Prokaryotes And The Origins of Metabolic Diversity Kingdom Monera

The Oldest Organisms Oldest fossils go back 3.5 bya Chemical cycles evolved in prokaryotes Wide range of modes of nutrition Est. diversity of up to 4 million species Two main brances are archaea and bacteria

The Three Domains

Comparing Domains CHARACTERISTICS BACTERIAARCHAEAEUKARYA Peptidoglycan in cell wall PresentAbsent RNA PolymeraseOne kind onlySeveral kinds Initiator amino acid in protein synthesis Formyl-methionineMethionine Histones associated with DNA NonePresent Introns in genesNoneSomePresent

Three Common Shapes Spheres - CocciRods - Bacilli Helices – Spirilla, spirochetes

Classification By Gram Stain

Gram Positive and Gram Negative Bacteria

Pilli Allow bacteria to attach to a substrate Allow for exchange of plasmids during conjugation Not present in all bacterial groups

Some Bacteria Are Motile Bacilli may move using one or more flagella Narrower than eukaryotic flagella Lack membrane covering Not a 9+2 pattern Exhibit taxis: chemo or photo

Flagella

Reproduction and Genetic Recombination Asexual reproduction by binary fission – 20min. in log phase growth Three mechanisms of genetic recombination: 1. transformation 2. conjugation 3. transduction Mutation is the major source of genetic variation

Bacilli Produce Endospores Bacillus anthracis Resistant capsule Survives many attempts destroy it Requires sterilization with heat and pressure: Steam at 15 lbs. per sq. in. for at least 20 min.

Nutrition and Metabolic Diversity Mode of NutritionEnergy Source Carbon Source Type of Organism PhotoautotrophsSunlightCO 2 Cyanobacteria, certain protists (algae) ChemoautotrophsInorganic Chemicals (H 2 S, NH 3, Fe 2+ ) CO 2 Sulfur bacteria PhotoheterotrophsSunlightOrganic molecules Certain prokaryotes ChemoheterotrophsOrganic molecules Animals, fungi, many protists, prokaryotes, parasitic plants

Evolution of Photosynthesis

Archaea Methanogens – use CO 2 to oxidize H 2 into CH 4 Exteme halophiles: (Bacteriorhodopsin is their photosynthetic pigment. Purple color) Extreme thermophiles: Oxidize sulfur for energy at deep-sea thermal vents at 105ºC

Ecological Impact of Prokaryotes Decomposers: Recycle chemical elements between biological and physical components of the ecosystem Fix carbon (as CO 2 ) and nitrogen (as NH 3 ) Produce O 2 (cyanobacteria) Symbiotic: mutualism – cyanobacteria in root nodules commensalism – bacteria in/on the body parasitism – pathogenic bacteria Streptomyces – Source of our antibiotics

Koch’s Postulates 1.Find the same pathogen in each diseased individual. 2.Isolate pathogen from diseased individual and grow it in pure culture. 3.Induce disease using pure culture. 4.Re-isolate pathogen from individuals in which disease was induced from pure culture. ** Doesn’t work for all pathogens (Treponema pallidum, the cause of syphilis, can’t be cultured on media)

Exotoxins Proteins secreted by prokaryotes Clostridium botulinum – botulism (botox) Vibrio cholerae – Cholera (severe diarrhea) E. coli – Traveller’s diarrhea

Endotoxins Components of the outer membranes of certain gram-negative bacteria Genus Salmonella – Causes food poisoning Actinomycetes – Fungus-like prokaryotes 1. Mycobacterium sp. (Tuberculosis & leprosy) 2. Streptomyces sp. (Antibiotics)

Benefit to Society Remove pollutants from soil, water, or air Oil spills Sewage treatment Production of drugs by genetic engineering Prevention of freeze damage to crops Antibiotic production