BRAINCAKECell Surface Membrane
Like all cells, a bacterium has a cell surface membrane (plasma membrane). It lies just inside the cell wall and surrounds the cytoplasm.
Structure
The bacterial membrane has the same basic fluid mosaic structure as eukaryotic membranes: a phospholipid bilayer containing intrinsic and extrinsic proteins. A difference is that bacterial membranes usually contain no cholesterol.
Functions
• Controlling entry and exit: the membrane is partially permeable. Channel and carrier proteins control the movement of ions, sugars, amino acids and waste products by diffusion, facilitated diffusion and active transport. The cell wall, by contrast, is freely permeable.
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Key terms in this lesson
- cyanobacteria
- Photosynthetic prokaryotes that carry out photosynthesis using chlorophyll held on internal membranes, since they have no chloroplasts.
More in Prokaryotic Cells
- Bacterial Cell
- Pili and Flagella
- Plasmids
- Nucleoid
- 70S Ribosomes
- Gram-Staining
- Antibiotics
- Alternative Classification of Bacteria
All 31 lessons in Prokaryotic Cells · All Edexcel AS-level Biology topics