2OutlinePrevalence of ProkaryotesProkaryotic DiversityProkaryotic ComplexityProkaryotic VariationProkaryotic MetabolismHuman Bacterial DiseasesBenefits of Prokaryotes
3Prevalence of Prokaryotes Prokaryotes are the oldest, structurally simplest, and most abundant forms of life on earth.abundant for over 2 billion years before the appearance of eukaryotes5,000 different kinds currently recognized
5Prevalence of Prokaryotes Prokaryotic formbacillus (bacilli) straight and rod-shapedcoccus (cocci) spherical shapedspirillum (spirilla) long and helical shapedSome bacterial colonies form spore producing structures.
6Prevalence of Prokaryotes Prokaryotes versus Eukaryotesunicellularitycell sizechromosomescell division and recombinationinternal compartmentalizationflagellametabolic diversity
7Prokaryotic Diversity Key classification characteristicsphotosynthetic or nonphotosyntheticmotile or nonmotileunicellular or colony-forming or filamentousspore formation by division or transverse binary fission
8Kinds of ProkaryotesVery early, prokaryotes split into two linesArchaea and bacteria are as different in structure and metabolism from each other as either is from eukarya.Domain Archaea
9Prokaryotic Diversity Comparing archaebacteria and bacteriaplasma membranescomposed of different lipidscell wallarchaebacteria lack peptidoglycangene translation machineryarchaebacteria similar to eukaryotesgene architecturebacteria not interrupted by introns
10Prokaryotic Complexity Prokaryotic cell surfacecell wall maintains shape and protects the cell from swelling and rupturingusually consist of peptidoglycanGram-positive - thicker peptidoglycanGram-negative - thinner peptidoglycanflagella – slender protein - locomotionpili - hairlike structures - attachmentendospores - resistant to environment
13The Cell InteriorInternal membranesinvaginated plasma membraneNucleoid regionlack nucleus - genes encoded with single double-stranded DNARibosomesProkaryotic ribosomes are smaller than eukaryotic ribosomes, and differ in protein and RNA content.
14Prokaryotic Variation Two process create bacterial variation:mutationspontaneous errors in DNA replicationprokaryotic ability to mutate rapidly often has adverse effect on humansgenetic recombinationoccurs by gene transfer from one cell to another by viruses or conjugation
16Prokaryotic Metabolism How heterotrophs infect host organismsproteins secreted by type III systemmay be used to transfer other virulence proteins into nearby eukaryotic cells
17Human Bacterial Diseases Tuberculosisafflicts respiratory system and easily transmitted from person to person through the airDental cariestooth decay caused by bacteria present in plaquehigh sugar diets increase tooth decaylactic acid bacteria ferment sugars and reduce pH, thus degenerating tooth enamel