Bacteria

Pathetic Microbe Games

Archaebacteria Live in extreme locations: Oxygen-free environments Concentrated salt-water Hot, acidic water

Classification (Shape) Spheres = cocci Rods= bacilli Spirals= spirilla Arrangement: Chain = Strepto Cluster = Staphylo Pair = diplo

Classification (Oxygen) Obligate anaerobe: cannot live in the presence of oxygen. Obligate aerobe: must have oxygen to survive. Facultative aerobe: can live with or without oxygen.

Classification by Energy Source Heterotrophs Requires an external source of food Photosynthetic autotrophs Make food from light Chemosynthetic autotrophs Make food from chemicals (sulfur, nitrogen)

Movement in Bacteria Some have one or more flagella (long, whip-like structures) Some have cilia (short, hair-like structures). Some don’t move.

Structure of Bacteria DNA is loose in the cytoplasm. Ribosomes Outside the membrane is a cell wall Some have an outer capsule

Other Structures Pili Capsule Plasmid Protein appendages Used in conjugation Adhere bacteria to surfaces Capsule Plasmid Extra circle of DNA

Reproduction Binary fission: (asexual) DNA replicates and the cell divides Conjugation: (sexual) DNA is transferred from one bacterial cell to another through pili. spores: specialized cell with a thick, protective wall. Produced under harsh conditions. Very difficult to destroy.

Growth Grow very rapidly: some double every 20 minutes What bacteria need to grow: nutrients Space Temperature Moisture

What Kills Bacteria? Antibiotics UV radiation Salinity Heat pH (acidic or alkaline)

Antibiotics Kill bacteria, do not harm human cells Some destroy bacteria (damage cell wall). Some slow bacteria growth (inhibit DNA synthesis) Do not work on viruses

Antibiotic Resistance Bacteria that are resistant to an antibiotic survive, reproduce. Caused by: overuse (used for minor infections) underuse (don’t complete antibiotic treatment) misuse (used when not needed)

1. A bacterium carries genes for antibiotic resistance. 2. Genes are transferred through conjugation. 3. Resistant bacteria survive and reproduce (make more resistant bacteria)

Benefits of Bacteria Break down or decompose wastes. Nitrogen fixation. Used to digest food. Clean up oil spills. Make yogurt and cheese. Fight disease-causing bacteria.