Role of sex linkage... biology homework?

Question

Discuss the role of sex linkage in the inheritance of genetic disorders...

Answer 1

The human genome consists of 23 chromosomes (22 autosomes and 1 set of sex chromosomes). Females have two X chromosomes and males have one X and one Y chromosome. The Y chromosome is shorter than the X chromosome. When certain genes on the X chromosome are inherited by males, they may be the only copy and thus when there's a mutation, you will see the recessive phenotype. When females inherit the X chromosome with the mutated gene, they also have another X chromosome with a 'normal' copy so that you will not see the recessive phenotype. The best example is color blindness which affects males more frequently than females.

Answer 2

Females can have hemophilia, but because hemophilia is carried on the X chromosomes and because males only have one X chromosome and one Y chromosome, if they have the hemophilia gene, they definitely have the disease and males can not be carriers. So if males have the genotype(h represents hemophilia and H presents healthy): XhY is for hemophiliac male and XHY represents healthy male. Females can be carriers becuase they have two X chromosomes and if they carry one healthy allele and one hemophiliac gene, this means that the female is a carrier. Here are some genotypes: (H=healthy, h=hemophilia) XHXh- Carrier female XHXH- Healthy female XhXh-Hemophiliac female Child of carrier mother and healthy father Lets make a Punnett shape Alleles of father XR Y Alleles XR XRXR XRY of Mother Xr XRXr XrY 25% Healthy Female XRXR 25% Hemophiliac male XrY 25% Carrier female XRXr 25% Healthy male XRY Most hemophiliacs are male because males can be healthy or hemophiliac. But females can be carriers,healthy or hemophiliac. So out of 3 females have only 1 that they are hemophiliac but for males they are 1/2 healthy and 1/2 hemophiliac so there are more male hemophiliacs.

Answer 3

Many genetic disease-causing genes are located on the X chromosomes. Women carry two Xs while men only have one. Thus, many genetic diseases hit men more severely than women.

Answer 4

The sex linked disorders are due to carrier mother or affected father. It is not directly transfered from father to child but it is cris-cross