GENETICS AND EVOLUTION
GENETIC BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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fathers can only pass the allele for hemophilia to their sons
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mothers cannot pass the allele for hemophilia to their daughters
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the allele for hemophilia is dominant and located on the Y chromosome
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the allele for hemophilia is recessive and located on the X chromosome
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Detailed explanation-1: -Because male offspring only inherit one X chromosome, haemophilia is more common among them. Both an X and a Y chromosome are found in males, whereas females have two X chromosomes.
Detailed explanation-2: -Since males have only a single copy of any gene located on the X chromosome, they cannot offset damage to that gene with an additional copy as can females. Consequently, X-linked disorders such as Hemophilia A are far more common in males.
Detailed explanation-3: -The abnormal gene responsible for hemophilia is carried on the X chromosome. Males have one X chromosome and one Y chromosome. In a male, the presence of the abnormal gene results in the deficiency or absence of factor VIII or factor IX, as there is no protective X to make factor VIII or IX.
Detailed explanation-4: -Hemophilia is an X-linked recessive hereditary disorder that classically affects males due to the presence of only one X chromosome in males. Females are usually carriers due to the presence of counterpart X chromosome, but many times manifestations of hemophilia are seen in heterozygous carrier females.
Detailed explanation-5: -Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern . The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes . In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition.