Chapter 10

Bacteria & Viruses

Chapter 10A

Bacteria

Characteristics of Bacteria

• Very small, but largest in number

• Hard to study• Can live almost anywhere• Prokaryotic

Microbiology

The study of microbes (organisms that require a microscope to be seen)

Most bacteria are pathogenic (cause

disease).1. True2. False

Pathogenic: causing disease; bacteria and viruses

Decomposers: organisms that break down organic substances; bacteria and fungi

Kingdom Archaebacteria

• Cell walls DO NOT contain peptidoglycan

• “Extremophiles”–Thermoacidophiles–Methanogens–Halophiles

Kingdom Eubacteria• The larger kingdom• Contains the bacteria

people are most familiar with

• Cell walls DO contain peptidoglycans

• Very diverse

Bacterial Shapes• Coccus: spherical• Bacillus: rod-shaped• Spirillum: spiral-shaped

Uses of Bacteria• Most bacteria are NOT

pathogenic. • Used in making cheese,

yogurt, sauerkraut, and buttermilk

• Form alcohol, lactic acid, and vinegar through fermentation

Uses of Bacteria• Used in tanning leather and

forming silage• Help break down food in the

intestines• Source of antibiotics

Uses of Bacteria• Through genetic engineering

techniques, bacteria can be used to produce:–human insulin–blood proteins–other substances

Uses of Bacteria• Bacteria and fungi are the

primary decomposers in nature.

• The process of bioremediation uses bacteria to break down harmful substances in the environment.

Structure of a Bacterial Cell

• Prokaryotic• Plasma (cell) membrane• Cell wall

–Peptidoglycans–Gram’s staining

• Capsule

Structure of a Bacterial Cell

• Nuclear area• Plasmids• Mesosomes• Ribosomes• Flagella

Reproduction is by simple binary

fission that does NOT involve

mitosis.

BACTERIALREPRODUCTION AND GROWTH

Transfer of Genetic Material

• Conjugation• Transformation• Transduction

Bacteria and Nutrition• Autotrophic (some

bacteria)–Photosynthetic–Chemosynthetic

(converting inorganic compounds into usable forms)

Bacteria and Nutrition• Heterotrophic (most

bacteria)–Saprophytic–Parasitic

• Obligate parasites

Bacteria and NutritionHeterotrophi

cAutotrophi

cParasiticSaprophyti

cPhotosyntheti

cChemosynthe

tic

Conditions for Bacterial Growth

• Moisture• Temperature• pH• Nutrition

Endospores: special spores produced

by some bacteria that allow them to survive long periods of unfavorable growing conditions

Ex: the bacterium that causes anthrax

Bacteria and Oxygen• Obligate anaerobes • Obligate aerobes• Facultative anaerobes

Other Bacteria• Rickettsiae

–Intracellular parasites

–Typhus fever–Rocky Mountain spotted fever

Other Bacteria• Spirochetes

–Larger than most bacteria

–Many are corkscrew-shaped

–Lyme disease

Other Bacteria• Mycoplasmas

–No cell wall–Some types of pneumonia, arthritis, and urinary tract infections