Reproduction
Ciliates can undergo both asexual and sexual reproduction. Asexual reproduction occurs by binary fission. The micronucleus undergoes mitosis and the macronucleus elongates and splits in half. The cell then divides in two. Both new cells each obtain a copy of the micronucleus and macronucleus. By contrast, sexual reproduction involves the exchange of genetic material (or conjugation) between two organisms of different mating type (akin to sex, but more than two mating types can exist). This often occurs when food is rare. The two cells form a bridge between their cytoplasms, the micronuclei undergo meiosis, the macronuclei disappear, and the haploid micronuclei are exchanged over the bridge. The cells separate and form new macronuclei from their micronuclei. The two cells then divide, forming four new cells.
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Famous quotes containing the word reproduction:
“The chief function of the city is to convert power into form, energy into culture, dead matter into the living symbols of art, biological reproduction into social creativity.”
—Lewis Mumford (1895–1990)
“The atmosphere parents wish to create when talking with children about birth and reproduction is warm, honest, and reassuring, one that tells children they are free to ask questions as often as they need to, and you will answer them as lovingly as you know how.”
—Joanna Cole (20th century)
“Were I called on to define, very briefly, the term Art, I should call it “the reproduction of what the Senses perceive in Nature through the veil of the soul.” The mere imitation, however accurate, of what is in Nature, entitles no man to the sacred name of “Artist.””
—Edgar Allan Poe (1809–1845)