Presentation on theme: "Ch. 21 Sec. 1 The Kingdom Fungi. I. What Are Fungi? A.Fungi - eukaryotic heterotrophs that have cell walls 1. Cell walls contain chitin, a complex carbohydrate."— Presentation transcript:
Ch. 21 Sec. 1 The Kingdom Fungi
I. What Are Fungi? A.Fungi - eukaryotic heterotrophs that have cell walls 1. Cell walls contain chitin, a complex carbohydrate
B. Depend on other organisms for food 1. Digest food outside of their bodies 2. Then food is absorbed 3.Some absorb nutrients from decaying matter in the soil C. Other fungi are parasites 1. Absorb nutrients from hosts
II. Structure and Function of Fungi A.Except for yeasts, fungi are multicellular B.Hyphae - thin filaments 1. Each hypha is only one cell thick
2. In some fungi, cross walls divide hyphae into cells with 1 or 2 nuclei 3. In the cross walls, there are openings through which the cytoplasm and nuclei can move Fig Pg. 527 Most fungi are made up of filaments called hyphae. In some fungi, the hyphae are divided by cross walls.
4. Some hyphae lack cross walls and contain many nuclei
C. Fungus Structure C. Fungus Structure 1.The bodies of multicellular fungi are composed of many hyphae tangled together into a thick mass called a mycelium 2.The mycelium permits a large surface area to come in contact with the food source through which it grows
3. A mushroom is the fruiting body of a fungus 4. A fruiting body – reproductive structure
Structure of a Typical Fungus Hyphae Fruiting body Mycelium Fig Pg. 528 The body of a mushroom is part of a mycelium formed from many tangled hyphae. The major portion of the mycelium grows below ground. The visible portion of the mycelium is the reproductive structure, or fruiting body, of the mushroom.
III. Reproduction in Fungi Most fungi reproduce both asexually and sexually
A.Asexual reproduction 1. Hyphae break off and begin to grow 2. Some produce spores a. Scatter and grow b. Produced in sporangia - located at tips of specialized hyphae called sporangiophores
B. Sexual reproduction 1. Two mating types a. “+” (plus) b. “–” (minus) 2. Meet and fuse a. “+” and “–” nuclei in one cell 3. Form a diploid zygote nucleus a. Enters meiosis b. Produces haploid spores – capable of growing into new organisms
IV. How Fungi Spread A. Dry spores - scatter easily in the wind 1. Need proper environment (temperature, moisture, and food) so they can grow B. Other fungi are specialized to lure animals 1. Disperse spores over long distances Puffball
21–1 The Kingdom Fungi Fungi are eukaryotic heterotrophs with cell walls made of chitin. Chitin is a complex carbohydrate. Fungi do not ingest their food. Instead, fungi digest food outside their bodies and then absorb it. All fungi except for yeasts are multicellular. Multicellular fungi are made up of thin filaments called hyphae (singular: hypha). Each hypha is only one cell thick. The bodies of multicellular fungi are made of hyphae tangled together into a thick mass called a mycelium. The mycelium allows a large surface area to come into contact with the food source through which the fungi grow. The fruiting body of a fungus is a reproductive structure growing from the mycelium in the soil beneath it. In a mushroom, the fruiting body is the aboveground part of the mushroom.
Most fungi reproduce both asexually and sexually. Asexual reproduction can occur when cells or hyphae break off and begin to grow on their own. Some fungi also make spores. In some fungi, spores are formed in structures called sporangia. Sporangia are found at the tips of hyphae called sporangiophores. Sexual reproduction in fungi usually involves two different mating types. One type is called “” (plus), and the other is called “” (minus). When the hyphae of a “” fungus meets the hyphae of a “” fungus, they fuse together in the same cell. After a period of growth and development, the nuclei form a diploid zygote. The diploid zygote enters meiosis, and produces haploid spores.
Spores of fungi exist in almost every environment. Many fungi produce dry, almost weightless spores that are easily scattered by wind. For these spores to grow, they must land in a favorable environment. Temperature, moisture, and food conditions must be in the right combination. Most spores, therefore, do not grow into mature organisms. In fact, the probability that a spore will germinate and grow into a mature fungus can be less than one in a billion.