state the law of independent assortment explain this law with the help of dihybrid cross between round and yellow coloured seeded pea plants and wrinkled and green coloured seeded pea plants 5marks
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Answer:
Explanation:
According to the law of independent assortment, when two pairs of traits are combined in a hybrid, one pair of traits segregates independent of the other pair of traits. Which means that the allele a gamete receives for one gene does not influence the allele received by the same gamete for another gene. For example, a pea plant with round and yellow seeds was cross-pollinated with a plant that had wrinkled and green seeds.
The F1 hybrids had all round and yellow seeds. Upon self pollinating the F1 hybrids, in the F2 generation, new combinations of traits appeared in the following ratios: 9/16 were yellow round, 3/16 were yellow wrinkled, 3/16 were green round and 1/16 were green wrinkled. I.e., 9:3:3:1 ratio. The new combinations were possible only because the alleles of genes coding for seed colour and seed shape were independently assorted in the gamete
Answer:
The Law of Independent Assortment states that different genes and their alleles are inherited independently within sexually reproducing organisms. During meiosis, chromosomes are separated into multiple gametes. Genes linked on a chromosome can rearrange themselves through the process of crossing-over. Therefore, each gene is inherited independently. This law describes the random inheritance of genes from maternal and paternal sources. According to the Law of Segregation, each chromosome is separated from its homolog, or counterpart, during meiosis. As such, the maternal and paternal chromosomes from your parents are “independently assorted”, meaning that chromosomes from the same source do not have to end up in the same gamete.
For instance, one gamete can end up with all maternal chromosomes, while another can have a mixture of both maternal and paternal chromosomes. This also means that the genes on these chromosomes are independently assorted. In effect, the Law of Independent Assortment creates a large amount of variety based on different combinations of genes which have not previously occurred.
In one instance, genes cannot be assorted completely randomly. This occurs with linked genes, or genes which share the same chromosome. However, the process of crossing-over during meiosis ensures that even these genes get rearranged. During crossing-over, homologous parts of maternal and paternal chromosomes can be exchanged. This ensures that even linked genes get independently assorted.
Independent assortment occurs during the process of meiosis. Meiosis is similar to mitosis, only the final product is gamete cells. Gamete cells have half the DNA of regular, diploid cells and are considered haploid. This is a necessary part of sexual reproduction which allows two gamete cells to then fuse together to create a diploid zygote, containing all the DNA necessary to create a new organism.
To understand when independent assortment occurs, you must also understand the Law of Segregation. This law states that during meiosis, the two different copies of every gene are sorted into different gamete cells. The law of independent assortment, on the other hand, deals with the maternal and paternal sources of DNA being separated at random. To see these concepts in action, look at the image below:
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