Principles of Inheritance and Variation
- Gregor johann mendel is called as “Father of Genetics”, as he was the first to demonstrate the mechanism of Inheritance.
- He carried out experiments using Pisum sativum (Garden pea) for 7 years as it had 7 contrasting characters with 2n = 14.
- Selection of preline parents, Hybridisotion, selfing of first filial generation and calculation using pannett square were the four steps involved in his experiments.
- Cross pollination of flowers involves steps such as Emasculation, Bagging, dusting and tagging.
- Mendel’s monohybrid cross (cross involving single pair of contrasting characters) yield a phenotypic ratio of 3 : 1 [Tall : dwarf] and a genotypic ratio of 1 : 2 : 1. [TT : Tt : tt]
- By performing a cross experiment with tall (TT) and dwarf plant (tt)
- From monohybrid cross, Mendel could frame 2 important laws of inheritance
(i) Law of segregation [alleles get segregated into gametes individually]
(ii) Law of Dominance [In order to express a dominant character, at least one of the alleles should be dominant; both the alleles should be recessive to express a recessive character]
- Dihybrid cross (cross involving 2 pairs of contrasting characters – seed colour and seed shape) between round yellow(RRYY) and wrinkled(rryy) green plants yield a phenotypic ratio of 9 : 3 : 3 : 1 [Round – yellow : Round – green; wrinkled yellow; wrinkled green].
- The above cross shows that the factors of 2 characters assort independent that leads to formation of independent assortment factors, by which he could frame the third law [law of independent assortment].
Part-1: Watch this video for the topic from 0:26 to 16:45
Part-2: Watch this video for the topic from 0:26 to 13:47
Part-3: Watch this video for the topic from 0:11 to 12:38
Part-4: Watch this video for the topic from 0:26 to 12:17
Part-5: Watch this video for the topic from 0:10 to 6:38
Part-6: Watch this video for the topic from 0:13 to 13:38
Part-7: Watch this video for the topic from 0:10 to 8:46
Part-8: Watch this video for the topic from 0:18 to 14:50
Part-9: Watch this video for the topic from 0:09 to 9:40
Part-10: Watch this video for the topic from 0:10 to 8:27
Part-11: Watch this video for the topic from 0:10 to 6:03
Part-12: Watch this video for the topic from 0:10 to 6:31
Disclaimer: Compete.etutor.co may from time to time provide links to third party Internet sites under their respective fair use policy and it may from time to time provide materials from such third parties on this website. These third party sites and any third party materials are provided for viewers convenience and for non-commercial educational purpose only. Compete does not operate or control in any respect any information, products or services available on these third party sites. Compete.etutor.co makes no representations whatsoever concerning the content of these sites and the fact that compete.etutor.co has provided a link to such sites is NOT an endorsement, authorization, sponsorship, or affiliation by compete.etutor.co with respect to such sites, its services, the products displayed, its owners, or its providers.