Please enable JavaScript.
Coggle requires JavaScript to display documents.
B2.1 Membranes & Membrane Transport - Coggle Diagram
B2.1 Membranes & Membrane Transport
Membrane Structure & Composition
Membrane Components
Lipids
Phospholipids (amphipathic)
Glycolipids
Cholesterol
Proteins
Intergral
Transmembrane, amphipathic, hard to remove
Peripheral
Surface, hydrophilic, easy to remove
Carbohydrates
Glycolipids
Forms the
Glycoclayx
Cell recognition (
antigens
)
Cell adhesion (
CAMs
)
Cell signalling (signalling molecule interactions)
Protection (mechanical damage & pathogen entry)
Glycoproteins
Phospholipid Bilayer
Permeability
Amphipathic
Accepts
small, uncharged molecules
Rejects
large polar molecules & ions
Fluid Mosaic Model
Fluidity regulators
Saturated
fatty acids increases
rigidity
Unsaturated
fatty acids increases
fluidity
Cholesterol
stabilises the membrane
Reduces
tight packing
at
lower
temperatures
Reduces
fluidity
at
higher
temperatures
Importance of Fluidity
Proteins can move/conformationally change
Enables transportation processes
Enables for membrane repair
Allows cells to adapt to temperature changes
Functions
Barrier to hydrophilic/polar/charged molecules
Supports endocytosis & exocytosis
Membrane Proteins & Fucntions
Peripheral Proteins
Transport
Channels
Gated
Voltage
E.g. Sodium ion gates
Ligand
Mechanically
Special e.g. Aquaporins
E.g. Water uptake in root cells
Carriers
Conformational changes after binding
E.g. GLUT transporters in RBCs
Pumps
Uses ATP/against a gradient
E.g. Sodium/Potassium pump (
32
)
Co-transporters
One solute against gradient/one solute with gradient
E.g. Sodium-glucose co-transporter (intestinal absorption)
Receptors
Binds ligands to trigger intracellular responses
E.g. Nicotinic Acetylcholine receptors (neurons)
Enzymes
E.g. Sodium/Potassium ATPase
Integral Proteins
Recognition
Tags for immune/cell recognition
E.g. Blood group glycoproteins
Adhesion
Binds to other cells or ECMs
E.g. CAMs for cardiac/epithelial tissues
Structural
Maintains cells shape & cytoskeleton
Transport Mechanisms
Passive Transport
Simple diffusion (
down a gradient
)
Osmosis (
with water
)
Facilitated diffusion (
channel & carrier protein assisted
)
Active Transport
Direct (
ATP-driven
)
E.g. Sodium/Potassium Pump
Indirect (
co-transport
)
E.g. sodium-glucose co-transporter (in intestines)
Bulk Transport
Endocytosis
E.g. Phagocytosis
Exocytosis
Requires
fluidity
of the membrane
E.g. insulin secreted out of pancreatic cells
Cell Adhesion & Junctions
CAMs
Enables cell-cell & cell-ECM attachment
Located on
Cellular Junctions
Types of Cellular Junctions
Tight
To form barriers/prevent leakage between cells
Anchor
To provide mechanical integrity (e.g. for skin and cardiac tissue)
Gap
To form channels for direct communication between cells