Principles of genetic inheritance are followed when traits or characteristics are passed from one to the next generation. This principle was first observed while analyzing the meiosis process by Gregor Mendel, who later went on to propose the three laws of inheritance.
When a cell replicates its DNA and divides in two stages to produce four gametes, meiosis takes place. Meiosis produces only one copy of each chromosome as they are haploid, unlike the mitotic division. The diploid cell called the zygote, formed as a result of the fusion of the egg and the sperm goes onto mature into an individual organism. The zygote consists of one set of the chromosome from each parent, which determines the phenotype of the newly formed individual. Alternative copies of genes are known as alleles. Humans possess two alleles for each gene.
The Law Of Segregation
It proposes the following – During meiosis, two alleles are separated from each other. Precisely, during the second stage of meiosis, two copies of each chromosome are isolated from each other which causes segregation or separation of the two distinct alleles from one another that are present on those chromosomes.
For a particular gene, a parent may possess two distinct alleles, each located at one copy of a given chromosome. Segregation takes place so that each sex cell carries only one allele for each gene.
The Law Of Dominance
It states the following – If one parent has two copies of allele X – the dominant allele, and the other parent has two copies of allele x – the recessive allele, in that case, the child inherits Xx genotype exhibiting the dominant phenotype.
We call a trait to be dominant when it is always expressed and appears in the offspring. Dominance illustrates the equation between the two alleles. An allele is said to be dominant if the offspring inherits two distinct alleles from each of the two parents and only one allele is evident in the offspring through its phenotype.
The Law Of Independent Assortment
The third law stated by Mendel is as follows – The segregation of the allele pair into two daughter cells during the second stage of meiosis division does not affect the way in which the other allele pair gets separated or segregated.
Through one gene, when a characteristic is inherited, it is independent of the characteristics or traits which are inherited through other genes since genes are present on different chromosomes which are separately classified during meiosis into daughter cells.
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