Significance of Meiosis
The significance of meiosis for reproduction and inheritance was described in 1890 by German biologist August Weismann.
He pointed out that meiosis was necessary not only to maintain the number of chromosome sin the next generation but also to produce variation in next generation.
Maintain of the chromosomes number in next generation
ØMeiosis
is essential for sexual reproduction. In Human, diploid gamete-mother or germ
line cell undergo meiosis to produce haploid gametes.
ØMale
and female gametes unite to form diploid zygote, which undergoes repeated
mitosis and develops into a new diploid human.
ØPlants
life cycle shows alternation of generation.
The cell of sporophyte generation undergo meiosis to produce haploid
spores, which grow into haploid gametophyte generation. Gametophyte generation
produce haploid gametes through mitosis. The gametes combine to produce diploid
zygote. Zygote undergo repeated mitosis to become diploid sporophyte
generation.
Produce of variation
in next generation
ØThe chromosomes pairs of each parent undergo
crossing over during meiosis. So daughter cells . i.e. gametes have genetic
variation.
ØWhen
gametes fuse and form zygote, its genetic make is different from both parents.
ØThus
meiosis allows a species to bring variations in the next generation.
ØBeneficial
help organisms to adapt to the changes in environment.
Errors in Meiosis
ØDuring
anaphase I, chromosomes separate and go to opposite poles while during anaphase
II, sister chromosomre
separate. It is called disjunction.
ØSometime
the separation is not normal and it is called non-disjunction. This result in
the production of gametes which have either more or less than the normal number
of chromosomes.
Øif
such gametes fuses with normal gametes, it result abnormal chromosomes number
in next generation , for example 47 0r 45 chromosomes in human.
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