The evolutionary tree of life can be documented with evidence. Bacteria Archae- bacteria Animalia Fungi Protista Plantae 4500 4000 3500 3000 2500 2000 500 1500 1000 Formation of earth Molten-hot surface of earth becomes cooler Oldest definite fossils of prokaryotes Appearance of oxygen in atmosphere of eukaryotes First multicellular organisms Appearance of animals and land plants Colonization of land by animals Paleozoic Mesozoic Cenozoic Millions of years ago ARCHEAN PRECAMBRIAN PROTEROZOIC The evolutionary tree of life can be documented with evidence. Fossils Genetics Physiology

Archaebacteria & Bacteria Eukaryote Prokaryote Classification Old 5 Kingdom system Monera Protists Plants Fungi Animals Archaebacteria & Bacteria

Classifying Life Molecular data challenges 5 Kingdoms Monera was too diverse 2 distinct lineages of prokaryotes Protists are still too diverse not yet sorted out

3 Domain system Domains = “Super” Kingdoms Bacteria Archaea Eukarya extremophiles = live in extreme environments methanogens halogens thermophiles Eukarya eukaryotes protists fungi plants animals

Kingdom Archaebacteria Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia Kingdom Archaebacteria Kingdom Bacteria

Domain Bacteria Domain Archaebacteria Prokaryotes Domain Bacteria Domain Archaebacteria Domain Bacteria Archaea Eukarya Common ancestor

Bacteria live EVERYWHERE! Bacteria live in all ecosystems on plants & animals in plants & animals in the soil in depths of the oceans in extreme cold in extreme hot in extreme salt on the living on the dead

Bacterial diversity rods and spheres and spirals… Oh My! Rods Spheres

Prokaryote Structure Unicellular Size Internal structure eukaryote cell Prokaryote Structure prokaryote cell Unicellular bacilli, cocci, spirilli Size 1/10 size of eukaryote cell 1 micron (1um) Internal structure no internal compartments no membrane-bound organelles only ribosomes circular, naked DNA not wrapped around proteins

Variations in Cell Interior cyanobacterium (photosythetic) bacterium aerobic bacterium internal membranes for photosynthesis like a chloroplast (thylakoids) internal membranes for respiration like a mitochondrion (cristae)

Prokaryote Cell Wall Structure peptide side chains cell wall peptidoglycan plasma membrane protein Gram-positive bacteria peptidoglycan = polysaccharides + amino acid chains lipopolysaccharides = lipids + polysaccharides Gram-negative bacteria peptidoglycan plasma membrane outer outer membrane of lipopolysaccharides cell wall

Prokaryotic metabolism How do bacteria acquire their energy & nutrients? photoautotrophs photosynthetic bacteria chemoautotrophs oxidize inorganic compounds nitrogen, sulfur, hydrogen… heterotrophs live on plant & animal matter decomposers & pathogens

Genetic variation in bacteria Mutations bacteria can reproduce every 20 minutes binary fission error rate in copying DNA 1 in every 200 bacteria has a mutation Genetic recombination bacteria swap genes plasmids small supplemental circles of DNA

Genetic variation in bacteria Transformation Taking in DNA from the environment Cell surface receptors recognize closely related DNA and take it in! Griffith experiment, showing genetic material could be transferred

Genetic variation in bacteria Transduction Bacteriophages Specialized viruses that infect bacteria only Take DNA from one bacteria to another Like a mosquito carrying a parasite

Genetic variation in bacteria Conjugation Two bacteria are temporarily joined by a pilus One way only

Bacteria as pathogens Disease-causing microbes plant diseases wilts, fruit rot, blights animal diseases tooth decay, ulcers anthrax, botulism plague, leprosy, “flesh-eating” disease STDs: gonorrhea, chlamydia typhoid, cholera TB, pneumonia lyme disease

Bacteria as beneficial (& necessary) Life on Earth is dependent on bacteria decomposers recycling of nutrients from dead to living nitrogen fixation only organisms that can fix N from atmosphere needed for synthesis of proteins & nucleic acids plant root nodules help in digestion (E. coli) digest cellulose for herbivores cellulase enzyme produce vitamins K & B12 for humans produce foods & medicines from yogurt to insulin

Any Questions??