Bacteria The microscopic world Chaper 15 pp

K. Archaebacteria Archae = “ancient” –Common ancestor to all life “extreme” bacteria –Halophiles –Thermoacidophiles – methanogens K. Eubacteria Eu – “true” or NEWer bacteria Commonly found Pathogenic & beneficial Bacteria - Two Kingdoms of unicellular, prokaryotes

Classified by shape & clustering

Bacterial cell morphology

Bacterial Plaque

Morphology Gram positive bacteria - HOLD stain b/c of thick cell wall (purple) Gram negative – REPEL stain (pink) due to thin cell wall & thick layer of lipopolysaccharide

Nutrition & Niche Heterotrophs –chemiotrophs –Saprophytes Autotrophs –Photosynthetic

Reproduction & Growth Asexual- binary fission Doubling time every 20 minutesDoubling

Changes to Bacterial DNA - conjugation

How do they cause harm? Exotoxins Endotoxins Both work b/c enzyme destruction of tissue –Attachment of bacteria to cell, enzymes “digest” cell –Disrupt metabolism/homeostasis

Bacterial longevity Ability to persist, wait for ideal conditions –Endospores

Control of Bacteria Prevent entry to body –Hygiene, pasteurization, antiseptics, vector control, CONDOMS Prevent growth or kill –Antibiotics Antibiotic resistance the new concern

Phylum Cyanobacteria Photosynthetic – raised earth’s early oxygen levels Heterocysts to fix atmospheric N Feed on phosphates and nitrates in fertilizers Eutrophication caused by sudden growth of cyanobacteria

Phylum Spirochetes Move by corkscrew-like movement Live freely, symbiotically or parasitically –Treponema pallidum – syphilis –Borrelia burgdorferi - Lyme disease

Phylum Gram-Positive Bacteria Helpful and harmful + and - bacteria produce yogurt (lactic acid produced in milk) Lactobacilli – tooth decay Pathogenic – Streptococci, Staphylococcus, Antibiotics formed - Actinomycetes

Phylum Proteobacteria Enteric bacteria –Found in intestines –Escherichia coli (E. coli), Salmonella Chemoautotrophs –Feed on minerals Nitrogen fixing bacteria –Symbiotic with plants or free living in soil –Rhizobium, Azotobacter

CommonCommon bacterial Diseases

Helpful bacteria

Bacteria pathogensbeneficial