Principles of Inheritance and variation | Part 1 | TB 2024

Genetics is a branch of biology which deals with principles of inheritance
and its practices. Progeny resembling the parents in morphological and
physiological features has attracted the attention of many biologists.
Mendel was the first to study this phenomenon systematically.
While studying the pattern of inheritance in pea plants of contrasting
characters, Mendel proposed the principles of inheritance, which are
today referred to as ‘Mendel’s Laws of Inheritance’. He proposed that
the ‘factors’ (later named as genes) regulating the characters are found
in pairs known as alleles. He observed that the expression of the
characters in the offspring follow a definite pattern in different–first
generations (F1), second (F2) and so on. Some characters are dominant
over others. The dominant characters are expressed when factors are
in heterozygous condition (Law of Dominance). The recessive characters
are only expressed in homozygous conditions.
The characters never
blend in heterozygous condition. A recessive character that was not
expressed in heterozygous conditon may be expressed again when it
becomes homozygous. Hence, characters segregate while formation of
gametes (Law of Segregation).
Principles of Inheritance and variation | Part 1 | TB 2024
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