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Use your knowledge of genetics to explain the following:

Use your knowledge of genetics to explain the following:. =. =. What?!?. X. X. 100%. 100%. Variations to Mendelian Genetics. Not all genetic traits strictly follow the laws discovered by Gregor Mendel Some variations can be observed in all animals including humans Eight types:

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Use your knowledge of genetics to explain the following:

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  1. Use your knowledge of genetics to explain the following: = = What?!? X X 100% 100%

  2. Variations to Mendelian Genetics

  3. Not all genetic traits strictly follow the laws discovered by Gregor Mendel • Some variations can be observed in all animals including humans • Eight types: • Incomplete dominance • Codominance • Multiple Alleles • Polygenic inheritance • Environmental • Sex-influenced traits • Sex-limited • Sex-linked traits

  4. Variation #1: Incomplete Dominance • A condition during the heterozygous condition (Bb) • The dominant alleledoes NOTcompletely overpower the recessive allele • There is a “BLENDING” of the traits Example: B = black b = white BB= black bb= white Bb= gray

  5. Example #1A: • In rabbits black fur is dominant over white fur. Incomplete dominanceis seen. Cross a black fur male with a white fur female Black= White= BB bb

  6. Another way to do it… Example: B = black W = white BB= black WW= white BW= gray

  7. Example #1B: Black= White= BB WW

  8. Variation #2: Codominance • A condition during the heterozygous condition (Bb) • The dominant allele does NOTcompletely overpower the recessive allele • BOTH traits are seen at the same time Example: B = black and b = white BB= black bb= white Bb= black and white

  9. Example #1A: PP pp Pp • In Rhododendrons, pink is dominant over white. This plant displays codominance. Cross a pink rhododendron with a white rhododendron. X =

  10. Example #1B: WW PW PP X =

  11. Variation #3:Multiple Alleles: • 3 or more alleles for 1 trait • Example: Blood Types = IA , IB , and i A and B are both Dominant over i Universal Donor: O Universal Recipient: AB Codominance

  12. Example #1: ?? IAi ii X =

  13. Example #2: ?? IBIB IAIB X =

  14. Back to Sponge Bob!!!! QUIZ on Incomplete Dominance & Blood Typing Problems Tomorrow!!!

  15. Variation #4: Polygenic Inheritance • Poly= • many • Genic= • Genes • Not all traits are controlled by one single set of genes. Polygenic inheritance is when many genes work together and interact to produce one trait that has many phenotypes. Examples: skin tone hair color

  16. Hair color is controlled by three sets of genes all working together to create various hair colors. • aabbcc AaBbCc AABBCC Blondest Medium Brown Blackest hair color hair color hair color (3 dominant/3 recessive)

  17. Skin tone is controlled by four sets of genes all working together to create one shade of skin tone aabbccdd AaBbCcDd AABBCCDD palest skin medium skin darkest skin tone tone tone (4 dominant/4 recessive)

  18. AABbCcDD X AaBBCcDd AABBCcDD AaBbccDd http://punnky.com/black-and-white-twins-born-for-the-second-time-in-the-same-family

  19. Variation #5: Environmental Factors • May affect the function and expression of a gene • Examples: • Climate = skin color • Radiation exposure = mutations

  20. Variation #6: Sex-influenced Traits • Autosomes: body chromosomes (non-sex) • 22 pairs or 44 total • Sex Chromosomes: sex determining • 1 pair or 2 total • Females have two X’s: XX • Males have only one X: XY • Sex-influenced: found on autosomes but the trait is dominant in one sex and recessive in the other

  21. Example of Sex-influenced: • Pattern Baldness: this autosomal gene is located on chromosome 20. Males must ONLYinherit one recessive gene while a female must inherit two.

  22. Variation #7: Sex-Limited Traits • Sex-limited: found on autosomes but the trait may only come to expression in ONE of the sexes • Example: Milk production in mammals

  23. Variation #8: Sex-Linked Traits • Controlled by a gene located ONLY on the X chromosome • Females must inherit one lethal genefrom BOTH her father and one from her mother (XX) • Males can inherit only one lethal genewhich comes from his mother (XY)

  24. Lethal gene: • A gene which causes a genetic disorder. It may or may not be deadly. • Example: • Deadly lethal gene: sickle cell anemia • Non-deadly lethal gene: pattern baldness

  25. Pedigree Charts:

  26. Sex-Linked Traits • Females get sex-linked diseases less often than males because statistically it is harder to inherit two “bad/lethal genes” than it is to inherit one

  27. Carrier: • a person who is normal but they “carry” the gene for a genetic disease and may pass that gene on to their child.

  28. Examples: Colorblindness

  29. Hemophilia • Blood cannot clot properly due to lack of platelets

  30. Duchenne Muscular Dystrophy • Gradual deterioration & weakening of muscle

  31. Sex-Linked Example #1: • In humans the gene for colorblindness (a) is recessive to the gene for normal vision (A). • Cross a colorblind male with a heterozygous/carrier female XaY x XAXa

  32. Sex-linked Example #2: • In humans the gene for hemophilia is recessive (h) to the gene for normal blood type (H). • Cross a hemophilic male with a female with normal blood whose father has hemophilia XhY x XHXh

  33. Back to Sponge Bob!!!! You will find the rest of these problems on your FINAL EXAM…no more unit exams, yea!!!

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