Difference Between Mendel’s First and Second Law

Mendel’s First vs Second Law

Mendelian inheritance describes Mendel’s first and second laws in genetics. These laws mainly explain how a single trait is inherited from parents to offspring through the sexual reproduction in eukaryotic organisms. This phenomenon was first analyzed by Gregor Mendel in 1850s. During his experiments, he made control crosses between true-breeding garden pea varieties, which had easily identifiable inheritable differences including plant height, seed colour, flower colour and seed shape. He published his work results in 1865 and 1866. His findings were later on developed as Mendel’s laws. The difference between Mendel’s First and Second Law is explained below.

Difference Between Mendel's First and Second Law

Mendel’s First Law

Mendel’s first law is often called law of segregation, which describes the segregation of alleles and discrete inheritance of characteristics. The law further explains that during the production of gametes of an individual, chromosomes first separate and each gamete gets only one set of individual’s chromosome pair. This allele segregation process is known as meiosis.

Mendel’s Second Law

Mendel’s second law is also referred to as the law of independent assortment. It states that during meiosis alleles assort independently of one another, and they are passed to daughter nuclei with equal probability. The behaviour of independently assorting non-homologous chromosomes is considered in this law.

Difference Between Mendel's First and Second Law

What is the difference between Mendel’s First and Second Law?

• Mendel’s first law is called law of segregation while Mendel’s second law is called law of independent assortment.

• First law states that during meiosis, the two members of any allele pair possessed by an individual pass into different gametes. Second law states that the all the combination of alleles assort independently and are passed to offspring with equal probability.

• Mendel’s first law explains the behaviour of all chromosomes, whereas his second law explains the behaviour of non-homologous chromosomes.