Genetics-And-Evolution-Principles-Of-Inheritance-And-Variation-1
Mendel’s Pea Plant Experiments:
Gregor Mendel conducted experiments with pea plants in the 19th century.
Chose pea plants due to distinct traits and easy cross-breeding.
Studied seven traits, each with two variants (e.g., flower color: purple and white).
Principles of Mendel’s Experiments:
Used controlled cross-fertilization.
Labeled generations as P (parental), F1 (first filial), and F2 (second filial).
Discovered Law of Segregation (allele separation) and Law of Independent Assortment (independent gene segregation).
Observed phenotypic ratios in F2 generations (e.g., 3:1 for monohybrid cross).
Phenotype:
Observable traits in organisms.
Mendel studied traits like flower color, seed color, and more.
Identified dominant (expressed) and recessive (masked) traits.
Monohybrid Cross:
Cross involving one specific trait.
Starts with purebred parental plants.
Produces F1 generation with all heterozygous individuals.
F2 generation exhibits 3:1 phenotypic ratio (e.g., 3 purple: 1 white).
Self-Pollination in F1 Plants:
F1 generation results from cross-breeding.
F1 plants are heterozygous for the trait.
Self-pollination of F1 plants results in F2 generation.
F2 generation exhibits phenotypic ratio based on dominant and recessive alleles.
Hybridization of Parents:
Hybridization involves breeding different individuals to create hybrids.
Examples in plants, animals (e.g., mule, liger), bacteria, and fish.
Used for desirable traits and improvements.
Phenotypic and Genotypic Ratio:
Phenotypic ratio is the proportion of observable traits.
Genotypic ratio is the proportion of genetic combinations.
Ratios depend on alleles and traits.
Monohybrid cross often results in 3:1 phenotypic ratio and 1:2:1 genotypic ratio.
