Key Terms
Early Earth
Anoxic atmosphere, intense radiation, volcanic activity. First prokaryotes were thermophiles adapted to heat.
Microbial mats
Multi-layered sheets of prokaryotes (mostly bacteria, some archaea) held together by secreted extracellular matrix. Foss
Stromatolites
Fossilized microbial mats. Layered sedimentary structures formed when minerals precipitate out of water due to prokaryot
Extremophiles
Prokaryotes adapted to grow optimally under harsh conditions. Many cannot survive in moderate environments.
Viable-but-non-culturable (VBNC) state
A dormant survival state triggered by environmental stress. The organism is alive but will not grow on lab media.
To detect non-culturable prokaryotes
Use PCR to amplify 16S rRNA gene sequences from environmental samples. Demonstrates presence without needing to culture
Robert Koch
Developed pure culture techniques, staining, and growth media. His postulates identify disease-causing organisms: the pa
Biofilm
A microbial community attached to a surface, held together by an extracellular polysaccharide matrix (EPS). Most prokary
Five stages of biofilm development
1. Initial attachment via weak van der Waals forces 2.
Found everywhere
Pipes, food-processing equipment, kitchen surfaces, teeth (dental plaque), medical devices, open wounds. Responsible for
Three basic cell shapes
Cocci (spherical), bacilli (rod-shaped), spirilli (spiral-shaped).
Plasma membrane
Thin lipid bilayer, 6-8 nanometers thick. Selectively permeable.
Cell wall
Located outside the plasma membrane. Prevents osmotic lysis.
Capsule
Found in some species; outside the cell wall. Functions: attachment to surfaces, protection from dehydration, protection
Flagella
Used for locomotion. Pili (singular: pilus): used for attachment to surfaces and other cells; also used in conjugation.