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PRESENTATION ON

PRESENTATION ON . SEX LINKED INHERITANCE. SEX…???. Type of division on individual i.e. male and female is sex. Sex is determine by the chromosome. Sex defined chromosomes are:- XX and XY. XX indicates female where as XY indicates male. LINKED..???. LINKED word simply mean connection.

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PRESENTATION ON

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  1. PRESENTATION ON SEX LINKED INHERITANCE

  2. SEX…??? • Type of division on individual i.e. male and female is sex. • Sex is determine by the chromosome. • Sex defined chromosomes are:- XX and XY. • XX indicates female where as XY indicates male.

  3. LINKED..??? • LINKED word simply mean connection. • Linked came from word linkage. • Gene which are present in a chromosome are linked gene and the inheritance pattern of these gene are called linkage. • The term linkage was given by T.H MORGAN in 1910 while working in DorsophillaMelanogaster.

  4. SEX-LINKED INHERITANCE • Genes located in X-chromosome are called sex-linked genes and the pattern of inheritance is called sex-linked inheritance. • Genes are usually inheritance along with X-chromosome. The Y-chromosome is genetically inert or empty, it doesn’t carry genes due to its small size. Genes present in the Y-chromosomes are holandric genes. Greek holos=whole and Andros=man. • SEX linked genes were first reported by an American zoologist THOMAS HUNT MORGAN in 1910 while working on the inheritance of eye colour in DORSOPHILLA MILANOGASTER.

  5. CROSS OF DORSOPLILLA MILANOGASTER

  6. SEX-LINKED INHERITANCE IN MAN • There are two well known examples of recessive sex-linked traits in man: • COLOUR BLINDNESS • HAEMOPHILIA • The genes for both the diseases are recessive and X-linked.

  7. COLOUR BLINDNESS Mensuffering from colour blindness cannot distinguish between red and green colour. There is a gene on the X-chromosome which is necessary for the formation of colour sensitive cells in retina for the distinction of red and green colour. The colour blind men carry a recessive gene for colour blindness on X-chromosome in the XY set of germ cells. This X-linked recessive gene is able to express itself in males due to the absence of its allelic genes in the Y-chromosome. The recessive gene i.e. present in the non-homologous part of the x-chromosome. It is estimated that about 4% of all human males and less than 1% of all human females are suffering from colour blindness.

  8. Colour Blindness: No sense of vision for red and green colour.

  9. HAEMOPHILIAorbleeders diseases or royal disease Haemophilia is a disease in which blood does not clot properly. It is very rare disease found only in a few humans. The person which contain the recessive gene for haemophilia lacks in normal clotting substance i.e. antihemophilicglobutian in blood. Such person will bleed continuously from a small cut. As a result, minute cuts lead to prolonged bleeding leading to death. Since gene is recessive, a carrier woman i.e. heterozygous passes on the gene to 50% of her sons even when the father is normal. It also follows the criss-cross pattern of inheritance, i.e. a male transmit his sex-linked traits to his grandchildren via his daughters. Haemophilia is well know in royal families of Europe. The gene probably appeared as a mutant in Queen Victoria of England , who must be heterozygous i.e. carrier. No haemoplilic is known in her ancestry; hence, it is concluded that her haemoplilic alleles arose from mutant gametes. She was a carrier but nonsuffered. Victoria’s son Leopold died of haemophilia at the age of 31 and three of her daughter were carrier of the dieses and transmitted haemophilia to their children and grandchildren to several generation. Due to intermarriages, several royal families of Europe were affected by haemophilia . the genes of haemophilla is recessive and present in the x-chromosome . Thus , a single gene produces the disease in males while two genes will produce the disease in females.

  10. Hemophilia :

  11. THANK YOUU… PREPARED BY:- SONU TIMSINA CLASS: 12 D NOBEL ACADEMY.

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