Lecture 11 Bacteria and Protists Summer 2024 PDF

7/2/24 10:48 Lecture 11 Bacteria and Protists Eukaryotic Microorganisms...

7/2/24 10:48 Lecture 11 Bacteria and Protists Eukaryotic Microorganisms We will begin with Prominent members of ecosystems bacteria so bring outline from last time. Useful as model systems and in industry Protists represent much of the diversity Some are human and plant pathogens in the Eukarya – among the 20 most frequent microbial causes of death world-wide, 6 are eukaryotic Reading: Chapt. 5 Sects. 5.4 and 5.6 Chapt. 23 All Sects. Two groups: Protists and Fungi Common Features of Eukaryotic Cells Organelles of Eukaryotic Cells Sexual and Asexual reproduction Endoplasmic Reticulum (ER) Meiosis, Mitosis Protein synthesis – ribosomes Membrane-bound nucleus Plasma membranes (lipid bilayers) Golgi Apparatus Many have cell walls Chemical modification, packaging, secretion Membrane-enclosed organelles Mitochondria Powerhouses of cell - ATP by e transport and oxidative phosphorylation Site of TCA cycle Importance of Protists Protists - General Features Important link in food chains Domain – Eukarya – Plankton in aquatic habitats >60,000 different life forms – Radiolarians, mostly unicellular Diatoms and algae, slime molds, protozoa Foraminiferans I silica, calcium ↓ I Chlamydomonas Dictyostelium Giardia carbonate walls reef formation, ↓ ↓ ↓ diarrhea beach sand, limestone · watermelon snow lifecycle · Unicellular all for motile : 2 flagella oxygenic · stigma (eye) photosynthes's - For photaxis filled with photoreceptor (green) - · Strains have Chlorophyll 1 carotenoid (red) Gracial - melt  7/2/24 Protists - General Features Organelles Nuclei (1, 2 Terrestrial or aquatic or more) Some parasitic in humans, animals and plants Motile Ciliates are protists with 2 types of nuclei – cilia, flagella or pseudopodiaD Micronucleus Reproduction: - "true nucleus”, mitosis – Sexual and/or Asexual Macronucleus - Thousands of short, linear chromosomes + genes for growth and feeding stop here 0 : 00 718124 Protist Vacuoles and Organelles Metabolism and Nutrition Pseudopodia Movement and Feeding Nucleus Endoplasm Metabolism – can be photosynthetic (oxygenic) – also chemoorganoheterotrophs and mixotrophs (organic and inorganic) Nutrition – solid nutrients by phagocytosis – soluble nutrients by facilitated diffusion and Plasmalemma Phagocytic Vacuole Contractile Vacuole active transport Osmoregulatory (Plasma Membrane) Food digestion Fills with and expels water in a cyst Many Protists are Capable of Encystment and Excystment rang Encystment: – development into dormant stage - cyst Representative Protists – protection, transmission Excystment: – escape from cyst to metabolically active, motile form - trophozoite 2  7/2/24 04:34 Chlamydomonas Life Cycle of Unicellular green algae Dictyostelium ① Cell wall of cellulose A Cellular Free-living amoeboid cells Slime Mold Spores Oxygenic photosynthesis ② ↓ Sigmal= cAMP germinate Aggregate to form- Motile via 2 flagella motile slug Stigma (eyespot) I~ - For phototaxis Fruiting body - Filled with photoreceptors Nutrition = bacteria with spores Y① formatizes Watermelon (pink) snow by phagocytosis ↓ Strains have Chlorophyll and mature spore release carotenoid pigment (red) ↓ Contribute to glacial melt spore germinate into amoeboid cells Developmental Forms of Dictyostelium Giardia Protozoan parasite > spores - Human pathogen, Giardiasis – Cysts ingested stugg – Trophozoites attach to intestine – Disrupts nutrient and water flow – Severe diarrhea, fluid loss – Backpackers, if filtering ↓ water, ensure filter 15 glug removes cyst form Naegleria fowleri - The Alveolata is a - Trophozoite (infectious) large group of protists that includes the Free-living, aquatic, amoeba Dinoflagellates: Corganism) Thermophile- warm, high nutrient, - 2 flagella in grooves - fresh water longitudinal and transverse Trophozoite enters nose, - Toxic "red tides" travels to brain and destroys tissue causing brain Ciliates swelling and death - Cilia for movement singled-cell animals - 2 types of nuclei Primary amebic Source: www.cdc.gov meningoencephalitis (PAM) - 3  7/2/24 38:43 The Alveolata also Cryptosporidiosis Oocysts includes the Apical Complex Oocysts of Cryptosporidium apicomplexans calcium and enzyme transmitted in contaminated water that are important penetrate release to Common cause of waterborne causes of human host cells disease disease Milwaukee 1993, largest known outbreak in U.S. over 400,000 cases Cryptosporidiosis Oocyst features: tophozrite–Cryptosporidium Small (not easily filtered) Chlorine resistant Tachyzoite Toxoplasmosis protozoan Stable for months –Toxoplasma Only 8-10 to cause infection After ingestion, oocysts undergo excystment Sporozoite Malaria –Plasmodium become trophozoites in intestines Toxoplasmosis Toxoplasma infected mice lose their fear of cats, which is Oocysts of Toxoplasma in raw or undercooked meat, good for both cats and the also in cat feces parasite, the cat gets an easy pool or lake meal and the parasite gets Mice a natural reservoir - into the cat’s intestinal tract, the only place it can sexually Cats also hosts, required to complete sexual cycle reproduce and continue its cycle of infection. Ingested oocysts become tachyzoites – localize in neural and muscle tissue can enter brain Infection triggers permanent Can this parasite can cross placenta long-term behavior change in exert desired mice - mechanism largely change in Avoid changing cat litter during pregnancy unknown. complicated rodent behavior? 49:23 Malaria Distribution of Malaria Caused by 4 species of Plasmodium Plasmodium falciparum – apical complex Transmitted by bite of infected female Anopheles mosquito Sporozoite 300 million cases/year worldwide 4  7/2/24 53 : 00 Malaria growth 60:35 In liver, Sporozoites become Merozoites Malaria - Clinical Merozoites infect red blood cells (cyclic) Parasite forms knobs Periodic chills, fever Q on RBC surface Anemia – disrupted blood flow Why? Liver - hypertrophy Due to the accumulation of infected RBC that impair circulation and oxygen delivery tissues Copyright © The McGraw-Hill 25 Companies, Inc. Permission required for reproduction or display. Malaria - Control, Prevention, Treatment Mosquito control - wetland drainage, insecticides, netting Genetically modified mosquitoes? Drugs Chloroquine Parasite degrades hemoglobin as nutrient Release toxic heme Parasite polymerize heme into non-toxic form Drug blocks polymerization Malarone - block e- transport and pyridine synthesis 5