BIOL 1500 Study Guide - Trichomonas, Syphilis, Symbiogenesis
Document Summary
Learning objectives: distinguish between bacteria, archaea and protists. Prokaryotic cell walls maintain cell shape, provide physical protection, and prevent the cell from bursting in a hypotonic environment. In a hypertonic environment, most prokaryotes lose water and shrink away from their wall. Bacterial cell walls can be distinguished with a gram stain. Gram-positive bacteria have simple walls with a thick layer of peptidoglycan. Gram-negative bacteria have complex walls with less peptidoglycan and an outer membrane of lipids bonded to carbohydrates. Explain how populations of prokaryotes can adapt rapidly to changes in their environment; explain how this has contributed to the success of prokaryotes. Some prokaryotes stick to the substrate or each other with hair-like appendages called pili. The flagella of bacteria and archaea allow them to move in response to chemical and physical signals in their environment. The prokaryotic flagellum is a naked protein without microtubules. Some prokaryotes can withstand harsh conditions by forming endospores within an outer cell.
