Name the alternative forms of a gene.
Important Points to Remember in Chapter -1 - Genetics from Dr. K.K. Aggarwal A New Approach to Biology Solutions
1. Heredity:
(i) The term genetics was coined by Bateson.
(ii) Transmission of herditary characters from parents to offspring is called heredity.
(iii) The study of heredity and variation is called genetics.
(iv) Gregor Johann Mendel is called father of genetics.
2. Mendel's experiment:
(i) Mendel performed hybridization experiments on garden pea (Pisum sativum), on the basis of results of these expeliments, Mendel formulated the laws of inheritance, called as Mendelism.
(ii) Hugo de Vries, Carl Correns and Erich Von Tschermak rediscovered the Mendel's laws of segregation.
(iii) Mendel studied the inheritance of one character at a time.
(iv) When two alleles of a gene are similiar, they are called as homozygous and if they are dissimilar, then they are called as heterozygous.
(v) Offspring obtained from parents is F1 generation and obtained from F1 generation is called F2 generation.
(vi) A character which expresses itself in F1 generation is called dominant character and which does not express itself in F1 generation is called recessive character.
(vii) The type of cross in which F1 generation is crossed with recessive parent, called as test cross.
(viii) The type of cross in which F1 generation is crossed with any one of two parents, called as back cross.
(ix) According to Mendel's law of segregation or law of purity of gametes, at the time of gamete formation alleles segregate and each gamete carries one alleles for each character.
(x) According to Mendel's law of independent assortment, two or more than two gene pairs behave independently of each other while living together.
(xi) According to Mendel, phenotypic ratio and genotypic ratio obtained from monohybrid cross is 3 : 1 and 1 : 2 : 1 respectively.
(xii) Phenotypic ratio obtained from generation of dihybrid cross is 9 : 3 : 3 : 1 and genotypic ratio is 1 : 2 : 2 : 4 : 1 : 2 : 1 : 2 : 1.
(xiii) Good characters of different genera can be brought in a single genus by hybridization.
(xiv) With the help of mendel's laws disease resistant and high yielding varieties of crops can be developed.
(xv) Mendel's laws confirm the concept of gene.
(xvi) A branch of science Eugenics related with the improvement of human race is based on Mendel's laws.
