Viruses, Bacteria, Archaea, Protists, Fungi Classification Viruses, Bacteria, Archaea, Protists, Fungi

Bacteria

Eubacteria Structure Unicellular, prokaryotic organisms Large circular chromosome Cell walls (peptidoglycan) Cell wall prevents osmotic (water) rupture.

Prokaryotes are the foundation of life on earth Decompose dead organisms Decomposers, saprobes, saprophytes Put good nitrogen into air Live in our digestive system and are also used in the food industry Cheese, yogurt, etc Used to decompose waste in sewage Disesase causing bacteria – Usually produce toxins. Ex- bacteria that causes botulism (paralyzes nerve cells)

Some Prokaryotes Cause Disease Bacterial Examples: cholera, diphtheria, leprosy, Lyme disease, meningitis, the plague, pneumonia, syphilis, gonorrhea; tetanus, tuberculosis, strep throat. See book for more. Antibiotics are the most effective means of fighting bacterial infections Penicillin breaks down cell wall and allows rupture **No known Archaea cause disease

Archaea

Major Groups of Archaea Extremophiles-3 types Methanogens: are poisoned by oxygen use CO2 as the electron acceptor in respiration produce methane as a waste product Halophiles- lives in very saline places Thermophiles (aka hyperthermophiles)

Archaeabacteria vs eubacteria Used to be grouped with bacteria and called Monerans Now believed eukaryotes “split” from archaeal line of descent Differences between Arch and Bac: Archaea have “unusual” diverse lipids in membrane that allow them to live under extreme conditions Cell walls composed of polysacc and some only are entirely protein. **A few recently discovered have no wall (not on test, just FYI) Similarities between Arch and Euk: Arch and Euk share some of the same rRNA sequences and ribosomal proteins Similar tRNA Some Archaea have introns; bacteria do not

The Origin of the Eukaryotic Cell Eukaryotic cells arose through a combination of 2 processes: Membrane Infolding: Produced all the membrane-bound organelles except the mitochondrion and the chloroplasts. Endosymbiosis: Mitochondria and chloroplasts once prokaryotic cells that were ingested or absorbed by other cells.

Protista

Kingdom Protista Very diverse group of organisms Most are unicellular Currently being phylogenetically reclassified based on common DNA sequences, proteins, and therefore common ancestors Most are unicellular The most elaborate cells of all the kingdoms

Kingdom Protista Most are aerobic & use mitochondria for respiration Some are autotrophs, some are heterotrophs 3 types: ingestive, absorptive, photosynthetic.

Amoeba- moves and ingests using pseudopodia

Ciliates Paramecium- has both a macro and micro nucleus, so it has a “reserve” copy of genome. Macro regulates metabolism and micro is used in conjugation.

Flagellates Euglena- unique flagellate. Both autotrophic and heterotrophic

Diatoms Contain silica “shells”- forms diatomaceous earth

Volvox- single cells, but colonial

Red Tide

More Plant-Like Protists P. Phaeophyta – the brown algae include the largest seaweeds, the kelps (**multicellular) P. Rhodophyta – the red algae include the red seaweeds, some encrusted and common in coral reefs

Fungi

What is a fungus? Most are multicellular Cell walls made of chitin. Heterotrophic Nonphotosynthetic Digest food outside bodies (using enzymes) and absorb it Some live off of dead organic matter Decomposers

Structure and Function of Multicellular Fungi Composed of tiny filaments called hyphae Hyphae are long strings of cells. Mass called mycelium. Some species can grow a km of hyphae/day! Can reproduce asexually by releasing haploid spores Unicellular fungi-yeast Multicellular ex: mushrooms, molds

Ecological Impacts of Fungi Decomposers! Important nutrient recyclers Some are pathogens, such as ringworm and athletes foot.Plant pathogens--Dutch elm disease, Chestnut blight • Some produce deadly toxins-ex-some species of mushrooms • We use them for their antibiotics-penicillium. Produce enzymes that rupture bacterial cell walls