1 / 21

Chapter 31 FUNGI (Part 1)

Chapter 31 FUNGI (Part 1). Introduction, Ecological Impacts and Phylogenetic Relationships Wesley Jensen, Andrew Kam, Frank Zhang, Jeff Zhang. Introduction. Fungi are mostly eukaryotic, and multicellular.

viveka
Download Presentation

Chapter 31 FUNGI (Part 1)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 31FUNGI (Part 1) Introduction, Ecological Impacts and Phylogenetic Relationships Wesley Jensen, Andrew Kam, Frank Zhang, Jeff Zhang

  2. Introduction • Fungi are mostly eukaryotic, and multicellular. • Fungi are unique organisms that differ from other eukaryotes in nutritional mode, structural organization, growth, and reproduction. • Fungi and Animals rose from the same ancestor.

  3. Absorptive Nutrition • Fungi acquire their nutrients by absorptive nutrition. • Small organic molecules are absorbed from surrounding medium. • Fungi digest food outside its body by secreting powerful hydrolytic enzymes into the food.

  4. Absorptive Nutrition cont. • The absorptive mode of nutrition specializes fungi into three types: • Saprobic (decomposers): absorb nutrients from nonliving organisms. • Parasitic: Absorb nutrients from cells of living hosts. Some are pathogenic. • Mutualistic: Absorb nutrients from host, yet reciprocate with functions that aid partners. (aid with uptake of minerals from soil)

  5. Fungi Growth • Bodies of fungi are constructed of units called hyphae. • Hyphae: minute threads composed of tubular walls surrounding plasma membranes and cytoplasm. • Hyphae form a network called mycelium, which is the “feeding” network of the fungus.

  6. Fungi Growth cont. • Most fungi are multi-cellular with hyphae divided into cells by cross-walls (septa). • The septa have pores large enough to allow ribosomes, mitochondria, and nuclei to flow from cell to cell. • The hyphae are built from chitin (polypeptide similar to chitin found in external skeletons of insects)

  7. Fungi Growth cont. • Some fungi are aseptate, meaning their hyphae are not divided into walls. • They are known as coenocytic fungi. • Instead, they consist of a continuous cytoplasmic mass with hundreds or thousands of nuclei. • Fungi usually have modified hyphae called haustoria which penetrate tissues of a host cell.

  8. Fungal Reproduction (Asexual) • They reproduce by releasing spores which are produced from specialized hyphal structures. • Spores are created asexually, and are carried by wind or water. • They germinate if they are in a moist area.

  9. Fungal Reproduction (Sexual) • Sex is a contingency mode of reproduction that occurs when there has been a change in the environment. • Sexual reproduction results in greater genetic diversity among offspring.

  10. Fungal Sex Cycle • Syngamy is the sexual union of cells that form two individuals. • There are two stages: • Plasmogamy: Fusion of Cytoplasm • Karyogamy: Fusion of nuclei.

  11. Plasmogamy • In plasmogamy, the nuclei from each parent cell pair up but do not fuse, this forms a dikaryon (two nuclei) • Instead they coexist, providing advantages in the cell’s life. • One haploid genome compensates for harmful mutations in the other nucleus.

  12. Karyogamy • In karyogamy, the nuclei fuse, forming a diploid cell that undergoes immediate meiosis.

  13. Ecosystems Depend on Fungi as Decomposers and Symbionts • Breakdown of wood, which makes nutrients available to living organism, became a dominant group of organisms about 250 million years ago • Without fungi and bacteria, plants and animals would starve because elements taken from soil wouldn’t be returned

  14. Continued • Fungi’s invasive hyphae enter the tissues and cells of dead organic matter and hydrolyze polymers. • Fungi can decompose anything from fruits/dung/forest litter to shower curtains and wooden boats. • We lose 10% to 50% of the world’s fruit harvest due to fungal attack. • Ethylene, a plant hormone that causes fruit to ripen also stimulates fungal spores on the fruit surface to germinate, causing the invasion of the fungi.

  15. Some Fungi are Pathogens • Plant diseases caused by fungi: • Ascomycete that causes Dutch elm disease has drastically changed the landscape of NE United States • Aspergillus which is a species of mold which could contaminate improperly stored grain secretes aflatoxins which is a carcinogenic • Ergots, caused by one type of ascomycete, that are ground with rye could cause humans to have hallucinations, temporary insanity, nervous spasms, gangrene

  16. Phylogenetic Relationships of Fungi • Fungal ancestors were aquatic flagellated organisms. • Flagellated cells were lost as they became adapted for life on land. • The differences between the Zygomycota, Ascomycota, and Basidiomycota are focused on their solutions to reproducing and dispersing on land. • Comparisons of RNA show that fungi are more closely related to animals than to plants.

  17. Many Animals, including humans, eat fungi • A variety of mushrooms are consumed in various cultures. • Only an expert can determine safe to consume mushrooms. • There is no simple rule to determine poisonous and nonpoisonous. • Truffles are the most commonly consumed mushroom.

More Related