prokaryotes - simplest organisms
- 2 main groups - archaebacteria, bacteria
- no distinct interior compartments
- perform photosynthesis, break down dead organisms, cause diseases
cell wall - surrounds most prokaryotic cells
- peptidoglycan - sugar polymers cross-linked by polypeptides; found in bacteria walls
- protects cell, maintains shape, prevents overdose of water
- gram-positive bacteria - have thick, single-layered cell wall; turns purple from gram staining
- gram-negative bacteria - more complex bacteria w/ multilayered cell wall; doesn't turn purple, turns red
- drugs often destroy bacteria's cell wall to kill it
- disease-causing bacteria secrete a jellylike capsule of polysaccharides to allow it to cling to different surfaces
flagellum - long threadlike structure used by some prokaryotes to move
- protein fibers extending from the bacteria cell
- could be more than 1 per cell, depending on the species of bacteria
- rotated like a screw to propel the cell forward
- uses proton gradient on the membrane to power the flagellum's mov't (process also used by some enzymes that produce ATP in mitochondria/chloroplasts)
prokaryotic interior organization - very simple, no membrane-bounded organelles
- no interior support >> prokaryotic cell's strength depends on cell wall
- membrane performs much of the tasks done by organelles in eukaryotes
- prokaryote acts as a single unit (no specific task done only at a specific area)
eukaryotes - much more complex than prokaryotes
- compartmentalization possible through endomembrane system and organelles
- vesicles - sacs that store/transport certain materials
- chromosomes - compact units of DNA
- cytoskeleton - internal protein support for the cell
- animals and some protists lack cell walls
- central vacuole - large sac holding proteins, pigments, waste in plants
Animal Cell
Plant Cell
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