Bacteria
Our invisible friends
Bacteria are prokaryotes
Pro – before
Karyon – nucleus
The simplest forms of life are
prokaryotes.
Earth’s first cells were
prokaryotes.
Lots of Them!
Prokaryotes are Earth’s most
abundant life forms.
They can survive in many
environments.
They can get energy from many
different sources.
Prokaryote Review
 Mostly single-celled
 No nucleus or organelles
 Circular chromosomes
 Cell walls
 Reproduce mostly asexually
 Anaerobic or aerobic
 Heterotrophic or autotrophic
Archaebacteria
Methane producers – anaerobic
Halophiles
Halo = salt
 Philia = love

Thermophiles

Thermo = heat
Eubacteria
 Parasitic heterotrophs (Streptococcus)
 Saprophages
Sapro = death
 Phage = eat

 Cyanobacteria (blue-green algae)

Photosynthetic
 Chemosynthetic autotrophs (Rhizobium)
Bacteria are Named by Shape
Cocci (ball-shaped)

Streptococcus mutans
Bacillus (rod-shaped)

Clostridium botulinum
Spirilli (spiral-shaped)

Treponema palladium
Germ Theory of Disease
Joseph Lister – Aseptic
Techniques
Robert Koch – Germ Theory

A specific microorganism causes
a specific disease