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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 b and is carried on the X chromosome. The dominant allele for normal color vision is B. When an X chromosome contains the dominant allele, the allele is written as . When an X chromosome contains the recessive allele, the allele is written as .
(Score for Question 1: ___ of 1 points)
1. What is the genotype of a male with red-green color blindness?
Answer:
Type your answer here.
(Score for Question 2: ___ of 1 points)
2. What is the genotype of a female who is not color-blind but is a carrier of red-green color blindness?
Answer:
Type your answer here.
(Score for Question 3: ___ of 2 points)
3. Even though red-green color blindness is a recessive trait, can a female have red-green color blindness? Explain.
Answer:
Type your answer here.
(Score for Question 4: ___ of 2 points)
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:
Type your answer here.
Part 4 Punnett Square




(Score for Question 5: ___ of 1 points)
5. Will all of the female children be carriers of the color-blind allele, or will none be carriers?
Answer:
Type your answer here.
(Score for Question 6: ___ of 1 points)
6. Will all of the male children be color-blind, or will none be color-blind? Explain.
Answer:
Type your answer here.

Respuesta :

underV
1) recessive allele is b
    dominant allele is B
When an X chromosome contains the dominant allele,is written as: [tex]X^B[/tex]

2) When an X chromosome contains the recessive allele, is written as:[tex]X^b[/tex]

3)
question 1)  The genotype of a male with red-green color blindness is [tex]X^bY[/tex]
Since its a male, he has a Y chromosome and one X chromosome. If the only X he has has the recessive allele, he will express the red green color blindness. The Y doesn't have any allele associated to this colorblindness.

4)
question 2) the genotype of a female who is not color-blind but is a carrier of red-green color blindness: [tex]X^BX^b[/tex]
Since its a female, she has two X chromosomes.  If she is not colorblind is because there is the dominant allele making her see normally. But, she is a carrier, so while one X chromosomes has the dominant allele, the other has the recessive (making her carry the disease). 

5)
question 3) Yes, even though red-green color blindness is a recessive trait,  a female can still have red-green color blindness.
Since its a female, she has two X chromosomes.  For a woman to be red-green colorblind, she needs to inherit both X chromosomes with the recessive trait from the mother and the father.
 6)
question 4)
A man who is color-blind has the [tex]X^bY[/tex] genotype. He marries a woman who is not color-blind and is not a carrier of the allele, so none of her alleles is recessive. Her genotype is: [tex]X^BX^B[/tex]
Their offspring, if they are girls, they will be carriers, because they receive a normal allele from the mother but a allele with the disease from the father(
[tex]X^BX^b[/tex]) . If they are boys, they will receive a Y from the father and a normal allele from the mother, so none will suffer from colorblindness ([tex]X^BY[/tex])
7)
question 5)
all of the female children will be carriers of the color-blind allele because they receive a normal allele from the mother but a allele with the disease from the father. They will have this genotype: [tex]X^BX^b[/tex]
 8)
question 6)
None of the male children will be color-blind  because they will receive a Y chromosome from the father and a chromosome with the normal allele from the mother, so none will suffer from red-green color blindness. Their genotypes: [tex]X^BY[/tex]

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