Bacteria &

Viruses

4 Ways to Identify Bacteria

1. Shape

Cocci Bacillus Spirochete

2. Cell Wall

Peptidoglycan – in bacteria cell wall

• Gram (+) Purple Gram (-) Red

3. Movement

Flagella Slime Layer None

4. How they get their energy

• Photoautotroph

• Chemoautotroph

• Heterotroph

• Photoheterotroph

Bacterial Reproduction & Growth

Binary Fission Conjugation

Oxygen Needs of Bacteria

Facultative Anaerobe Obligate Aerobe Obligate Anaerobe

Oxygen at top

Nitrogen FixationProcess where bacteria on plant roots convert

nitrogen gas in the air into ammoniaNitrogen is necessary for proteins and nucleic acids

Mutualism!Both plant and bacteria benefit

Human uses for bacteria

Pathogens – Bacteria that cause disease

Two Ways Bacteria Cause Disease

• Produce Toxins (Food poisoning)

• Damage Tissue

Controlling Bacterial Growth

• Antibiotics – Slows growth; does not kill bacteria

• Disinfectants – Chemical that kills bacteria

• Sterilization – Heat, pressure, gas that kills bacteria

• Refrigeration – Slows growth; does not kill bacteria

• Canning – High heat to kill bacteria• Chemical Treatments –

Preservatives in food; slows growth; does not kill

Virus – Obligate Parasite – Must have a host to survive and multiply

DNA or RNACapsid

Lytic Cycle of a Virus

Lysogenic Cycle of a Virus

How Vaccines Work

Oncogenic Viruses Disrupt cyclins that regulate cell growth

Retroviruses

Have RNA which needs ReverseTranscriptaseto convert into DNA and then added into host DNA for replication of virus

Prions – Infectious Proteins when eaten target specific tissues such as the brainMad Cow DiseaseScrapies in Sheep