1. What is the genotype of a male with red-green color blindness?

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?

1 Answer
Jan 22, 2018

The genotype of male with red-green color blindness is XY, X chromosome possessing recessive allele of gene responsible for differentiating red-green color.


Color blindness is sex-linked trait and its inheritance follows criss-cross pattern. Dominant gene of allelomorpihc pair enables a person to differentiate between red and green color.

The genotype of male and female are different for the pair of sex chromosomes. Male is hetero-zygous (XY) and female is homo-zygous (XX). The gene controlling this trait is present on X chromosome.

Color blindness is more common in males than in females. Female will be color blind only if it is homozygous for recessive allele causing color blindness, the defective allele contributed by both parents.

Female with heterozygous genotype , having one recessive allele will be carrier of color blindness, but will not be color blind.

Male becomes color blind if recessive defective allele is contributed by mother only as it inherits Y chromosome from the father.