Chapter 18 - Bacteria

Bacterial Structures DNA Ribosomes Cell wall Flagellum Pili

Gram Stain Gram positive Gram negative

Bacteria Shape Cocci (coccus) Bacilli (bacillus) Spirilla (spirillum)

Diplo – pairs Staphylo – clusters Strepto – chains

Streptococcus

Movement & Support Have cell walls to support shape and provide protection Some have flagellum for movement

Digestion/Obtaining Nutrients Some are autotrophs Photosynthetic Chemosynthetic Some are heterotrophs that use organic molecules that they engulf & breakdown Some use aerobic respiration and others use fermentation (anaerobic). These processes produce energy

Nervous/Response Circular chromosome with DNA Some produce endospores Some produce toxins

Circulation Rely on flow of cytoplasm to move materials through cell

Gas Exchange Gases are exchanged directly to the environment through diffusion

Excretion Waste is secreted through the cell membrane by diffusion or exocytosis

Reproduction Asexual – binary fission Sexual – conjugation through pilus

What makes bacteria so great? They reproduce rapidly Their DNA mutates frequently They can exist in extreme environments They are able to use substances that other organisms cannot

Helpful Bacteria Nitrogen fixation Recycling nutrients (saprophytes & decomposers) Medicine Food

Harmful Bacteria E. coli Salmonella Bacillus anthracis Yersinia pestis Staphylococcus aureus

Antibiotic Resistance

Vaccines & Immunity Vaccines consist of dead/destroyed virus or bacteria Sensitizes the body to the foreign objects Creates antibodies that recognize foreign antigen Allows the body to react more quickly when it encounters the “real deal”

How do we protect ourselves from infectious agents? Skin Body secretions Inflammation & fever Antibodies Antibiotics & vaccines