Dr Praveen Kumar Agrawal is teaching live on Unacademy Plus
COURSE Principles of inheritance and variations Lesson 7 Inheritance of one gene and Mendel's laws Dr. Praveen Kumar Agrawal M.Sc., Ph.D., CSIR NET (JRF). SRF, GATE 21Years of Pre-medical teaching experience
UNACADEMY LIVE NOW SUBSCRIBE FOR ALL LIVE/PLUS COURSES Of ALL EDUCATORS IN PRE MED CATEGORY ONLY FOR A NOMINAL FEE Use following referral code for EXTRA 10% REBATE biologybypkagrawal-6909
Inheritance of One Gene (Mendel's Monohybrid Cross) In his classical monohybrid cross, Mendel took two pure-line (homozygous) plants and cross pollinated them One of the plants was tall (TT) while other was dwarf (tt). In F1 generation he obtained all tall plants. Tall TT tt Dwarf tGametes T t T t T t Tt Tall Tall Tall Tall
Mendel was highly surprised with the result of F1 generation. The generation did not contain any dwarf plant. Mendel then carried out the selfing of F1 plants (i.e., selecting male and female plants from the same generation and using them as parents for developing next generation F2). Tall Tt Tt Tall tGametes T t T t Tall Tall Tall Dwarf 3 Tall 1 Dwarf On selfing of F1 plants, Mendel got 787 tall plants and 277 dwarf plants out of a total of 1064 plants in F2 generation. Thus, a ratio of 2.84 1 or 3:1 (in absolute figures between tall and dwarf plants) was obtained. In all cases, Mendel got a F2 monohybrid ratio 3:1.
Mendel's Law of Dominance (First Principle) .Each genetic character is governed by a pair of discrete units. These units are called factors. (Today, such factors are called alleles). Factors are found in pairs. Each pair governs a different character. Alleles of a pair influence the same character. .In a dissimilar pair of factors, one member of the pair dominates (dominant) the other (recessive), i.e when two factors of a pair are in heterozygous condition, then only one factor is able to express itself, while other one remains hidden. The factor, which is able to express itself, is called dominant factor while the other factor is called recessive factor. This phenomenon is called dominance. Mendel's Law of Segregation (Purity of Gametes) .It states that two factors (alleles) of a character remain in the form of a pair. During gamete formation, .When two factors (alleles) of a trait are in heterozygous condition then they do not contaminate/blend . At the time of gametogenesis (gamete formation), they segregate (get separated) and pass to their .In this way, a gamete receives only one factor (allele) for each character. This suggests that a they get separated /segregated from each other. each other. They remain in their pure form respective gametes in their pure form. homozygous parent produces all gametes that are similar. But a heterozygous individual produces two types of gametes, each having one allele / factor in equal proportion.
WATCH MY LIVE Course Watch my live course in Unacademy Plus section. Actual classroom feel at your home and live doubt removal .Go to www.unacademy.com/plus. Search for my live course and get yourself registered. ALL THE BEST