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Mr. Chapman Biology 20. Fungi Reproduce Sexually and Asexually. Fungi Have a Number of Reproductive Strategies. Depending on the favorability of conditions, fungi will reproduce either sexually or asexually.
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Mr. Chapman Biology 20 Fungi Reproduce Sexually and Asexually
Fungi Have a Number of Reproductive Strategies • Depending on the favorability of conditions, fungi will reproduce either sexually or asexually. • During favourable conditions, fungi reproduce asexually. During non-favourable conditions, fungi will lean towards sexual reproduction. • We will focus on two main groups (phyla) of fungi and their life cycles: Club Fungi and Bread Molds.
Something to Think About... Why do some fungi reproduce asexually during favourable conditions?
A Quick Note: Single-Celled Fungi • Single-celled fungi, including some yeasts, reproduce sexually and asexually. There are two forms of asexual reproduction for single-celled fungi: Fission and Budding
Yeah, we’ve all seen them... But have you eaten them? Bread Molds
Characteristics of Bread Molds • Form the molds you see on old, spoiled foods, such as the sandwiches I used to leave in my locker for months. • Members of the phylum get food by decomposing dead or decaying matter. • Asexual reproduction performed by spore production. Recall that spores are haploid (1n) gametes.
Asexual Bread Mold Reproduction • The sporangium bursts and releases spores (1n) to the surface that the mold is growing on. • The spore produces hyphae (1n) under the surface of the bread, which develops into a network of mycelia (1n). • Some hyphae (1n) grow above ground, and produce new sporangia that eventually release spores.
Sexual Reproduction of Bread Molds • Gametes (1n) of different mating types form at the tip of hyphae that are very close to each other under the surface. • The gametes fuse, forming a diploid zygospore (2n). This zygospore has a tough, thick outer layer, and can remain dormant for an extremely long time. • Later on, the zygote (2n) can produce a sporangium (1n) by meiosis, which grows into a new spore producing structure.
Characteristics of Club Fungi • Named for their club-shaped reproductive structures, called basidia, which are found on the undersides of mushrooms. • Some groups of these fungi cause diseases in plants. • Club fungi only reproduce sexually.
Sexual Reproduction in Club Fungi • Haploid nuclei (1n) within the basidia fuse to form diploid (2n) zygotes. • Zygotes (2n) then undergo meiosis to form haploid spores (1n), which are then released and dispersed by the wind. • Upon contact with the ground, the spores grow into hyphae of opposite mating types, fusing to form a diploid (2n) mycelium underground. • The mycelium grows a new fruiting body (the mushroom), and the cycle repeats itself.