Mr. Chapman Biology 20

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...

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?

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.

Reproduction in Bread Molds

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.

These ones, you’ve actually probably eaten...

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.

Reproduction in Club Fungi

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.