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More Punnett squares

Explore the fascinating world of genetic inheritance, focusing on the principles of complete dominance, incomplete dominance, codominance, and the role of multiple alleles. Learn how different alleles interact to determine traits, as well as how inheritance patterns, such as blood types and sex-linked traits, affect phenotype expressions. Through examples like flower colors and human blood types, this overview explains gametic possibilities, genotypic and phenotypic ratios, and the implications of polygenic and sex-linked inheritance, providing a comprehensive understanding of heredity.

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More Punnett squares

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  1. More Punnett squares

  2. Complete Dominance • Involves dominant and recessive alleles • dominant allele always overpowers the recessive allele in appearance

  3. Incomplete Dominance • Neither allele is dominant or recessive • Organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parents

  4. Incomplete Dominance • Ex: Cross a red flower (RR) with a white flower (WW) and the offspring will be pink (RW)!

  5. Incomplete Dominance (RR) • In another flower, if red ____ and blue ____ flowers are crossed, they produce a 3rd purple ____ flower • What would be the genotypic ratio and phenotypic ratio if you crossed two purple flowers? (BB) (RB)

  6. Incomplete Dominance • Cross of two purple flowers_RB_ X _RB_ • What are gamete possibilities? • genotypic ratio 1RR : 2RB : 1BB • phenotypic ratio 1red : 2 purple : 1 blue R B R B

  7. Codominance • Neither allele is dominant or recessive • Parents with different phenotypes produce an offspring with a third phenotype • Third phenotype will show bothparental phenotypes simultaneously (at the same time)

  8. Codominance • In cattle and horses, if you cross a pure red (RR)with a pure white (WW), you get (RW) which produces the color roan.

  9. Codominance • These cattle or horses actually have both red and white hairs intermixed, or are spotted. Roan is a third phenotype. • If you cross a roan with a white… • RW X WW R W W W

  10. What is it?! + = = +

  11. Multiple alleles • two or more possible alleles for the same gene within a population • Thus multiple alleles • However, individuals within the population are only able to holdtwo of them • Non-human examples: rabbit fur color, mice skin color, eye color in flies, wing size in flies

  12. Multiple Alleles • Blood type in humans • The _four_ different blood types: • A, B, O, and AB • Blood types are produced by three_ different alleles: • A, B and O

  13. Genotype for Blood Type I and i used in genotype I used with A and B i used with O A and B are dominant over O: A and B are codominant Ex: Genotype: AA is IAIA

  14. Blood type chart Blood type AB is an example of codominance in humans

  15. Blood Type Punnett Square • Draw a Punnett square showing all the possible genotypes for the offspring produced by a type “O” mother and an a Type “AB” father. i i Cross: ii x IAIB IA IB

  16. Blood Type Punnett Square • Cross a female with blood type A and a male with heterozygous B blood type. • Complete ratios (phenotypic and genotypic) • A male with blood type B has a child with a woman who has blood type A. The child is blood type O. What is the genotype of the male and female? Show your work.

  17. How does blood type work?

  18. Blood transfusions

  19. Rh factor: Rh for Rhesus Monkey • Positive vs Negative Blood types • Positive: protein is present • Dominant trait • Negative: protein is absent • Recessive trait

  20. Polygenic traits • Traits controlled bytwo or more genes (one gene has two alleles) • Show a wide range of phenotypes • Phenotype is produced by the interaction of more than one pair of alleles

  21. Examples of polygenic traits in humans

  22. Example of polygenic traits in humans

  23. Examples of polygenic traits in humans

  24. Sex-linked traits • Every new born has a 50% chance of being female and a 50% chance being male • DAD: X Y • Sperm contains either: • MOM: X X • Eggs all contain: X Y or Y X X X X

  25. Sex-Linked traits • The X chromosome contains many genes, whereas the Y chromosome contains only a few genes • sex-linked genes: genes located on one of the sex chromosomes (X or Y) but not the other • most sex-linked genes are X-linked genes

  26. Examples of sex-linked traits: X-linked • Colorblindness: more common in males than females • Hemophilia: more common in males than females Both colorblindness and Hemophilia are recessive traits

  27. Colorblindness

  28. Do any of these pictures look the same?!

  29. Test time!

  30. Colorblind: X-linked trait • C- normal vision • c- colorblind • You must incorporate XX (mom) and XY (dad) • This is how to set it up: • (remember colorblindness is X-linked!)

  31. Punnett Square • Cross a female who is a carrier for colorblindness with a normal vision man. • Cross a normal vision woman (homozygous) with a colorblind man.

  32. Hemophilia: X-linked recessive trait • Hemophilia is the inability for blood to clot • Your blood clots every time you get a papercut • H: normal clotting • h: hemophilia • Make a key for hemophilia: • Normal female: Normal Male: • Female Carrier: Can a man be a carrier? • Female with hemophilia: Male with:

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