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Chapter 7 Membrane Structure & Function - Coggle Diagram
Chapter 7 Membrane Structure & Function
Plasma Membrane Structure
Fluid Mosaic Model
describes the membrane as a fluid structure with proteins embedded in a phospholipid bilayer
Plasma Membrane
Boundary that separates the cell from its environment
Key Components
Phospholipid Bilayer
Hydrophilic heads face outward
Hydrophobic tails face inward
forms the basic membrane structure
Cholesterol
stabilizes membrane
maintains fluidity
Membrane Proteins
embedded within the bilayer
perform transport and signaling
Carbohydrates
attach to proteins or lipids
important for cell recognition
Membrane Proteins
Integral Proteins
embedded in membrane
often span entire bilayer
Peripheral Proteins
attached to membrane surface
Functions of membrane proteins
transport
enzymatic activity
signal transduction
cell recognition
intercellular joining
attachment to cytoskeleton
Membrane Selective Permeability
selectivity Permeable
membrane allows some substances to pass while blocking others
Substances that cross easily
small nonpolar molecules
Oxygen
Carbon Dioxide
Harder to cross
Ions
large molecules
polar molecules
Passive Transport
Diffusion
movement from high concentration - low concentration
Example : Oxygen entering cells
Facilitated diffusion
diffusion using transport proteins
Example : glucose entering cells
Osmosis
diffusion of water across a membrane
often occurs through aquaporins
Osmotic Conditons
Isotonic Solution
Equal solute concentration inside and outside the cell
Result: no net water movement
Hypertonic Solution
Higher solute concentration outside the cell
Result: water leaves cell, cell shrinks
Hypotonic Solution
Lower solute concentration outside the cell
Result: water enters cell, cell swells
Plant Cells
Turgid = healthy
Plasmolysis = membrane pulls from wall
Active Transport
requires ATP
moves substances against the concentration gradient
Sodium - Potassium Pump
Pumps
3 Na Out
2 K in
Important for
nerve cells
muscle cells
Electrochemical Gradient
combination of
concentration gradient
electrical charge difference
Bulk Transport
Used for large molecules or particles
Endocrytosis
cell takes material into the cell
types
phagocytosis - cell eating
pinocytosis - cell drinking
receptor mediated endocytosis - uses receptors
Exocytosis
vesicles release molecules outside the cell
example
hormone secretion
neurotransmitter release
