Bellas Microbiology Exam II With 100% Verified Solutions | Updated & Verified | 2024

Prokaryote Characteristics - - No membrane surrounding their DNA; no nucleus - Lack organelles - internal membrane-bound structures - Small; ~1.0 μm in diameter (RBC ~10 μm) - Simple structure Prokaryote Types - Bacteria & Archaea Prokaryote External Structures (3) - Glycocalyces, Flagella and Fimbrae & Pilli Gycocalyx - "Sugar cage" - Polysaccharides - Capsule & Slime Layer Capsule - Hard glycocalyx with consistent structure around prokaryote Slime Layer - Inconsistent outsider layer loosely attached to cell surface; water soluble; protects cells form druing out; sticky layer that allows prokaryotes to attache to surfaces Flagella - Long, whiplike structures that extend beyond surface of cell and is responsible for movementFlagella Structure - - Composed of filament, hook, and basal body - Flagellin protein (filament) arranged in chains and forms helix around hollow core - Base of filament inserts into hook Flagella Function - - Rotation propels bacterium through environment - Rotation can be clockwise or counterclockwise; quickly reversible - Prokaryotes move in response to stimuli (taxis) Runs - movement of cell in singel direction for some time; increase with favorable stimuli - chemotaxis or phototaxis Tumbles - - abrupt, random, changes in direction; increase with unfavorable stimuli: negative chemotaxis - away fr chemical or negative phototaxis - away fr sunlight - no steering mechanism Fimbrae & Pili - Nonmotile extensions of prokaryotes Fimbrae - - Sticky, proteinaceous, bristlelike projections - Used by bacteria to adhere to one another, to hosts, and to substances in environment