Genetics-Important Points

  1.  The term ‘genetics’ was coined by- Bateson (1906).
  2.  Theory of germplasm was introduced by- August Weisman.
  3.  Mendel studied the inheritance of seven different pairs of contrasting characters.
  4.  % of homozygous offsprings in F2 generation of monohybrid cross is – 50
  5.  The terms ‘genotype’ and ‘phenotype’ coined by- Johanssen
  6.  Test to assess whether the individuals are showing dominant character due to
    homo or heterozygosity- Test cross
  7.  Universally accepted Mendel’s law is- Law of Segregation
  8.  The term ‘heterosis’ was coined by- Shull (1910)
  9.  Genes that influence more than one phenotype trait is called –Pleiotropic genes.
  10. Phenotypic ratio n incomplete dominance is – 1:2:1Genetics
  11.  Dominance involves intragenic gene suppression while epistasis involve
    intergenic suppression.
  12. ‘Yellow’ in mice is an example of- dominant lethal condition
  13.  Genotype that is a carrier for sickle cell anemia is – HbA/HbS
  14.  Expression of ancestral traits is termed as – Atavism.
  15.  Qualitative characters like coat color, blood group etc. shows discontinuous
    variation, where as quantitative traits like height, weight etc. shows continuous
    variations.· Alternative form of a normal gene is called- Allele
  16. Coat color in rabbits is an example of- Multiple allellism.
  17.  Number of linkage groups in an orgainsim is equal to no: of chromosome pairs.
  18.  Theory of linkage and concept of sex linked inheritance was proposed by-
    Thomas Hunt Morgan
  19.  Rediscoverer’s of Mendelian genetics was- Tschermack, Correns and Devries.
  20.  Complete linkage is seen in – Male Drosophila Genetics
  21. Sex-linked genes for hemophilia and colorblindness in man are examples of Incomplete linkage
  22. Strength of linkage is inversely proportional to the distance between the genes and the strength is reduced by temperature and X-rays
  23. Crossing over occurs between non-sister chromatids of homologous pairs of chromosomes.
  24. Chances of crossing over more if genes are located- farthest
  25.  ‘Crossing over’ takes place at the tetrad stage of meosis.
  26.  Cell division characterized by splitting of nucleus followed by that of cytoplasm is called – Amitosis.
  27.  Spindle formation inhibition and arresting the cells in metaphase are done bycolchicine.
  28. Examples of mitotic poison- Colchicine, Ribonuclease and Mustard gas.
  29. During meosis, pairing of chromosomes occur at- Zygotene stage
  30. From one spermatocyte 4 haploid spermatids are formed where as one oocyte forms single ovum.
  31. The term ‘Chromosome’ was coined by – Waldeyer
  32.  Chromosomal basis of heredity was proposed by- Walter. S. Sutton.
  33.  Chromosome with centromere in terminal position is called– Acrocentric.
  34.  Chromosomes with subterminal centromere is called- Telocentric (J-shaped)
  35.  Interphase chromosomes which are large and visible with naked eye are called- Polytene chromosomes.
  36. Cri-du-chat’ or ‘Cat cry syndrome’ is caused by deletion in the short arm of 5th chromosome
  37. Interchange of chromosome segments in non-homologous chromosomes is called-Translocation
  38.  The method devised by Muller for detecting X-linked mutations in Drosophila is           CIB method.
  39. Classical experiments on Neurospora crassa was performed by- Beadle and Tatum.
  40.  Substitution of a purine by a pyrimidine is called- Transversion
  41. Changes that involve replacement of one purine in a polynucleotide chain by another purine is called- Transitions
  42.  Alkylating agents capable of causing mutations are- Ethyl methane sulphonate and Methyl methane sulphonate.
  43. Mutations caused by addition or deletion of nitrogenous based in the DNA or mRNA are known as- Frame shift mutation.
  44. In interphase, nucleus of cells in females a dark stained chromatin mass is observed called- Barr body.

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