Law of Segregation And Law of Dominance

Last Updated : 06 Dec, 2023

Law of Segregation and Law of Dominance are the fundamental principles in genetics, formulated by George Johann Mendel, known as "father of genetics". These are laws that explain the inheritance of traits from the parent cells. Law of Segregation demonstrates that every living organism has one pair of alleles and these alleles get separated during gamete formation thus each gamete has one allele. This results in the passing of one allele from both parents to their offspring.

The Law of Dominance stipulates that a heterozygous individual has two alleles for a single particular trait, but the dominant allele will suppress the other allele thus deciding the phenotype of an individual. For instance, father's skin color is black and mother's skin color is bright, but dominant allele in this is black, so the phenotype of the individual will be black.

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What is Inheritance?

Inheritance is defined as the transmission of traits or characters from parents to their offspring. He studied the pattern of inheritance of contrasting characters in pea plants and proposed the principle of inheritance, known as the 'Mendel law of inheritance'. The law includes the Law of dominance, the law of segregation, and law of independent assortment.

Mendel stated that the characters that are regulated by factors (genes) are found in pairs, known as alleles. The expression of the character in the offspring follows a definite pattern in the first generation (F1), second generation (F2), and so on. Based on the experiment on the monohybrid cross, he formulated the first two laws of inheritance: the law of dominance and the law of segregation.

Law of Dominance

The law of dominance states that when factors are in heterozygous conditions, dominant characters are expressed unless recessive characters are in homozygous conditions.

The law of dominance is Mendel's first law of inheritance. It has the following features:

Characters are regulated by distinct units called 'factors'( later known as genes).
These factors are present in pairs.
In heterozygous pairs, one factor of the pair will dominate the other.

The law of dominance explains that in a monohybrid cross, there is an expression of only one of the parental characters or trait cross in F1 and an expression of both the characters in the F2 generation.

Mendel cross-pollinated two plants that differed in one specific character, that is, the height of the pea plant, one with a tall height and the other with a short height. The height of all the offspring was tall. He called this generation as F1 generation. Next, he crossed two of the F1 plants with each other and observed that the resulting offspring, the F2 generation, had a 3:1 ratio of tall to short plants. This means that the trait for tall height was dominant over the trait for short height.

The trait which expresses itself in the F1 generation is called the dominant trait, and which is suppressed is called the recessive trait. Therefore,

Also Read: Difference between Dominant and Recessive Trait