1/11/15 Date:1/11/15Topic:Dihybrid CrossesPage # ___ Brown eyes (B) is dominant to blue eyes. Black hair (R) is dominant to red hair. Freckles (F) are dominant to non-freckles. A person has the genotype: Bb rr FF What do they look like? Today in Room 326 Date:1/11/15Topic:Dihybrid CrossesPage # ___ HW: WORK ON SCIENCE FAIR PROJECT!! GATHER ALL SUPPLIES!! CONTENT OBJ: SW complete Punnet squares for two traits using a dihybrid cross LANG. OBJ: SW read about sickle cell anemia and describe in writing how it confers resistance to malaria ANNOUNCEMENTS: Science Fair Project AGENDA: Multiple genes (5 min) Dihybrid Cross notes & practice (15 min) Individual/partner practice (worksheet) (20 min) Genetics quiz (25 min) Science Fair Planning (10 min) Review and move on What is a monohybrid cross*? Deals with the inheritance of a single trait Example: pea color: Y = yellow, y = green YY = ______________ Yy = ______________ 2 Traits? Some of Mendels experiments involved two traits, such as BOTH pea color and pea shape Wrinkled peas Round peas (green & yellow) Pea Genotypes Yellow = Y, green = y Round = R, wrinkled = r Genotype of purebreeding? Yellow wrinkled __________ Round green __________ What if you breed them? Two genes If the genes are on separate chromosomes, do they assort into the gametes TOGETHER, or INDEPENDENTLY? Thoughts??? Well, thats NOT right! BINGO! Law of Independent Assortment As recognized by Mendel during his work with breeding pea plants Allele pairs separate independently during the formation of gametes Meaning, traits are transmitted to offspring independently of one another* (A pea will separately pass on its green trait from its round trait, it does not have to pass on a green round trait) (copy into notebooks!)** Yellow wrinkled pea x Green round pea Yyrr x yyRr ^^ Copy these genotypes into your journals, and write the phenotypes next to them** In journal Dihybrid Practice Complete the worksheet Genetics: Why We Care We have learned lots of big words, and sometimes confusing concepts Heterozygous = have two DIFFERENT alleles (Aa) Homozygous = have two of the SAME allele (AA or aa) Carrier = someone with two DIFFERENT alleles, that carries the trait Why do you think we care? Genetics: Why We Care Sickle Cell Disease & Malaria Resistance Read handout (new words defined on sheet) Answer questions on back: How does sickle cell disease relate to malaria resistance? How does sickle cell disease relate to malaria resistance? If you had a choice, which genotype for the hemoglobin gene would you choose? Sickle Cell Anemia Shape of red blood cell (sickle) makes it difficult for hemoglobin to carry oxygen Malaria Relationship Death from malaria Genetics Quiz Science Fair Project!!