Bacteria Our invisible friends

Bacteria Bacteria are microscopic organisms that are prokaryotes.

Bacteria are prokaryotes Pro – before Karyon – nucleus The simplest forms of life are prokaryotes. Earth’s first cells were prokaryotes.

Bacteria Prokaryotes are divided into two domains: 1. Eubacteria 2. Archaebacteria

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

Eubacteria Very strong cell walls Contain peptidoglycan Some have a second cell wall

Eubacteria Parasitic heterotrophs (Streptococcus) Saprophages Sapro = death Phage = eat Cyanobacteria (blue-green algae) Photosynthetic Chemosynthetic autotrophs (Rhizobium)

Archaebacteria Methane producers – anaerobic Halophiles Thermophiles Halo = salt Philia = love Thermophiles Thermo = heat

Prokaryote Structure

Prokaryote Structure Prokaryotes are microscopic, unicellular organisms. They have some characteristics of all cells, such as DNA and ribosomes. Lack a nuclear membrane and other membrane-bound organelles

Bacteria are Named by Shape Cocci (ball-shaped) Streptococcus mutans Bacillus (rod-shaped) Clostridium botulinum Spirilli (spiral-shaped) Treponema palladium

Shapes Cocci Bacilli Spirochetes

Movement Prokaryotic flagella are made of filaments. Flagella help prokaryotes to move toward materials that they need to survive.

Germ Theory of Disease Joseph Lister – Aseptic Techniques Robert Koch – Germ Theory A specific microorganism causes a specific disease