BIO 101 Lecture Notes - Lecture 19: Cyanobacteria, Viroid, Tuber
Document Summary
Chapter 19: the diversity of prokaryotes and viruses. Prokaryotes: earth"s first organisms, single-celled microbes that lacked organelles. They are still abundant, forming two of life"s three domains: bacteria and archaea. They are very hard to tell the difference externally, it"s their biochemical production that is different. 3 common prokaryotic shapes: coccus (spherical), bacillus (rod-shaped), spirilla (cork-skew) Prokaryote flagellum: cell wall, well and axle base - have the ability to rotate, don"t actually have an axel, peptidoglycan layer, outer membrane, plasma membrane. Many bacteria form films on surfaces: some bacteria secrete sticky layers of polysaccharide or protein slime, biofilms: aggregates (communities) of slime-secreting bacteria. Bacteria are embedded in biofilms and protected from disinfectants and antibiotics ie. dental plaque -> tooth decay. Protective endospores allow some bacteria to withstand adverse conditions: endospores: thickly wrapped particles of genetic material and a few enzymes. They form inside some bacteria under inhospitable environmental condition. When they form, the bacterium breaks open and releases them.
