Sporulation (spore formation) is a type of asexual reproduction in which a parent organism produces large numbers of small, light reproductive cells called spores. Each spore can grow into a new individual.It is common in fungi such as the bread mould Rhizopus and the mould Penicillium. In Rhizopus, hyphae grow upwards and swell at their tips to form sporangia. Inside each sporangium, nuclei divide repeatedly by mitosis, and each nucleus becomes surrounded by a little cytoplasm and a tough wall, forming a spore. When the sporangium bursts, the spores are released and carried away by air currents.
Because the spores are made by mitosis, they are genetically identical to the parent, so the offspring form a clone.Features that make sporulation successful:
• enormous numbers of spores are made, so even if most land in unsuitable places, some survive;
• spores are tiny and light, so they are dispersed over long distances;
• many spores have thick protective walls and low metabolic rates, so they can stay dormant through dry or cold conditions and germinate when conditions become suitable.For example, a Rhizopus spore landing on moist bread at room temperature germinates and grows a new network of hyphae, called a mycelium, within a day or two.Note that mosses and ferns also produce spores, but theirs are made by meiosis and are genetically different from each other. In this lesson, sporulation means spores produced asexually by mitosis.
Because the spores are made by mitosis, they are genetically identical to the parent, so the offspring form a clone.Features that make sporulation successful:• enormous numbers of spores are made, so even if most land in unsuitable places, some survive;
• spores are tiny and light, so they are dispersed over long distances;
• many spores have thick protective walls and low metabolic rates, so they can stay dormant through dry or cold conditions and germinate when conditions become suitable.For example, a Rhizopus spore landing on moist bread at room temperature germinates and grows a new network of hyphae, called a mycelium, within a day or two.Note that mosses and ferns also produce spores, but theirs are made by meiosis and are genetically different from each other. In this lesson, sporulation means spores produced asexually by mitosis.