HEREDITY

Heredity is the transmission of characters from one generation to another. In sexually reproducing organism there is the need of two parents to undergo reproduction, of which one is male and other is female. The gametes produced by the male are called the sperms and the gametes produced by the female are called the egg. These gametes have in them the DNA which is the genetic material. Fusion of the two gametes ie. egg and sperm leads to the formation of a zygote. So the zygote has in them the characters coming from two parents, which ultimately leads to the formation of an organism. As the organism is produced with the help of two parents, so there is the occurrence of variation. Therefore in heredity we find two things one is transmission of characters and other is the variation.

In Asexually reproducing organism, only one parent is sufficient to give rise to an organism , so genetics constituents of a parent and of the next generation is exactly same and therefore we are not finding variation in Asexually reproducing organism. Here we are finding a terminology called DNA copying, which means DNA of the parent is doubled and transmitted to the next generation.

DNA is the genetic material, it is the information source for making proteins in the cell. A section of DNA that provides information for a protein is called Gene. Proteins here are enzymes. If the enzymes that are produced work efficiently than lot of hormones are produced which play a role in shaping a character and its transmission.

Gregor Johan Mendel is known as the father of Genetics. Mendel did experiments on garden pea /Pea plant (Pisum sativum) as the plant was easy to grow, large number of breeding verities was found. Mendel became successful  as the pea plant had a very short life cycle and he was able to do both cross fertilization and self fertilization. He took seven pairs of contrasting characters to perform  Monohybrid , Dihybrid  etc. experiments.

We have 23 pairs of Chromosomes, out of which 22 pairs are called autosomes and 1 pair is called Sex chromosome. Autosome pairs are same for both male and female but they differ in Sex chromosomes. Male has XY sex chromosomes and Female has XX Chromosomes.

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