MEMBRANE TRANSPORT MECHANISM
MEMBRANE TRANSPORT MECHANISM
OBJECTIVES
• Understand factors that influence membrane permeability
• Know types of membrane transport and proposed mechanisms
MEMBRANE PERMEABILITY
Cell Membranes Are Selectively Permeable:
– Membranes allow flow of crucial materials in & out of cell while keeping out the unnecessary
TRANSPORT MECHANISMS
Permeability Depends on
Characteristics of Solute:
MEMBRANE PERMEABILITY: TRANSPORTED SUBSTANCE
TRANSPORT MECHANISMS• Active Transport
• Passive Transport
NOTE: Movement of substance can be into or out of cell!!!
PASSIVE TRANSPORT
MECHANISMSPassive Transport:
• Simple Diffusion
PASSIVE TRANSPORT
MECHANISMSPassive Transport
• Osmosis:
OSMOREGULATION• Cell survival depends on
balancing water uptake and loss
TONICITYTonicity• Compares solute
concentrations of two solutions – Hypertonic solution
– Hypotonic solution
– Isotonic solution
TONICITY
NOTE: Solute particles cannot move across membrane!!!
PASSIVE MECHANISMS
Passive Transport:
• Facilitated Diffusion:
ACTIVE TRANSPORT
MECHANISMSActive Transport
TRANSPORT OF LARGE MOLECULESBulk Transport Mechanisms:
• Endocytosis
TRANSPORT OF LARGE MOLECULESBulk Transport Mechanisms:
• Exocytosis