Biology · Glossary

What is Modes of division?

Also known as: generation time

Definition 1.19 University Biology — Year 2 · Chapter 1 — Diversity of Unicellular Organisms

A unicellular organism reproduces by dividing. Binary fission: the cell grows to twice its size and splits into two equal daughters (bacteria, Paramecium, Amoeba). Budding: a small daughter grows out of the mother and detaches (yeast; the mother keeps a scar and can bud some twenty times). Multiple fission: the cell grows large, then divides several times in quick succession inside the mother wall and releases 4, 8, 16 or more daughters at once (Chlamydomonas, the malaria parasite in a red cell). Under constant conditions the number of cells grows exponentially, N(t)=N02t/TN(t) = N_0\,2^{t/T} with TT the generation time: twenty minutes for E. coli in rich medium, a day for many algae, a week for some ciliates. (Growth as a function of food is treated in Chapter 2.)

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