Which of the following is true about color blindness

All of the following are true of color blindness, EXCEPT it can be passed from a color-blind mother to her son. it only rarel


Ans it only occurs in females is a wrong statement . Colorblindness is a sex (X)linked recessive trait . Means the defective gene will be on X chromosome . So in females they carry two X chromosomes while males have XY chromosomes . Females inherit one X chr from father and one from mother . While males inherit X chr from mother and Y chr from father. For a female to be colorblind both the X chromosomes need to carry the defective allele. So if X* is the defective chromome. Then for a female to be colorblind the genotype has to be X*X* . Becuase if it is X*X since the condition is recessive the normal X chr dominates and supresses the effects of the defective Chromome. So the female becomes a carrier. That is she inherited the disorder but is not colirblind . For a female to be coloirblind ,she must inherit one defective X* chr from father and one X* from mother . But in males only one X chr is present and since the disorder is X linked ,the condition gets expressed . So males are more commonly affected . But females can also be affected ,but the probability is lesser than males .

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