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Principle of Inheritance and Variation Part 4 (in Hindi)
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All important topics releated to this chapter.

Shivam Sharma
Learning and teaching Biology, pursuing medical studies at TU.

U
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mam ur voice is a bit low
  1. PRINCIPLES OF INHERITANCE AND VARIATION


  2. MUTATION Phenotypic variation occurs due to change in gene or DNA sequence is called mutation. The organism that undergoes mutation is mutant. Phenomenon which result in alternation of DNA sequence & result in change in genotype & phenotype Loss (deletion) or gain (insertion/duplication) of a segment of DNA results in alteration in chromosomes- abnormalities/ aberrations- Chromosomal aberrations . . 1. 2. Gene Mutations: The mutation takes place due to change ina single base pair of DNA is called gene mutation or point mutation. E.g. sickle cell anemia. Frame shift mutations: Deletion or insertions of base pairs of DNA is called frame shift mutations. 3.


  3. PEDIGREE ANALYSIS: Male female The study of inheritance of genetic traits in several sex unspecified enerations of a family is called affected individuals the pedigree analysis. Pedigree study- strong tool of matin human genetics to trace inheritance of specific trait/ abnormality/ diseases Pedigree analysis of inheritance of a traits is represented in family tree It helps in genetic counseling to avoid genetic disorders. mating between relatives (consanguineous mating) parents above and children below inorder of birth-left to right) parents with male child affected with disease Identical twins an Non-identical twins


  4. GENETIC DISORDERS . Genetic disorders grouped into two categories - 1. Mendelian disorder 2. Chromosomal disorder MENDELIAN DISORDERS . Mendelian disorders are mainly determined by alteration or mutation in the single gene . It obey the principle of Mendelian inheritance (principles of inheritance) during transmission from one generation to other. Mendelian disorder- traced in family by pedigree analysis E.g. Haemophilia, Colorblindness, Cystic fibrosis, Sickle cell anemia, Phenylketonuria, Thalesemia etc. Dominant or recessive- pedigree analysis Trait may linked to sex chromosome, Eg. Haemophilia X-linked recessive trait- transmitted from carrier female to male progeny .


  5. GENETIC DISORDERS . Genetic disorders grouped into two categories - 1. Mendelian disorder 2. Chromosomal disorder MENDELIAN DISORDERS . Mendelian disorders are mainly determined by alteration or mutation in the single gene . It obey the principle of Mendelian inheritance (principles of inheritance) during transmission from one generation to other. Mendelian disorder- traced in family by pedigree analysis E.g. Haemophilia, Colorblindness, Cystic fibrosis, Sickle cell anemia, Phenylketonuria, Thalesemia etc. Dominant or recessive- pedigree analysis Trait may linked to sex chromosome, Eg. Haemophilia X-linked recessive trait- transmitted from carrier female to male progeny .


  6. Hemophilia: It is a sex linked recessive disease. . The defective individual continuously bleed to a simple cut. The gene for hemophilia is located on X chromosome. In this disease a single protein that is a part of cascade of proteins that involved in the clotting of blood is affected. The diseases transmitted from unaffected carrier female to some of the male progeny Heterozygous female (carrier)- transmit to sons . . Female being hemophilic is rare- Mother should be carrier & father Haemophilic


  7. XY Father with Mother unaffected by hemophilia hemophilia Possible outcomes for each pregnancy XY No Sons will have Hemophilia All Daughters will be Carriers


  8. XY Father unaffected Mother carier by hemophilia o hmophilia Possible outcomes for each pregnancy XY 25% Son without Hemophilia XY 25% Son with Hemophilia 25% Daughter Carrier of hemohpilia 25% Daughter not a Carrier


  9. XY Father with hemophilia Mother carrier of hemophilia Possible outcomes for each pregnancy XY 25% Son with Hemophilia XY 25% Son without Hemophilia 25% Daughter with Hemophilia 25% Daughter Carrier of hemohpilia


  10. SICKLE CELL ANEMIA Start of coding sequence DNA CAC GTG GAC TGA GGA CTC CTC sequence GTG CAC CTG ACT CCT GAG GA G Amino acid Glutamic Glutamic Valine Histidine Leucine Threonine Proline acid acid Normal Normal red blood cells DNA CAC GTG GAC TGA GGA CAC CTC sequence GTG CAC CTG ACT CCT GTG GAG Amino acld sequence Valine Glutamic HistidineLoucine Threonine ProliValine Mutant Sickled red blood cells The change in amino acid sequence causes hemoglobin molecules to crystallize when oxygen levels in the blood are low. As a result, red blood cells sickle and get stuck in small blood vessels.


  11. Father (with trait) Mother (normal) Father (with trait) Mother (with trait) Children SC SC Children T T SCN Father (with sickle cell anemia) Mother (with sickle cell anenia) Children SC SC SC SC SC SC Father (with sickle cell anemia) Father (with sickle cell anemia) T T T T Mother (normal) Mother (with trait) T T SC SC Children Children T- Trait N- Normal SC- Sickle cell


  12. CHROMOSOMAL DISORDER . Caused due to absence or excess or abnormal arrangement of one or more chromosome. Causes: 1. Failure of segregation of chromatids- cell division cycle- gain or loss chromosome- Aneuploidy, Eg.- Down's syndrome (Extra copy of 21 chromosome)- Trisomy, Turner's syndrome (loss of an X chromosome in female)- Monosomy Failure of cytokinesis after telophase- increase in whole set chromosomes-Polyploidy, seen in plants 2.


  13. TURNER'S SYNDROME Absence of one of X- chromosome, Monosomy Karyotype- 45, X0 Females-sterile, ovaries are rudimentary, lack of secondary sexual character ' 12 . TIS CAUSED BY A TURNER YNDROME ONLYPROBLEM WITH ONE AFFECTS GIRLS OF THEX CHROMOSOMES


  14. Turner syndrome Klinefelter syndrome 45,Xo 47,XXYE 21 22 x x 21 22 XXY


  15. hank