Part 4: Sex-Linked Inheritance—Predicting Color Blindness in Offspring
Recall that females have two X chromosomes: one from the mother and one from the father. Males have one X chromosome and one Y chromosome; the X chromosome comes from the mother, and the Y chromosome comes from the father. Traits associated with genes located on the sex chromosomes are called sex-linked traits.
Individuals with the sex-linked condition called red-green color blindness do not perceive the colors red and green. Red-green color blindness is caused by the recessive allele c and is carried on the X chromosome. The dominant allele for normal color vision is C. When an X chromosome contains the dominant allele, the allele is written as XC. When an X chromosome contains the recessive allele, the allele is written as Xc.
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1. What is the genotype of a male with red-green color blindness?
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2. What is the genotype of a female who is not color-blind but is a carrier of red-green color blindness?
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3. Even though red-green color blindness is a recessive trait, can a female have red-green color blindness? Explain.
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4. A man who is color-blind marries a woman who is not color-blind and is not a carrier of the allele for color blindness. Create a Punnett square to predict the possible genotypes of their children.
Answer:
Part 4 Punnett Square

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5. Will all of the female children be carriers of the color-blind allele, or will none be carriers? Explain.
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6. Will all of the male children be color-blind, or will none be color-blind? Explain.
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1.cc
2.Cc
3.Yes a female can have color blindness, but it is far less likely than a male , as both her x chromosomes would have to have the recessive c .
4.
5.All would be carriers, as they would each get Cc , because those are the only inheritable genotypes.
6.The male children would all be non colorblind , because they inherit a y from their dad to be male , and the mom isn't a carrier , so the only x they inherit is a C.

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sofiaplillo sofiaplillo · Answer 2 · 2019-12-28T03:29:34+01:00

Answer and explanation.

1. The genotype of a male with red-green color blindness is XcY.

2. The genotype of a female who is not color-blind but is a carrier is XcXC. She carries the color-blind allele but is not dominat, so she is not affected by it.

3. Yes, a female can have red-green color blindness, if her two X chromosomes are cX (recessive), she will have red-green color blindness. In other words, if the two X chromosomes carry the allele for color-blindness she will be affected by it.

4. Possible genotypes are Cc, CC, Cc, and CC. or as it is in the Punnet square XcXc, XcY, XCXc, XCY.

║ Xc ║ Y

Xc ║ XcXc ║ XcY

XC ║ XCXc║ XCY

5. The female children will be carriers of the color-blind allele becaus one of her two X chromosomes, has the recessive allele for color-blind while the other X chromosome has not the allele for color-blindness.

6. None of the male children will be color-blindness because the allele for color-blindness is carried by the X chromosome of the father and they inherit the X chromosome from the mother, who is color-blind free.