Microbiology Lecture 4
- Created by: emmawilliams
- Created on: 05-04-17 15:17
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Bacteria
Cell size
Size range for prokaryotes: 0.2 µm to >700 µm in diameter
Most cultured rod-shaped bacteria are between 0.5 and 4.0 µm wide and <15 µm long
Cell morphology
Morphology = cell shape
Major cell morphologies:
- Coccus (pl. cocci): spherical or ovoid
- Bacillus (pl. bacilli): rod or cylindrical shape
- Spirillum (pl. spirilla): spiral shape
Cells with unusual shapes: Spirochetes, appendaged bacteria, and filamentous bacteria
Many variations on basic morphological types
Cytoplasmic membrane:
- Thin structure that surrounds the cell
- 6–8 nm
- Vital barrier that separates cytoplasm from environment
- Highly selective permeable barrier; enables concentration of specific metabolites and excretion of waste products
Function
Permeability Barrier
- Polar and charged molecules must be transported
- Transport proteins accumulate solutes against the concentration gradient
Protein Anchor
- Holds transport proteins in place
Energy Conservation
The bacterial cell wall
Peptidoglycan
Rigid layer…
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