1. BACTERIA ARE SINGLE- CELLED ORGANISMS WITHOUT A NUCLEUS Bacteria are the simplest form of life; there are more bacteria in your mouth than people on the planet. BACTERIA & ARCHAEA are the SMALLEST LIVING things. BACTERIA & ARCHAEA are found in MANY ENVIRONMENTS BACTERIA MAY HELP OR HARM OTHER ORGANISMS

2. BACTERIA & ARCHAEA are the smallest living things Bacteria are the simplest kind of life known (1cell with loops of genetic material-no nucleus; reproduces via binary fission) Bacteria have cell walls surrounding & protecting the soft cell membrane. Classify bacteria by external shape: SPIRAL-shaped occur in single strands ROD-shaped occur singly or in chains ROUND-shaped occur singly, in pairs, chains or clusters.

4. ARCHAEA & BACTERIA IN MANY ENVIRONMENTS ARCHAEA: single-celled organisms living in the most extreme environments (hot, cold, salty, etc.) METHANOGENS: archaea that make methane & die if exposed to oxygen (live in marshes & intestines of cows & termite) HALOPHILES: archaea that live in salty lakes & ponds THERMOPHILES: archaea that live in extreme heat or cold. (hot springs, under water volcanic vents, or buried deep in ice).

5. ARCHAEA & BACTERIA Some bacteria have chlorophyll & use sunlight for energy. (important food source in oceans & give off O 2 as well) Many bacteria are grouped by role they play in environment: PRODUCERS: transform energy from sunlight to usable forms. DECOMPOSERS: break down materials in dead or decaying organisms. (good recyclers!) PARASITES: organisms that live off a host and harm that host

7. Helpful v. Harmful Bacteria Decomposers break down material that other organisms can use to build up. Can break down & treat sewage to clean water or oil spills Can convert nitrogen gas into usable nitrogen compound for plants to use in building proteins to grow. Methanogen archaea also help cows & termites digest cellulose for food. Some diseases are caused by bacteria (tuberculosis, cholera, infant diarrhea) Cause symptoms by: Invade body, multiply & dissolve cells Poison with chemicals they made & released Poison with chemicals that are part of themselves VACCINES are used to help organisms get ready to fight bacteria they may be exposed to in the future.