HEREDITY

Ø Heredity is transmission of characters, from one generation to the next generation, while variation refers to the differences shown by the individuals of the same species and also by the offspring of the same parents.

Ø All these can happen only due to chromosomes.

Constrasting characters of pea plant used by Mendel:

Dihybrid Cross Inheritance Two Genes and Law of Independent Assortment:

Ø Dihybrid cross involves the inheritance of two pairs of contrasting characteristics (or contrasting traits) at the same time.

Ø The two pairs of contrasting characteristics chosen by Mendel were shape and colour of seeds: round-yellow seeds and wrinkled-green seeds.

Types of Chromosomes based on the position of Centromere:

Ø Based on the position of centromere, the chromosomes are classified as

1. Telocentric

2. Acrocentric

3. Submetacentric

4. Metacentric

Structure of DNA:

Ø DNA is the hereditary material as it contains the genetic information.

Ø It is the most important constituent of a chromosome.

Ø The most widely accepted model of DNA is the double helical structure of James Watson and Francis Crick.

MIND MAP