While crossover occurs in prophase I, an independent assortment law can be observed during metaphase I and anaphase I of meiosis. In metaphase, for example, chromosomes randomly align along the metaphase plate. Mendel observed that true pea plants with opposite traits resulted in F1 generations, all expressing the dominant character, and F2 generations, which expressed dominant and recessive traits in a 3:1 ratio, and proposed the law of segregation. This law states that paired unitary factors – genes – must be evenly divided into gametes, so that offspring have an equal probability of inheriting one or the other factor. For the F2 generation of a monohybrid cross, the following three genotype combinations could result: homozygous dominant, heterozygous or homozygous recessive. Since heterozygotes can originate from two different signaling pathways receiving a dominant allele and a recessive allele from a parent – and because heterozygous and homozygous dominant individuals are phenotypically identical, Mendel`s law supports Mendel`s observed phenotypic ratio of 3:1. The same segregation of alleles is why we can apply the Punnett square to accurately predict the offspring of parents with known genotypes. The physical basis of Mendel`s law of segregation is the first division of meiosis, in which homologous chromosomes with their different versions of each gene are separated into daughter nuclei. The role of meiotic chromosome segregation in sexual reproduction has not been understood by the scientific community during Mendel`s lifetime. The image above illustrates the laws of Mendelian inheritance. Gamete separation and independent selection of characteristics occur in meiosis.

As a result, each offspring receives the full number of chromosomes, which contain randomly sorted alleles from each parent. Independent Assortment Law: The Independent Assortment Law is the second law of Mendelian inheritance. The law of independent assortment also stipulates that a cross between yellow, wrinkled (YYrr) and green, round (YYRR) parents would give the same offspring F1 and F2 as in the YYRR x yyrr cross. The segregation law is Mendel`s first law. It indicates that during meiosis, the alleles separate. The basic principles of this law are postulated as follows: Segregation law: The segregation law describes the behavior of non-homologous chromosomes. As with segregation, independent sorting occurs during meiosis, particularly in prophase I, when chromosomes line up in a random orientation along the metaphase plate. The exchange and recombination of genetic information between chromosomes also occurs in prophase I and contributes to the genetic diversity of offspring. The law of segregation is known as the law of purity of gametes because a gamete carries only one recessive or dominant allele, but not both alleles. The independent assortment principle describes how different genes separate independently from each other as reproductive cells develop.

Independent selection of genes and their corresponding traits was first observed in 1865 by Gregor Mendel during his studies of pea plant genetics. Mendel made dihybrid crosses, which are crosses between organisms that differ in terms of two characteristics. He found that trait combinations in the offspring of his crosses did not always match the trait combinations in parent organisms. Based on his data, he formulated the principle of independent assortment. Independent assortment principles describe that during gamete development, pairs of alleles are separated, which means that the characteristics are transmitted independently to the offspring. This law states that when two traits come together in a hybrid pair, the two traits do not mix and are independent of each other. Each gamete receives one of the two alleles during chromosome meiosis. When two sets of Mendelian entities are merged into a hybrid, one pair of features differs from the other pair of entities. Therefore, this means that the alleles are independent and do not affect the other alleles.

For example, a pea plant with round, yellow seeds was crossed with a plant with wrinkled green seeds. The law of segregation and the law of independent sorting are the first and second laws of Mendelian inheritance. The law of segregation describes how the alleles of a gene are separated into two gametes and joined together after fertilization. The law of independent sorting describes how alleles of different genes separate independently during gamete formation. This is the main difference between the law of separation and the law of independent assortment. The following presentation explains Gregor Mendel`s law of segregation and the law of independent assortment. These are two genetic rules that explain the separation of maternal and paternal genes during gametogenesis. Source: Shomus Biology hypothesis: The two pairs of traits are sorted independently according to Mendel`s laws.

When true breeding relatives are crossed, all F1 offspring are large and have swollen pods, suggesting that large and swollen strokes dominate over dwarf or narrowed strokes, respectively. Self-crossing of F1 heterozygotes leads to 2,000 F2 offspring. For the same tetrahybrid cross, what is the expected proportion of offspring that have the dominant phenotype at all four loci? We can answer this question with phenotypic proportions, but let`s do it the hard way – with genotypic proportions. The question concerns the proportion of offspring that are 1) homozygous dominant in A or heterozygous in A and 2) homozygous in B or heterozygous in B, etc. The quotation of the or and and in each case clearly indicates where the sum and product rules are to be applied. The probability of homozygous dominance in A is 1/4 and the probability of heterozygous in A is 1/2. The probability of homozygous or heterozygotes is 1/4 + 1/2 = 3/4 using the summation rule. The same probability can be obtained in the same way for each of the other genes, so the probability of a dominant phenotype for A and B and C and D according to the product rule is equal to 3/4 × 3/4 × 3/4 × 3/4 or 27/64.