Bacteria & Viruses

4 Ways to Identify Bacteria Shape Cocci Bacillus Spirochete

Cell Wall Peptidoglycan – in bacteria cell wall Gram (+) Purple Gram (-) Red

Flagella Slime Layer None Movement Flagella Slime Layer None

Oxygen Needs of Bacteria Oxygen at top Facultative Anaerobe Obligate Aerobe Obligate Anaerobe

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 Capsid DNA or RNA

Lytic Cycle of a Virus

Lysogenic Cycle of a Virus

How Vaccines Work

Retroviruses Have RNA which needs Reverse Transcriptase to convert into DNA and then added into host DNA for replication of virus

Prions – Infectious Proteins when eaten target specific tissues such as the brain Mad Cow Disease Scrapies in Sheep