BIOL 1202 : Exam 2
Document Summary
Microbes too small to be seen clearly without a microscope (light or electron microscope) 1/1,000,000 of a meter; the period at end of sentence is about 1000 um. Far less than 1% of all bacterial species cause human disease (pathogens). Viruses are much smaller than most bacterial cells and eukaryotic cells. 12,000 species described, may be 100-1000x that number. 1st organisms to appear on earth, 3. 9-4. 1 billion years ago. The first organisms on earth were most similar to today"s bacteria (prokaryotes). Cell membrane lipid structure (use different types of lipids) Cell wall composition (bacteria use peptidoglycan, a polymer of sugar; archaea don"t) rrna subunit sequences (different type of rrna) Composed of (peptidoglycan carbohydrate with amino acids attached) Gram positive/negative bacterial cells based on the amount of peptidoglycan) Capsules = highly organized, firmly attached to cell wall. Slime layers = less organized, loosely attached to cell wall.
