26. Chromosome and Sex Determination (क्रोमोजोम र लिङ्ग निर्धारण)

DNA and Chromosome:

  • DNA is the double stranded helix structure composed with the series of four types of nitrogen bases (Adenine-Thyamine, Cytosine- Guanine) that constitutes the genetic information or series of genes that controls the characteristic of living beings. They are presented in the chromosome. They are responsible for controlling characteristics and heredity.
  • DNA constitutes the Chromosome.
  • Chromosome are the thick and short ribbon like structure formed during the cell division process and containing the chromatids that are formed from the thin and thread like structures called chromatin reticulum. They are most important base of living organisms that contains and control the base, characteristics and heredity in living organisms.

Chromosome Types:

  • Metacentric
  • sub-metacentric
  • acrocentric and
  • telocentric

classification-of-chromosome-position-centromere

human chromosome

Chromosomal disorders:

The state of disorder in chromosome due to addition or subtraction of chromosome is called chromosomal disorder. The chromosomal disorder creates a physical and biological abnormalities in human.

Some of the chromosomal disorders are discussed below.

Down’s syndrome:

  • A Chromosomal disorder due to trisomy in the 21st pair of chromosome is called the down’s syndrome.
  • Down’s syndrome include mental retardation, short and broad neck, creezed armpits etc.

down's syndrome

Kleineifelter’s syndrome :

  • A chromosomal disorder formed due to abnormal XX eggs and normal Y sperm or normal X with abnormal XY sperm cells. So this disorder carries 47 with XXY chromosome.
  • Kleineifelter’s syndrom cause abnormal sterile male with underdeveloped testes, female like body hair, pitched voice and enlarged breasts.

kleineifelter

Turner’s syndrome:

  • A chromosomal disorder in which an individual has 45 chromosome with XO.
  • Turner’s syndrome cause abnormal sterile female with poorly developed ovaries, underdeveloped breasts, small uterus etc.

45,X turners

  • Sex determination:

Human have 23 pairs of chromosome. 22 pair are called autosome while 1 pair is the sex chromosome that determines the sex of the person.

Female have XX chromosome and male have XY chromosome. The male and female gamete consists of 23 chromosome called the haploid chromosome.

During the fertilization process, The fusion of X chromosome from mother and Y chromosome from father causes the birth of a male baby while the fusion of X from mother and X from father causes to the birth of a female baby.

female gamete male gamete X X by X Y

XX (female) XY(male) XX (female) XY(male)

  • Number of chromosome in some animals and plants:
  1. Gorilla: 48 (24 pair)
  2. Human : 46 (23 pair)
  3. Mouse: 40 (20 pair)
  4. Frog: 26 (13 pair)
  5. Butterfly: 12 (6 pair)
  6. Fungi : 2 (1 pair)
  7. Cucumber: 14 (7 pair)
  8. Barley: 14 (7 pair)
  9. Aloevera: 14 (7 pair)
  10. Pea: 14 (7 pair)
  11. Onion: 16 (8 pair)
  12. Maize: 20 (10 pair)
  13. Rice: 24 (12 pair)
  14. Potato: 48 (24 pair)
  15. Pinus: 24 (12 pair)
  16. Sugarcane: 80 (40 pair)
  • sex Linked Diseases:

Those diseases that exist in specific gender only are sex linked diseases. Example, Hemophilia in male, Breast Cancer in female, Prostate Cancer in male, Baldness in male etc.

  • Hemophilia:

The sex linked disease caused by the chromosomal disorder in male X chromosome transferred from mother. It causes the blood not to clot. So the bleeding is not controlled.