BIO 3124 Lecture Notes - Lecture 5: Phagocytosis, Disaccharide, Magnetite
Document Summary
High surface area:volume ratio: favours diffusion and absorption (nutrient uptake and waste elimination) Allows there to be a concentration difference of some compounds. Allows there to be a different interior vs. exterior overall solute concentration. Allows the excretion of waste products - prevents them from coming back in. Composed of amphipathic phospholipids (both hydrophilic and hydrophobic) One layer is exposed to water - usually hydrophilic groups (phosphate groups in this case) Hydrophobic fatty acid chains of the phospholipids interact with one another to avoid water. Can have integral, amphipathic transmembrane proteins or hydrophilic, peripheral proteins. *maintains a hypertonic environment - all bacterial cells with a cell wall cain maintain a hypertonic environment: hypertonic: high solute concentration inside when compared to outside - less water inside than outside. Problem: goes against the concentration gradient - higher concentration inside. The more polar a compound, the more impermeable it is. Passage of molecules through the membrane without an investment of energy.
