Conjugation in Paramecium: Sexual Reproduction in paramecium Urdu / Hindi
Welcome to my YouTube channel power of knowledge academy. In this video you will learn about the process of Conjugation in Paramecium.
It is a kind of sexual reproduction unique to ciliates, in which a temporary union of two
individuals of the same species takes place for exchanging their genetic material.
The process takes place as follows:
Two individuals or preconjugants, lose their oral groove and cilia and come in contact and
firmly unite together.
Macronucleus disintegrates into the cytoplasm.
The micronucleus divides by meiotic division and then mitotic division to produce four haploid
daughter micronuclei.
Three daughter micronuclei degenerate and one survives, which then divides by mitosis
forming two unequal gametic nuclei – one the smaller migratory gametic nucleus and the larger
stationary gametic nucleus.
Migratory nucleus of one individual migrates through cytoplasmic bridges to the other
individual’s cytoplasm and fuses with the stationary nucleus forming a zygotic nucleus
or synkaryon. The two paramecia now termed exconjugants.
The exconjugants separate and the conjugation is over.
In each exconjugant zygote, nucleus divides mitotically three times producing 8
daughter nuclei.
Four daughter nuclei in each exconjugant enlarge to become macronuclei and
other 4 become micronuclei.
Three micronuclei disintegrate and disappear.
Remaining one micronucleus divides by binary fission, which produces 2
daughter Paramecia, each containing 2 macronuclei and 1 micronucleus.
Further division of each daughter cell forms 2 individuals, each containing one
macronucleus and one micronucleus.
Thus, each conjugant produces four daughter individuals at the end of
conjugation.
Significance of conjugation:
Conjugation rejuvenates individuals. If binary fission continues repeatedly for
several generations, Paramecium loses its vigour. To regain vitality conjugation is
resorted to and the process seems to rejuvenate and revive the lost vigour of
asexual reproduction. During conjugation the nuclear apparatus is reorganized.
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The periodic occurrence of conjugation ensures heritable variations in the
species.