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Start Up March 6, 2008

Start Up March 6, 2008. Get out A-13: SA p. 322 Refer to Notes and answer the following question in your Start up. Describe and give examples of the 4 Patterns of Inheritance that you have learned. Complete dominance/recessiveness Incomplete dominance Co-dominance Sex-linked.

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Start Up March 6, 2008

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  1. Start Up March 6, 2008 • Get out A-13: SA p. 322 • Refer to Notes and answer the following question in your Start up. • Describe and give examples of the 4 Patterns of Inheritance that you have learned. • Complete dominance/recessiveness • Incomplete dominance • Co-dominance • Sex-linked

  2. Start Up Answers • Complete- one trait completely masks another – ex. Tall vs. Short in peas. • Incomplete dominance- traits are shown as a blend– ex. Snapdragons- red, white, pink • Co-dominance- both traits are exhibited- horse coat color- red, white, and roan (some white hairs and some red hairs) • Sex-linked- Trait on sex chromosome- like Hemophilia or color blindness

  3. Homework: • A-13 SA p. 322 Due Tomorrow • A-15 Questionable Cases involving Genetics Due- Tomorrow • Chapter 12 Test- Tuesday, March 11`

  4. Homework Help • SA p. 322 #2 Red and white eyed fruit flies R= red; r= white Allele on X chromosome XRXR = red XRY = red XRXr = red XrY = white XrXr = white

  5. Section 12.3 Summary – pages 323 - 329 Multiple Alleles Govern Blood Type • Mendel’s laws of heredity also can be applied to traits that have more than two alleles. • The ABO blood group is a classic example of a single gene that has multiple alleles in humans.

  6. Alleles for ABO Type Symbol A IA or A Both A & B are B IB or B dominant to O, but Co- dominant to each other. O i or O Recessive to both A & B

  7. Section 12.3 Summary – pages 323 - 329 Multiple Alleles Govern Blood Type Human Blood Types Genotypes Phenotypes Surface Molecules A A lAlA or lAli B B lBlB or lBi lAlB A and B AB None ii O

  8. Section 12.3 Summary – pages 323 - 329 The ABO Blood Group • The gene for blood type, gene l, codes for a molecule that attaches to a membrane protein found on the surface of red blood cells. • The lA and lBalleles each code for a different molecule. • Your immune system recognizes the red blood cells as belonging to you. If cells with a different surface molecule enter your body, your immune system will attack them.

  9. Section 12.3 Summary – pages 323 - 329 Phenotype A: Blood type A • The lA allele is dominant to i, so inheriting either the lAi alleles or the lA lA alleles from both parents will give you type A blood. Surface molecule A • Surface molecule A is produced.

  10. Section 12.3 Summary – pages 323 - 329 Phenotype B: Blood type B • The lB allele is also dominant to i. Surface molecule B • To have type B blood, you must inherit the lB allele from one parent and either another lB allele or the i allele from the other. • Surface molecule B is produced.

  11. Section 12.3 Summary – pages 323 - 329 Phenotype AB: Blood type AB • The lA and lB alleles are codominant. Surface molecule B • This means that if you inherit the lA allele from one parent and the lB allele from the other, your red blood cells will produce both surface molecules and you will have type AB blood. Surface molecule A

  12. Section 12.3 Summary – pages 323 - 329 Phenotype O: Blood type O • The i allele is recessive and produces no surface molecules. • Therefore, if you are homozygous ii, your blood cells have no surface molecules and you have blood type O.

  13. Section 12.3 Summary – pages 323 - 329 The importance of blood typing • Determining blood type is necessary before a person can receive a blood transfusion because the red blood cells of incompatible blood types could clump together, causing death.

  14. Blood type A Blood cells have surface protein A

  15. Blood type B Blood cells have surface protein B

  16. Blood type AB Blood cells have surface proteins A and B

  17. Blood type O Blood cells have no surface proteins

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