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Bacteria pp. 108 to 112 EUKARYOTES (TRUE NUCLEUS) (PLANT AND ANIMAL CELLS) PROKARYOTES (PRE-NUCLEUS) (BACTERIA) Nucleus No nucleus Lots of chromosomes Usually one chromosome + some plasmids Mitochondria No mitochondria Chloroplasts in plant cells No chloroplasts Larger Smaller Mitotic cell division Simple binary fission (split into two) Flagellum in animal cells (some) Simple flagellum Bacteria: General Info • Two kingdoms: Archaebacteria (early bacteria) and Eubacteria • Unicellular (organism is singlecelled); can be grouped into colonies • Do well in damp environments, will become inactive in dry environments • No nucleus but has single chromosome and small plasmids, which is also genetic information Archaebacteria – 3 groups Most live without O2 in extreme environments • Thermophiles – live in envs hotter than 45°C (eg. Hot springs) • Methanogens – No O2, but abundant CO2/H2; produce methane gas – Swamps, marshes, volcanoes, intestines of mammals • Halophiles – Live in salty environments (eg. Salt lakes, salt flats) Thermophiles in hot springs of Yellowstone Nat. Park Methanogens in cow intestines is a source of fossil fuel emission. However, methane gas can be used as a source of electricity since it is a natural gas! Halophiles love salt. Middle picture is the Dead Sea! Eubacteria & Structure • Most bacteria fall into this kingdom • Flagella – act as a propeller to move cell • Capsule – sticky coat, protective layer (protects from host’s immune system), seen in disease-causing bacteria • Pili – help bacteria attach to each other and surface, also helps with movement • Genetic material – floats in cytoplasm, no nucleus, 1 chromosome and several plasmids • Ribosomes, cell membrane, cell wall, cytoplasm – see Unit 1 Classifying Bacteria 1. 2. 3. 4. By Shape By Gram Staining By whether they need O2 to live or not By the type of food they need Classification: Shape • Most bacteria are found in groups rather than individual cells. Large groups are called colonies. • Spherical (cocci, sin: coccus) • Rod-shaped (bacilli, sin: bacillus) • Spiral (spirilla, sing: spirillus) Classification: Gram Staining • Bacteria have a polymer called peptidoglycan in cell wall. • Bacterial cell walls may react with a chemical stain called Gram stain. If they do react, then they are called “Gram-positive bacteria” (more polymers = thick wall) and will be purple. • If they don’t react, then they are called “Gramnegative bacteria” (less polymers = thin wall) and will be pink. Classification: Oxygen • Aerobic bacteria need oxygen to live – Eg. Tuberculosis bacteria • Anaerobic bacteria do not need oxygen to live – Eg. Gangrene, botulism, tetanus bacteria • Most bacteria can live with or without oxygen, such as E. coli. Classification: Food • Autotrophs – make own food using sunlight (like plants) • Chemosynthetic – make own food from chemicals in their env. like methane) • Heterotrophs – get food from consuming other organisms, either living or dead most common type Reproduction • Reproduce asexually by binary fission – Parent cell begins to divide – Cell doubles its cytoplasm & cell wall making enough for 2 cells. It replicates its DNA (exact copy) – When cell has doubled all of its components, a cross-wall is formed. Parent cell begins to pinch into two. – Two daughter cells are formed. They are exact copies of each other and the parent cell. Reproduction • Some bacteria can reproduce sexually by conjugation – Two different bacteria cells (one donor and one recipient) make contact – A sex pilus (tube) is formed – One strand of a plasmid moves through pilus to the other cell. – Recipient cell makes complimentary strand of plasmid, as well as donor cell. – Bacteria separate