Chapter 15:CHROMOSOMES

  Introduction


The male has two chromosomes X and Y, the female has only X chromosomes. During reproduction if X and X chromosome come together than the zygote shall develop into female if X and Y chromosome fuse, then zygote shall develop into male.

Gender Determination


The sex of the offspring depends on whether he inherits X chromosome from father making it XX pair [female child] or Y chromosome from father making it XY pair [male child].

Facts about Blood Group

Also if one parent has blood group A and second B, then offspring may get AB.


If one parent = A, second parent =O, then A;

If one parent = B, second parent =O, then offspring may get B;

If one parent = O, second parent =O, then offspring may get O.

If one parent = AB, second parent =A/B/O, then offspring may get AB;

Chromosomal disorders

There are 23 chromosomes, 22 autosomes and 1 pair of sex chromosomes.


Genetic disorders are Hemophilia [sex chromosome linked passed from mother to son], Cystic fibrosis, Sickle-cell anemia [autosomal – can be passed from any parent to offspring], Color blindness [sex chromosome linked passed from mother to son, in rare cases to daughters if father is color blind and mother is a carrier], Phenylketonuria [autosomal], Thalassemia [ autosomal ] due to defective genes.

Miscellaneous


Allergic person release IgE antibody and the blood cells release histamines these cause allergic reactions.

Official YouTube Channel of UPSCFEVER - #1

Quiz

Score more than 80% marks and move ahead else stay back and read again!


















5