Prokaryotes: Archaea & Bacteria

The Tree of Life All living things classified in three domains:  Bacteria  Archaea  Eukarya

Amazing Living Things Microbes important to all life: DDecomposition OOver half of Earth’s biomass MMore bacterial cells than human cells in your body!

Prokaryotes Prokaryotes have:  DNA or RNA, ribosomes, cytoplasm, plasma membrane  Most prokaryotes have a cell wall, a capsule (around the cell wall) and a flagellum Prokaryotes don’t have:  Organelles such as nucleus, chloroplasts, mitochondria.

Generalized Prokaryote Capsule Cell Wall Plasma Membrane Cytosol Nucleoid DNA Flagellum Plasmid DNA

Bacteria/Archaea Habitats (name a place, and they live there!)  They are specialists human skin, mouth, respiratory tract, large intestine, urogenital tract, etc. salty Dead Sea extreme pH archea in deep sea vents: o C  Aerobes and anaerobes

Some Prokaryotes Thrive in Extreme Conditions Cyanobacteria in Yellowstone Hot Springs

Archaea Unique lipid membranes, cell walls, and RNA EXTREME Environments:  Swamps, hot springs, vent communities, cow stomachs  concentrated salt environments  hot, acidic environments

Bacteria Shape:  Cocci - round  Bacilli - rod  Spirilla - spirals

Three Common Bacterial Shapes (a) (b) (c) cocci spirillus bacillus

The Prokaryote Flagellum Bacterium Flagella

Bacteria Reproduction Reproduction is asexual, by simple splitting (binary fission) Daughter cells are genetic clones of the parent cell

Binary Fission DNA

Benefits of Bacteria Symbiosis (mutualism)  Ruminants’ digestive tracts  Nitrogen fixing in soil, nodules on certain legumes  Bacteria on/in the human body: intestines and vitamin K and B12 Biodegradation - oil Food production - cheese, yogurt, sauerkraut Decomposers

Our Relationship With Bacteria

Harmful Bacteria Some cause disease = pathogenic In humans: SStrep throat TToxins - tetanus, botulism PPneumonia ""Flesh-eating" bacteria PPlague TTuberculosis CCholera LLyme disease ANTIBIOTICS= anti bacterial!!!

The Causes of Tooth Decay

Transmission of Bacterial Pathogens Airborne Water Food Direct (skin contact, blood, and other body fluids) Insects and other hosts such as deer tick (Lyme).

Germ Theory of Disease Theory that microorganisms are the cause of disease – Louis Pasteur  Credited with the idea that human diseases were caused by bacteria and viruses (germ theory)  Very important discovery in the field of medicine  Also created vaccinations to prevent disease

Infectious Diseases Average age of death, in first world countries, jumped 30+ years in last century  due to antibiotics  enhanced hygiene and nutrition Antibiotic-resistant infections on the rise in hospitals in the U.S.  This is due to bacterial evolution in response to widespread use of antibiotics!