The Tree of Life All living things classified in three domains: –Bacteria –Archaea –Eukarya
Amazing Living Things Microbes indispensable to life: Produce much of Earth’s: Oxygen Decomposition Over half of Earth’s biomass More bacterial cells than human cells in your body!
Prokaryotes Prokaryotes have: –Circular DNA, 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
Prokaryotic DNA The area that contains the genetic material is referred to as the nucleoid. The genes are usually in one continuous circular loop of DNA. There may be other small circles of DNA outside the nulceoid called plasmids.
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: 90-106 o C –Aerobes and anaerobes
Some Prokaryotes Thrive in Extreme Conditions Cyanobacteria in Yellowstone Hot Springs
Archaea Unique lipid membranes, cell walls, and rRNA Methanogens – Convert CO 2 to methane – Swamps, hot springs, vent communities, cow stomachs Halophiles - survive concentrated salt environment Thermoacidophiles - thrive in hot, acidic environment Generally in EXTREME environments
Bacteria Evolve Rapidly Most of the time are asexual Classified by shape, locomotion, pigments, nutrients, colonies
Bacteria - Reproduction Binary fission: – Very fast, up to once every 20 minutes – One bacterium-> 10 21 in 24 hours. Conjugation : (sexual reproduction) – Used only occasionally.
Bacteria – Sexual Reproduction Conjugation: –G–Genetic variation through pili (structures similar to flagella) and plasmid DNA –D–DNA is exchanged between bacterial cells –O–Occurs through a special large, hollow pilus –O–One bacterium acts as a donor, transferring DNA to the recipient.
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
Transmission of Bacterial Pathogens Airborne Water Food Direct (skin contact, blood, and other body fluids) Insect vectors and other hosts such as deer tick (Lyme) or mosquito.
Germ Theory of Disease Theory that microorganisms are the cause of disease. 1859 – 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
Infectious Diseases Average age of death, in first world countries, jumped 30+ years in last century due to antibiotics, and 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!