Sex linked inheritance

Full Answer Section

X inactivation is a process that occurs in female mammals to ensure that only one X chromosome is active in each cell. This is necessary because having two active X chromosomes would lead to an overexpression of genes on the X chromosome.

X inactivation is random, so in about half of the cells in a female's body, the paternal X chromosome is inactivated, and in the other half, the maternal X chromosome is inactivated. The inactive X chromosome is called the Barr body.

The purpose of X inactivation is to prevent an overexpression of genes on the X chromosome. This is important because the X chromosome contains many genes that are essential for normal development.

Heterozygous and homozygous are terms used to describe the genotype of an individual. The genotype is the genetic makeup of an individual, and it is determined by the alleles that they inherit from their parents.

An allele is a variant of a gene. For example, the gene for eye color has two alleles: brown and blue. A person who is heterozygous for eye color has one allele for brown eyes and one allele for blue eyes. A person who is homozygous for eye color has two of the same alleles, either brown or blue.

In the case of eye color, a person who is heterozygous for eye color will have brown eyes, but they may have a blue-eyed sibling. This is because the blue allele is recessive, which means that it is only expressed when two copies of the allele are present.

Here is another example. The gene for sickle cell anemia is also a recessive gene. A person who is homozygous for sickle cell anemia will have sickle cell anemia, but a person who is heterozygous for sickle cell anemia will not have sickle cell anemia. They will be carriers of the sickle cell anemia gene, but they will not have the disease.

I hope this helps!

Sample Answer

Sex-linked inheritance is a mode of inheritance in which a gene is located on a sex chromosome. In humans, the sex chromosomes are the X chromosome and the Y chromosome. Females have two X chromosomes, while males have one X chromosome and one Y chromosome.

X-linked genes are more common in males than females because males only have one copy of the X chromosome, while females have two copies. If a male inherits a recessive X-linked allele, he will express the trait associated with that allele, even if the allele is not dominant. In contrast, a female must inherit two copies of the recessive X-linked allele in order to express the trait.