What is the importance of meiosis in creating variations?
2 Answers
The most significant important of meiosis in creating variations is that meiosis does not produce genetically identical gametes, which means that all offsprings produced are unique.
Explanation:
Meiosis differs from mitosis by the means of producing offspring. While mitosis involves only one parent (eg. binary fission - asexual), all offspring produces are genetically identical.
Meiosis, on the other hand, involves male gamete and female gamete. This does not only means that offspring's genetic codes will be varied, but also lead to the creation of unique human beings. This is due to the process of crossing-over at the chiasma on the chromosome. The most common saying is that DNA codes are different for all human beings accept identical twins. It is obvious that when the DNA information is different, no two individuals on Earth are exactly the same, even for identical twins.
You can also look at the cases of plants, where Punnett square is used to show the possible variations in plants, as done by Mendel.
Imagine if human beings practice mitosis, where all the younger generations have the same face.......
Recombination of genes inherited by an organism from the parents through male and female gamete is brought about during meiosis that occurs prior or during the gamete formation.
Explanation:
Meiosis is reduction division that occurs at the time of sporogenesis in plants and gametogenesis in animals.
The zygote (2n)is formed by the fusion of male and female gametes (n). The zygote has two sets of chromosomes, one set each contributed by the male and female gamete.
The genes are present on chromosomes . Two chromosomes of same type contributed by male and female parent are termed homologous chromosomes . The homologous chromosomes bear identical genes at corresponding loci. However, a particular gene may represent same allele or different allele . For example, gene for height in pea may represent allele for tallness on both the chromosomes or bear allele for tallness and dwarfness.
It may be emphasized that some genes present on two homologous chromosomes may be of same allele or alternate allele.
Recombination of genes present on chromosomes of homologous pair occurs during crossing over occurring during prophase I of meisosis.
Recombination of genes present on different chromosomes is brought about by random orientation of bivalents formed by two homologous chromosomes (during prophase I stage of meiosis) at metaphase I stage of meisosis and random orientation of chromosomes at metaphase II of meiosis.
The haploid gametes produced as a consequence of meiosis will not bear totally paternal or maternal genes but inheriting genes of both parents in different permutation and combination.
Subsequently random fusion of male and female gametes will result in further recombination.
Thus recombination of genes brought about during meiosis results in innumerable variations.
