Homozygous Dominant and Recessive and Heterozygous

Genetics Review

 Homozygous Dominant and Recessive and Heterozygous  Alleles  Genotype and Phenotype  Autosomes  Mono and Di-hybrid crosses

Cross two pea plants. One pea plant is homozygous for terminal flower position and heterozygous for seed coat and the other plant is homozygous for axial flower position and also heterozygous for seed coat. F – axial flower position f - terminal flower position S – gray seed coat s – white seed coat

 Sex linked Traits

A colorblind man XcY marries a woman whose father is color blind XCXc . Show the gametes of the man and woman using a punnett square. Give the geno and phenotypinc ratios – What is the probability that their daughters will be colorblind? What is the probability that their sons will have normal color vision?

A man with hemophilia XhY marries a woman whose blood clots normally XHXH. Show the geno and phenotypic ratios using a punnett square. What is the probability that their daughters will carry the hemophilia gene? What is the probability their sons will have hemophilia?

 Blood Typing Blood Type Antigen Antibodies Acceptable Unacceptable (protein) Donors Donors A A Anti-B A and O B and AB B B Anti-A B and O A and AB AB A and B None A, B, AB & O none O None Anti-A & O A, B & AB Anti-B

Universal Donor – Blood Type O Universal Recipient – Blood Type AB

A woman with blood type AB marries a man with blood type O. Show the geno and phenotypic ratios of the possible offspring Cross a man with heterozygous Rh factor and heterozygous Type A blood with a woman who is homozygous negative Rh and homozygous Type B blood. What will the genotypic and phenotypic ratios of the offspring be?

 Monogenetic (one-gene) Traits Tongue Rolling, Blood Type, Ear lobe attachment, Hair Line, etc.

 Polygenetic (many –gene) Traits I.Q., Height, Weight, Eye Color, Skin Tone, etc.

 Co-dominance – a condition in which both alleles of a gene are expressed (sometimes get splotchy and speckled) Examples 1. Speckled Chickens 2. Cattle 3. Blood Types

 Using pedigree charts

Free ear lobes is a dominant trait. Attached ear lobes is a recessive trait. Use the symbols E and e to label each individual. The shaded regions show individuals homozygous for attached ear lobes. Nearsightedness (Myopia) is a recessive triat. Use the symbols N and n to label the genotype of each of the numbered individuals. The shaded individuals are homozygous for the Myopia trait.

3 4 5 6

7 8 9 10

11 12 13

 Incomplete Dominance – only one of the alleles is active – the heterozygous phenotype is somewhere in between the homozygous phenotypes Examples 1. Carnation Flowers (flowers in general) 2. Hair 3. Sicle Cell Anemia