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PinkMonkey Online Study Guide-Biology

CHAPTER 7 : CLASSICAL OR MENDELLIAN GENETICS

Definition : "Genetics is the study and understanding of the phenomena of heredity and variation."

The term ’genetics’ was first coined by Bateson in 1906. In Latin, it means genesis or origination of organisms.

Heredity is the transmission of characters from one generation to the next, i.e., from parents to their offspring. Because of heredity, the offspring resemble their parents. Heredity is the essence of self-reproduction. It is owing to heredity or self-reproduction that we commonly observe the phenomenon of "like begets like", i.e., a seed of mango develops into a mango tree, or the offspring of a dog is a puppy, and that of human beings is a human being only.


Variations are the visible differences between the parents and the offspring, or between two offsprings of the same parents.

An offspring receives all the characters from its parents and yet, an offspring is never an exact copy of its parents. Similarly, no two offsprings of the same parents are identical (exception : identical twins).

In order to understand the principles of inheritance and to discover the reasons for the variations, Mendel began a systematic search during the second half of the nineteenth century. For this, Mendel experimented on garden pea plants and performed various crosses with great precision, care and objectivity. He carefully counted the plants resulting from such crosses and kept statistical records of successive generations with the accuracy of a mathematician.

Table of Contents

7.0 Introduction
7.1 Gregor Mendel
7.2 Mendel's Experiment on Sweet Pea
7.3 Terminology Used
7.4 Law of Dominance
7.5 Monohybrid Ratio
7.6 Law of Segregation
7.7 Dihybrid Ratio
7.8 Law of Independent Assortment
7.9 Test Cross or Back Cross
7.10 The Concept of "Factor"

Chapter 8





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