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Chapter 7: Membrane Structure and Function - Coggle Diagram
Chapter 7: Membrane Structure and Function
Membrane Structure & Fluid Mosaic Model
Phospholipid bilayer amphipathic
Hydrophobic tails inside
Hydrophilic heads outside
Proteins embedded mosaic
Proteins form functional groups
Membrane Fluidity
Weak hydrophobic interactions allow lateral drift
Unsaturated fatty acids ↑ fluidity
Saturated fatty acids ↓ fluidity
Cholesterol
Warm temps restrains movement
Cool temps prevents packing
Adaptations in extreme temps
Fish poly-unsaturated tails
Winter wheat more unsaturated in cold
Membrane Proteins & Functions
Integral vs Peripheral
Transmembrane α-helix segments
Attachment cytoskeleton or ECM
Functions
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to cytoskeleton / ECM
HIV example CD4 + CCR5 receptor
Carbohydrates & Membrane Sidedness
Glycolipids and Glycoproteins
Short branched oligosaccharides
Cell-cell recognition markers
Asymmetrical distribution set in ER / Golgi
Selective Permeability
Hydrophobic molecules (O2 CO2) cross easily
Hydrophilic molecules slowed or blocked
Transport proteins give specificity
Channel proteins e.g. aquaporin
Carrier proteins change shape
Passive Transport
Diffusion down concentration gradient
Osmosis water moves to higher solute
Tonicity
Isotonic -> stable
Hypertonic -> cell shrivels
Hypotonic -> cell swells / lyses
Osmoregulation examples
Paramecium contractile vacuole
Extreme halophiles adaptations
Plant cells
Turgid (hypotonic) healthy
Flaccid (isotonic)
Plasmolysis (hypertonic)
Facilitated diffusion
Channels (gated)
Carriers
Active Transport & Electrochemical Gradients
Requires ATP
Carrier proteins only
Sodium-potassium pump (animals) 3 Na+ out / 2 K+ in
Proton pump (plants, fungi, bacteria)
Membrane potential voltage
Electrochemical gradient = chemical + electrical
Cotransport
H+ / sucrose symport in plants
Na+ / glucose symport in intestines
Bulk Transport
Exocytosis vesicle fuses releases contents
Insulin secretion example
Endocytosis
Phagocytosis “eating” -> food vacuole
Pinocytosis “drinking” nonspecific
Receptor-mediated endocytosis LDL uptake