Principles of Inheritance and Variation:

1. Mendel’s Experiments:

Gregor Mendel conducted experiments with pea plants, studying traits like flower color, seed shape, and pod color.

2. Mendel’s Laws:

Law of Dominance:

Dominant alleles mask the expression of recessive alleles.

Dominant alleles are represented by uppercase letters (e.g., A), and recessive alleles by lowercase letters (e.g., a).

Law of Segregation:

Alleles segregate during gamete formation.

Gametes carry only one allele for a trait.

Law of Independent Assortment:

Alleles of different genes segregate independently during gamete formation.

Assortment of alleles for one trait doesn’t influence another trait.

3. Genotype and Phenotype:

Genotype: Genetic makeup (e.g., AA, Aa, aa).

Phenotype: Observable trait (e.g., purple flowers, white flowers).

4. Punnett Squares:

Used to predict offspring genotypes and phenotypes in genetic crosses.

5. Monohybrid and Dihybrid Crosses:

Monohybrid: Study of one trait inheritance.

Dihybrid: Study of two different trait inheritances simultaneously.

6. Variations:

Differences in traits among individuals.

Result from different allele combinations inherited from parents.

7. Role in Evolution:

Variations and natural selection drive the evolution of species.

Law of Dominance:

Dominant alleles mask the expression of recessive alleles.

Dominant alleles are represented by uppercase letters (e.g., A), recessive alleles by lowercase letters (e.g., a).

Homozygous dominant (AA), heterozygous (Aa), and homozygous recessive (aa) genotypes.

Law of Segregation:

Alleles segregate during gamete formation.

Each gamete carries one allele for a trait.

Explains inheritance of single traits.

Law of Independent Assortment:

Alleles of different genes segregate independently.

Assortment of alleles for one trait doesn’t affect another.

Explains inheritance of multiple traits simultaneously.