Bellas Microbiology Exam II
Prokaryote Characteristics - ANS: - No membrane surrounding their DNA; no nucleus
- Lack organelles - internal membrane-bound structures
- Small; ~1.0 Ī¼m in diameter (RBC ~10 Ī¼m)
- Simple structure
QUIZ: Prokaryote Types - ANS: Bacteria & Archaea
QUIZ: Prokaryote External Structures (3) - ANS: Glycocalyces, Flagella and Fimbrae &
Pilli
QUIZ: Gycocalyx - ANS: "Sugar cage" - Polysaccharides
- Capsule & Slime Layer
QUIZ: Capsule - ANS: Hard glycocalyx with consistent structure around prokaryote
QUIZ: Slime Layer - ANS: Inconsistent outsider layer loosely attached to cell surface;
water soluble; protects cells form druing out; sticky layer that allows prokaryotes to
attache to surfaces
QUIZ: Flagella - ANS: Long, whiplike structures that extend beyond surface of cell and
is responsible for movement
QUIZ: Flagella Structure - ANS: - 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
QUIZ: Flagella Function - ANS: - Rotation propels bacterium through environment
- Rotation can be clockwise or counterclockwise; quickly reversible
- Prokaryotes move in response to stimuli (taxis)
QUIZ: Runs - ANS: movement of cell in singel direction for some time; increase with
favorable stimuli - chemotaxis or phototaxis
QUIZ: Tumbles - ANS: - abrupt, random, changes in direction; increase with
unfavorable stimuli: negative chemotaxis - away fr chemical or negative phototaxis -
away fr sunlight
- no steering mechanism
QUIZ: Fimbrae & Pili - ANS: Nonmotile extensions of prokaryotes
QUIZ: Fimbrae - ANS: - Sticky, proteinaceous, bristlelike projections
- Used by bacteria to adhere to one another, to hosts, and to substances in environment
------
- May be hundreds per cell and are shorter than flagella
