Genetics : Mendel's Law of Inheritance
- 1. *Welcome to my channel Biology Simplify
- 2. Law of Dominance Law of Segregation Monohybrid Cross Law of Independent Assortment Dihybrid Cross
- 3. Law of Dominance Recessive alleles will always be masked by Dominant alleles TT tt (pure parents P generation) ½ T ½ T ½ t ½ t (gametes) cross T T t t Tt Tt Tt Tt F1 generation – Tt 100% Tall (hybrid) Genotype – 4 : 0 Phenotype – 4 : 0 Tall Short
- 4. Mendel’s 1st Law Law of Segregation Key concepts: At the time of gametes formation the two copies of each hereditary factor(Gene)Segregate so that offspring get one factor from each parent. Diploid organisms – chromosomes occur in Homologous pairs. Meiosis – homologous chromosomes separate , as a result pairs of alleles separate.
- 5. Monohybrid Cross (Single Trait) Law of Segregation TT Tt Tt tt T t T t TT tt Tall Short T (gametes) t t Tt F1 Tt Tt Self cross F2 Phenotype : - 3 Tall : 1 Short F2 Genotype : - 1 Pure Tall : 2 Hybrid Tall : 1 Short P F2 T 100% Tall A cross b/w pure breed pea plant, Homozygous Tall( TT) & Homozygous Short (tt) P Gen- one type gametes. F1- all Hybrid Tall offspring. F1 - two type gametes. F2- both Tall & Short offspring .(after Self cross of F1 offspring)
- 6. Mendel’s 2nd Law Law of Independent Assortment Independent Assortment : No mixing ,No association Key concept : This law states that genes for one trait are not inherited together with another trait. Dihybrid Cross : Segregation of seed color is independent of the seed shape, both parental and new combinations of characters appear in f2 offspring i.e. Assortment of gene of a pair is independent of the other pair.
- 7. Dihybrid Cross (Two Traits) Law of Independent Assortment P: YY RR yy rr Yellow, green, Round wrinkled YR yr (gametes) F1 YyRr self cross yellow, round YYRR YR Yr yR yr YR Yr yR yr YYRr YyRR YyRr YYRr YYrr YyRr Yyrr YyRR YyRr yyRR yyRr YyRr Yyrr yyRr yyrr F2 Phenotype – 9: 3: 3 : 1 F2 Genotype- 1: 2:1: 2: 4: 2: 1: 2: 1 F2
- 8. Incomplete Dominance & Co-dominance