Cell Membrane and Cell Transport Notes PDF
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Summary
These notes cover the structure and function of the cell membrane, including its role in regulating the entry and exit of substances. Key concepts include the fluid mosaic model and the different mechanisms of cell transport, such as simple diffusion, facilitated diffusion, and active transport. Vesicular transport is also discussed.
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- Function of cell membrane: - Barrier - Regulates entry and exit of substances - Sensitive to changes - Supports cell - Constant material exchange between fluids to maintain homeostasis - Fluid mosaic model → Model describing how cell membrane is composed of...
- Function of cell membrane: - Barrier - Regulates entry and exit of substances - Sensitive to changes - Supports cell - Constant material exchange between fluids to maintain homeostasis - Fluid mosaic model → Model describing how cell membrane is composed of many structures that flow and move around as needed forming a semi-permeable barrier - Fluid → Flowing and moving around as needed - Mosaic → Composed of many structures - Semi-permeable → Allows some things to pass through, not everything - Cell membrane - Double layer of lipids (fat) with phosphate group - Hydrophobic tail afraid of water and hydrophilic head loves water making phospholipid bilayer - Cholesterol embedded - Structure regulates semi-permeability - Membrane made of lipids, lipid soluble substances dissolve through - Cholesterol and proteins provide function, integrity, stability - Proteins include carrier proteins, channel proteins, receptor proteins, and cell identity markers - Cell transport - Simple diffusion → Spreading particles from high to low concentration, fat soluble and micromolecules pass through membrane, no energy required, passive process - Facilitated diffusion → Requires transport proteins, size specific with channel protein, chemical specific with carrier protein through receptor site, no energy required, passive process, with concentration gradient high to low concentration - Active transport → Requires energy, moves against concentration gradient, from low to high concentration - Vesicular transport → Active transport, requires energy, includes endocytosis and exocytosis, vesicle matches CM structure - Endocytosis→Cell eating where membrane folds forming vesicle, vesicle pinches off membrane, floats in cytoplasm - Exocytosis→Cell vomiting, vesicle fuses with membrane then pushes out to extracellular fluid
