The Prokaryotes & Virus Chapter 21

Bacteria: Quick Review Prokaryotic No nucleus Unicellular “Bacteria” Archaebacteria live in extreme environments Divide by binary fission Asexual reproduction

The Kingdom Fungi

Fungi: An Overview All fungi are: Eukaryotic Heterotrophic Multicellular Nonmotile

The Structure of Fungi Fungi are made up of one- cell thick, threadlike filaments called hyphae All of the hyphae put together, which makes up the body of the fungus, is known as a mycelium Fungal cells are surrounded by cell walls made of chitin

Fungal Motility & Nutrition Fungi are nonmotile However, the fungal mycelium can grow quickly in any direction if it is in a suitable environment Fungi do not ingest food, as animals do Instead, they secrete enzymes which break down molecules in the surrounding environment Because of their large mycelium, they have a lot of surface area to secrete enzymes and absorb nutrients

Fungal Reproduction Fungi are capable of sexual and asexual reproduction Instead of embryos (produced in animals), fungi produce spores Spores are reproductive structures that are incredibly mobile Spores are transported from one place to another by wind and other organisms

Asexual Reproduction Asexual reproduction is the default mode for fungal reproduction Spores are produced inside a fruiting body, which is projected above the mycelium

Asexual Reproduction The bodies and spores of fungi are haploid Dominant generation = haploid A haploid mycelium, therefore, produces haploid asexual spores by mitosis If an asexual spore is deposited in a favorable location, it will begin to develop a new mycelium by mitosis Asexual reproduction results in.

Sexual Reproduction The filaments of two mycelia of compatible mating types (similar to male/female) come into contact The two hyphae fuse together Haploid nuclei fuse together to form a diploid zygote Zygote then performs meiosis, producing haploid spores Spores are dispersed, starting the whole process over again These offspring are genetically.

Fungal Symbiosis Mycorrhizae Fungi and plant roots living together Fungus helps plant absorb minerals, organic materials, water Plant helps fungus eat by giving it photosynthetic sugars

Impact of Fungi on Humans Plants Fungi cause the majority of plant diseases, which impact the human food supply Basidiomycete plant pests Rusts and smuts Dutch elm disease, chestnut blight

Impact of Fungi on Humans Human Diseases Ascomycetes that attack the skin Athlete’s foot Ringworm Jock itch Yeast infections Penicillin, cyclosporin (organ transplants)

Impact of Fungi on Humans Food Mushrooms and truffles Cheeses, yogurt Yeasts Bread, wine, beer

Impact of Fungi on Humans Ecological Role “Earth’s undertakers” Decomposers Return carbon, nitrogen, phosphorus back to the soil to be used again

The “Kingdom” Protista

The Kingdom Protista Protists are: eukaryotic Mostly unicellular the “junk drawer” of taxonomy Protists are either: Plant-like = algae Animal-like = protozoa Fungus-like = water molds and slime molds

Algae Algae are plant-like protists Perform photosynthesis Perform 70% of all photosynthesis on Earth Individual algal cells are known as phytoplankton When grouped together, they are known as seaweeds

Algae There are 6 phyla of plantlike protists Dinoflagellates Diatoms Euglenoids Red algae Brown algae Green algae

Dinoflagellates Have 2 whiplike flagella Live primarily in oceans

Dinoflagellates “Red tide” Occurs when water is warm and there are plenty of nutrients Reproduce quickly under these ideal conditions The vast quantity of them turns the water red Many fish die Clogged gills Oxygen depletion

Diatoms Found in both fresh and salt water Produce protective shells of silica

Euglenoids Live primarily in fresh water Moves by whipping its flagellum Has light- sensing organelles

Red Algae Live in colonies  multicellular

Brown Algae Live in colonies  multicellular “Seaweed” in cool coastal water Eastern and western US

Green Algae Either unicellular or forming colonies Very closely related to plants Green algae are believed to be the evolutionary ancestors to modern plants

Protozoa Protozoa are animal- like protists Motile (able to move) Heterotrophic There are 4 major phyla of protozoa Zooflagellates Sarcodines Sporozoans Ciliates

Sarcodines Amoebae are the most familiar protozoa Sarcodines have flexible plasma membranes that they use for movement and engulfing food Pseudopodia “false feet” Amoeba often live in freshwater Contractile vacuole to pump out excess water

Sporozoans Plasmodium Causes malaria Carried by female mosquito Reproduces rapidly in human red blood cells and causes them to rupture, releasing the spores Drug-resistant populations are spreading

Ciliates Live in fresh or salt water Have many cilia for movement Fastest protists around – 1mm per second Paramecium is the most common genus Contractile vacuole maintains water balance

Water Molds and Slime Molds Fungus-like protists Have filaments and fruiting bodies similar to fungi Absorb nutrients from the soil, water, or tissues of other organisms Help to decompose dead organisms Three Major Groups Water Molds Acellular Slime Molds Cellular Slime Molds Live in wet places Incredible economic importance Irish potato famine