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Incomplete dominance

Incomplete dominance. Intermediate in phenotype. Blood type co-dominance. 6. 4. Genetics – Dominant Traits, Recessive. Hitchhiker’s Thumb. Dominant allele – hiker’s thumb Recessive – straight thumb. Tongue Rolling. Ability to Roll is dominant Inability to roll is recessive.

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Incomplete dominance

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  1. Incomplete dominance Intermediate in phenotype

  2. Blood type co-dominance 6 4

  3. Genetics – Dominant Traits, Recessive

  4. Hitchhiker’s Thumb • Dominant allele – hiker’s thumb • Recessive – straight thumb

  5. Tongue Rolling • Ability to Roll is dominant • Inability to roll is recessive

  6. Mid-Digital Hair • Presence of hair results from dominant allele • Absence results from recessive allele

  7. Widows Peak – a dominant trait (straight hairlines are recessive

  8. Pedigree analysis

  9. Genetic Disorders

  10. (Trisomy 21) = Down’s syndromeresults from 3 copies of chromosome pair 21

  11. Sickle Cell Anemia • Occurs most often in people of African descent • Is recessive on chromosome #11 • Abnormal blood protein changes shape of blood cell • Misshaped and carries less oxygen • Cells get less oxygen and suffocate with this disorder • Misshaped cells cause blocked capillaries and arteries - often strokes

  12. There is a interesting thing about sickle cell anemia. People who carry the tendency to have sickle cell anemia are less likely to die from malaria. Sometimes what is bad in one situation helps out in another.

  13. Malaria is a disease caused by a parasite that likes to set up housekeeping in the red cells.This parasite is carried by the Anopheles mosquito. Anopheles

  14. Albinism • Lack of pigmentation • Often sickly, tired and/or weak • Eyes lack pigment and appear red due to blood vessels

  15. Phenylketonuria (PKU) • Enzyme missing to break down the amino acid phenylalanine • Child usually does not survive long 

  16. Tay Sachs Disease • Harmful fatty acids produced in brain of a developing child • Enzymes not produced to reduce levels • Nerve cells are injured by the fatty acids • Characteristic cherry red spot in the eye develops • No cure • Death occurs by age 5 on average 

  17. ColorblindnessIf Mom has it, all her sons willand girls have a 50:50 chance of getting it Colorblind Mom: Xc XcOkay Dad: XY All daughters are carriers, but with one working X, they do not show colorblineness All sons colorblind – boo hoo, sniff, sniff

  18. Take the Test

  19. Colorblindness Gene is located on the X-Chromosome. Use of a Pedigree to Track Transmission

  20. Testing for Genetic DisordersKaryotyping – picturing human chromosomes

  21. Fetal Diagnosis for Genetic Problems – Amniocentesis & the Needle of Doom

  22. Overall lessons: Overall Lessons about Genetics • Your overall phenotype is controlled thousands of separated genes. • Some alleles are co-dominant so there can be more than two phenotypes per gene. • Genetics is never simple! – it becomes complicated when more than one gene is involved in producing a phenotype (Green eyes for ex.) • Pedigree analysis can help one determine human genotypes. • Harmful recessive genetic traits can persist in the population through carriers • Genetic testing will become more widespread. • Not all genetically-caused disorders are inherited. Some are caused by mutation of your genes by chemicals or radiation.

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