AP Biology 2007-2008 Prokaryotes Domain Bacteria Domain Archaebacteria Domain Bacteria Domain Archaea Domain Eukarya Common ancestor
AP Biology 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 Microbes always find a way to make a living!
AP Biology Bacterial diversity rods and spheres and spirals… Oh My!
AP Biology Prokaryote Structure 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 chromosome, naked DNA not wrapped around proteins prokaryote cell eukaryote cell
AP Biology Prokaryote vs. Eukaryote Chromosome double helix Prokaryote Eukaryote
AP Biology The typical prokaryotic genome Is a ring of DNA that is not surrounded by a membrane and that is located in a nucleoid region Some species of bacteria Also have smaller rings of DNA called plasmids 1 m Chromosome
AP Biology Many prokaryotes form endospores Which can remain viable in harsh conditions for centuries Endospore 0.3 m Figure 27.9
AP Biology Variations in Cell Interior internal membranes for photosynthesis like a chloroplast (thylakoids) internal membranes for respiration like a mitochondrion (cristae) aerobic bacterium mitochondria cyanobacterium (photosythetic) bacterium chloroplast
AP Biology The cell wall of many prokaryotes Is covered by a capsule, a sticky layer of polysaccharide or protein 200 nm Capsule Figure 27.4
AP Biology Motility Most motile bacteria propel themselves by flagella Which are structurally and functionally different from eukaryotic flagella Many exhibit taxis, the ability to move towards or away from certain stimuli Flagellum Filament Hook Cell wall Plasma membrane Basal apparatus 50 nm Figure 27.6
AP Biology 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
AP Biology Obligate aerobes Require oxygen Mycobacterium tuberculosis Facultative anaerobes Can survive with or without oxygen Bacillus anthracis Obligate anaerobes Are poisoned by oxygen Clostridium botulinum
AP Biology Cooperation between prokaryotes Allows them to use environmental resources they could not use as individual cells In the cyanobacterium Anabaena Photosynthetic cells and nitrogen-fixing cells exchange metabolic products Photosynthetic cells Heterocyst 20 m
AP Biology Archaea Archaea share certaintraits with bacteria And other traits with eukaryotes Table 27.2
AP Biology Extreme thermophiles Very hot environments Methanogens Swap and marshes Produce methane as a waste product Extreme Halophiles High saline environments Figure 27.14 Some Archea live in extreme environments
AP Biology 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 to ammonia Bioremediation Remove pollutants from the environment help in digestion (E. coli): Symbiosis digest cellulose for herbivores cellulase enzyme produce vitamins K & B 12 for humans produce foods & medicines from yogurt to insulin