BACTERIA

• Basic structure:– Prokaryotes (no nucleus or membrane-bound

organelles)– Single-celled– Single circular piece of DNA– May have pili (attachment) or flagella

(movement)

BACTERIA

Know the basic structure of a prokaryotic cell

BACTERIABasic cell shapes:

• Bacillus: Rod- shaped cells:

• Coccus: Round-shaped cells:

• Spirillum: Spiral cells:

Be able to draw or recognize bacterial shapes by their names.

Draw these shapes in your notes.

BACTERIANamed by arrangement

• Strepto: bacteria that form filaments are identified by this prefix. Example: streptococcus and streptobacillus

• Staphylo: species that form clusters are indicated by this prefix. Example: staphylococcus.

BACTERIASTRUCTURE

• Capsules: outside of cell wall, gel-like layer• Types of cell walls:

– Gram positive: treatable with antibiotics– Gram negative: difficult to treat with antibiotics

• Endospores: some form thick walls around their chromosomes when exposed to harsh conditions.– May germinate years after they were formed

• Pili: adhere to surfaces and aid in conjugation– Exchange of genetic material with another bacterium

BACTERIAObtaining energy

• Photosynthetic: – Cyanobacteria which are thought to have made

the Earth’s oxygen atmosphere

• Chemoautotrophic: obtain energy from inorganic molecules such as ammonia, or organic such as methane.– Many live in soil and help to fix nitrogen to a

form commonly used by plants

BACTERIAObtaining energy, cont.

• Heterotrophic: Most bacteria– these bacteria are the principle decomposers

on Earth.– Can be aerobic or anaerobic– Both helpful and harmful

BACTERIAPathogenic

• How do they harm us? By1. Metabolizing the host- breaking down organic

material of the host (i.e.. your tissue) and absorbing them.

2. Metabolizing secretions of the host- the bacteria that cause acne live in oil glands and feed off the oil produced by these glands. Bacterial growth causes pimples and blackheads

BACTERIAPathogenic

3. By secreting toxins that cause illness in the host.

• Staph. aureus causes food poisoning

• Clostridium botulinum release toxins that affect nervous system (Botulism)

• E. coli 0157:H7 is found in raw or improperly cooked meat.

• Good news! Most bacteria are killed by boiling water, hot, soapy water, (washing hands) or by cooking food properly.

BACTERIAThe Good Guys

1. Decay: without the actions of bacteria, most organic material would not decay, and there would be no recycling of nutrients in the ecosystem

2. Food Production: Yogurt. Many foods a product of fermentation (pickles, buttermilk, cheese, sourdough bread)

BACTERIAThe Good Guys

3. Industrial uses: production of acetone and butanol for use in the production of other chemicals

4. Mining: reduce the amount of waste produced from certain ores. Also to convert sulfur in ore, leaving the desirable mineral behind

5. Environmental: Cleaning up oil spills