The genes associated with different traits are present on the chromosomes. The genes present on sex chromosomes (X and Y chromosomes) are associated with controlling sex-linked traits.
The patterns of inheritance of traits for X linked and Y linked genes are different compared to autosomal genes. Also, X linked and Y linked traits are inherited differently from each other. So, it is important to understand the difference between X linked and Y linked inheritance.
Inheritance
It is the transfer of genetic information from parents to offspring. The genes present on the chromosomes store all the genetic information.
X linked inheritance
X linked inheritance is the transfer of traits controlled by genes present on X chromosomes. X chromosomes are present in both males and females, so both parents are involved in X linked inheritance.
X linked inheritance can be dominant and recessive. X linked dominant inheritance is linked with dominant genes and only one copy of that gene is enough to express the associated trait.
In the case of X linked recessive inheritance, the trait is only expressed when both alleles of the genes are recessive. The X lined recessive traits are expressed in males because they only receive one X chromosome. But expressed in females only when the female is homozygous for that particular trait.
Any change or mutation in the X chromosome of an affected father can be transferred to the daughter but none of the sons will be affected as the son receive the X chromosome from the mother.
Examples of X linked inheritance
Examples of X linked recessive disorder includes red-green color blindness and hemophilia A. While Rett syndrome is an example of X linked dominant disorder. It is a genetic disorder observed in girls in which brain development is affected which results in mental and physical disability.
Video lesson on X linked dominant inheritance
Y linked inheritance
Y linked inheritance is the transfer of traits controlled by genes present on Y chromosomes. Y chromosomes are only present in males so only the father is involved in Y linked inheritance.
Y linked inheritance is neither dominant nor recessive as males receive only one Y chromosome. Moreover, any change or mutation in the genes on the Y chromosome can be transferred from the affected father to the son.
As only sons receive the Y chromosome, Y linked associated disorders can only be observed in sons and not in daughters. That is why Y linked disorders are very rare.
Examples of Y linked inheritance
Maleness and hairy ears are examples of Y linked inheritance.
Video lesson on Y linked inheritance
Difference between X linked and Y linked inheritance
The main difference between X linked and Y linked inheritance are listed in the table.
|
X Linked Inheritance |
Y Linked Inheritance |
|
Traits controlled by genes present on X chromosomes |
Traits controlled by genes present on Y chromosomes |
|
Present in both females and males |
Present in males only |
|
May be dominant and recessive |
No dominant and recessive |
|
Daughters of an affected father but none of his sons are
affected. |
All sons of an affected father are affected by Y linked
traits. |
|
Recessive X linked traits are expressed in males and homozygous
female |
Y link traits are not expressed in females |
|
Example: Red-green color blindness and hemophilia A |
Example: Maleness and hairy ears |
Figure of difference between X linked and Y linked inheritance
Video lesson on difference between X linked and Y linked inheritance
Some questions and answers
1. Why is Y linked trait only present in males?
A. As only males or sons receive the Y chromosome from their father, so Y linked associated traits can only be observed in males and not in females.
2. What is an example of an X linked dominant disease?
A. Rett syndrome is an example of X linked dominant disorder. It is a genetic disorder observed in girls in which brain development is affected which results in mental and physical disability.
3. What do you mean by X-linked inheritance?
A. X linked inheritance is the transfer of traits controlled by genes present on X chromosomes. X chromosomes are present in both males and females, so both parents are involved in X linked inheritance.
4. What is Y linked inheritance?
A. Y linked inheritance is the transfer of traits controlled by genes present on Y chromosomes. Y chromosomes are only present in males so only the father is involved in Y linked inheritance.
5. What genetic traits are Y linked to?A. Maleness and hairy ears are examples of Y linked inheritance.
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