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Codominance and Sex-linked traits

Codominance and Sex-linked traits. CODOMINANCE. 2 alleles are dominant and both are expressed. Most common examples are blood type and flower color. Blood Type. 3 possible alleles: A, B, O 4 possible PHENOTYPES: A AB B O.

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Codominance and Sex-linked traits

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  1. Codominance and Sex-linked traits

  2. CODOMINANCE • 2 alleles are dominant and both are expressed Most common examples are blood type and flower color.

  3. Blood Type • 3 possible alleles: A, B, O • 4 possible PHENOTYPES: A AB B O Both alleles A and B are dominant. When both A and B alleles are present, they are both expressed. Type O is recessive.

  4. Blood Type There are multiple genotypes: Phenotype A = Genotype AA, Ao Phenotype B = Genotype BB. Bo Phenotype AB = Genotype AB Phenotype O = Genotype oo

  5. Blood Type • Punnett Squares are worked the same way as before: • Cross AA with Bo A A B AB AB What are the possible Genotypes? Phenotypes? o Ao Ao

  6. Sex-linked traits • Sex is determined by the X and Y chromosomes. XX is female XY is male

  7. Sex-linked traits Genotype uses Xs and Ys. Female = XX Male = XY

  8. Sex-linked traits Cross a male and a female. What are the frequencies of: female offspring? Male offspring? X X XX X XX Y XY XY

  9. Sex-linked traits Some genes are only found on the X or the Y chromosome. These traits are SEX-LINKED. Common examples include Hemophilia and colr-blindness.

  10. Sex-linked traits The alleles you are looking at are written as superscripts on the X and Y chromosomes. XBXB XBY

  11. Sex-linked traits Example: The gene for colorblindess is only found on the X chromosome B= normal vision; b= colorblind Female with normal vision: XBXb or XBXB Female with colorblindness: XbXb Male with normal vision: XBY Male with colorblindness: XbY

  12. Sex-linked traits Punnett squares work the same way, use X and Y in the genotypes. XB Xb Cross a heterozygous normal vision female with a normal vision male. Genotypes? Phenotypes? XB XBXB XBXb XBY Y XbY

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