendel’s 3 Laws of Inheritance (cont.) 2. Law of Segregation- Each allele separates into different gametes (when does this happen??) Ex. Ww – one W goes in one sperm and the other w goes into another sperm Ww w W

3. Mendel’s 3 Laws of Inheritance (cont.) 3. Law of Independent Assortment- Gene pairs (homologous) will separate randomly into gametes during meiosis *Chromosomes line up randomly at metaphase plate

4. What is a dihybrid Cross?  A dihybrid cross allows us to predict possible outcomes of offspring that will have 2 traits simultaneously.  Ex: what would you get if you crossed a Brown- haired brown-eyed male with a blonde-haired blue-eyed female? How many of the children would have brown hair and brown eyes? Brown hair and blue eyes? Blonde hair and brown eyes? Blonde hair and blue eyes?

5. Setting up Dihybrid Crosses 1. Labels!! 2. Determine parent genotypes 3. Determine gametes (alleles to be passed down) The FOIL method 4. Set up punnet square 5. Determine outcome Phenotype Ratio

6. Dihybrid Crosses Looking at two different traits Ex. Hair color and eye color B=brown eyes b=blue eyes R=Brown hair r=blonde hair Mother is heterozygous for both traits Father is heterozygous for eye color and homozygous dominant for hair color

7. Example

8. More Practice Mickey Mouse is heterozygous for Round ears and homozygous for Black eyes. Minnie Mouse is homozygous for Floppy ears and heterozygous for Black eyes. Determine phenotype ratios. (B=black eyes, b=brown eyes, R=round, r= floppy.)

9. Do Now!!  Ariel and Prince Eric are curious to see what their babies will look like! Eric is heterozygous for black hair and Ariel has the recessive trait of red hair. Both are recessive for blue eyes. If they have 32 children, how many can we EXPECT to have red hair and blue eyes?

10. Gene Linkage  There are several genes on a chromosome  Gene Linkage:  When two genes are close to each other on the same chromosome

11. Gene Linkage (cont.) o Linked genes on a chromosome results in an exception to Mendel’s law of independent assortment o Linked genes usually do not segregate independently

12. Drosophila melanogaster (Fruit Flies) o First organism with linked genes o Linked genes typically travel together during crossing over

13. Chromosome Map  A map of genes on a chromosomes  Crossing over occurs more frequently between genes that are far apart

14. Polyploidy o Cells that contain more than 2 homologous sets of chromosomes o Ex. A triploid organism (3n) - means that it has three complete sets of chromosomes. Strawberries are octoploid!!

15. Pedigree  Shows history of a trait in a family  Allows researchers to analyze traits within a family

16. In a pedigree…  You can see how a genetic disorder runs in a family.  Carriers are individuals who are heterozygous for an inherited disorder but do not show symptoms.  Carriers can pass the allele for the disorder to their offspring

17. Symbols for Pedigree

19. Worksheet!!

20. Do Now!!  Fill in the genotypes for the following pedigree (shows recessive trait)  B=brown eyes  b = blue eyes

21. Incomplete dominance

23.  Both traits are dominant and expressed (no blending)  Ex: Roan Cows  white hair (H W ) is codominant with red hair (H R )  cows with genotype (H R H W ) have coats with a mixture of red and white hairs (roan)  Red + White = RED AND WHITE

24. Multiple alleles – 3 or more alleles that control a trait  Example: blood type!  Possible alleles: I A, I B, i  Which genotypes are heterozygous? Homozygous? GENOTYPESRESULTING PHENOTYPES IAIAIAiIAIAIAi Type A IBIBIBiIBIBIBi Type B IAIBIAIB Type AB iiType O

25. Antigens vs. Antibodies  Antigen: substance foreign to the body that causes an immune response:  Can act as surface markers  EX: type A antigens on surface of type A blood cells  Antibody: protein that reacts with specific antigen:  EX: Type B blood contains anti-A antibodies

26. Which is the universal donor? Universal acceptor?

27. Determine Blood Type  Determine the possible offspring of the following crosses  1. AB and O  2. Homozygous A and heterozygous B  3. AB and AB

28. Worksheet!!

29. What do you see?

31. Sex Linked Traits  Traits located on the sex chromosomes (X or Y)  X linked: gene is located on the X chromosomes  Y linked: gene is located on the Y chromosome  Ex: color-blindness is X-linked! *If X-linked, can males be carriers?

33. What are the chances of having a girl?  How would you go about solving it?

34. Sex-Linked Traits  A man who is color blind marries a woman that is heterozygous for color blindness. What is the chance of having a color blind boy?

35. Polygenic Traits o Polygenic traits arise from the interaction of multiple pairs of genes.