1. Membrane Protein : Integral/Peripheral
Integral Membrane Proteins (transmembrane)
Exposed to aqueous environment on both sides of the membrane
Used to transport molecules across membrane
Peripheral Membrane Proteins
Located on surface of a membrane
Eg. Cytoskeleton

2. Passive Membrane Transport
No chemical energy required
Diffusion
Net movement of a substance from a region of high concentration to a region of low concentration until dynamic equilibrium between cells is met

3. Simple Diffusion (Passive Transport)
Diffusion of small/non-polar molecules across plasma membrane without the help of an integral protein

4. Facilitated Diffusion
Diffusion of large/polar molecules with the help of a transport protein (integral membrane protein)
Stops when equilibrium is reached
Two types of Transport (Integral) Proteins
Channel proteins
Carrier proteins

5. Facilitated Diffusion
Channel Proteins
Form hydrophilic pathways in the membrane
Water and certain ions can pass
Voltage-gated channels
Open or closed by changes in voltage across the membrane or by binding molecules
Eg. Muscle contractions

6. Facilitated Diffusion
Carrier Proteins
Form pathways through the membrane
Bind to a specific solute (glucose, amino acid)
Carrier protein changes shape allowing solute to move from one side of the membrane to the other

7. Simple vs Facilitated Simple Diffusion Facilitated Diffusion
Rate of diffusion increases as difference in concentration gradient increases
Facilitated Diffusion
Maximum rate is reached but limited by number of transport protein in membrane

8. Osmosis Passive diffusion of water across a membrane via aquaporins
Water always diffuses from an area of low solute concentration (high water concentration) to an area of greater solute concentration (low water concentration)
Three Solutions
Remember our cells are isotonic
Hypotonic
Solute concentration is high in cell compared to environment
Cell will swell
Hypertonic
Solute concentration is low in cell compared to environment
Cell will shrink
Isotonic
Solute and water concentration is equal both in and outside cell

9. Active Membrane Transport
Substance carried across a membrane from an area of low concentration to an area of high concentration
Use of pump
ATP used as energy source
Two Types
Primary Active Transport
Secondary Active Transport

10. ATP Adenosine triphosphate Nucleotide
Supplies energy that powers nearly every cellular function
Energy “currency”
Other forms of energy
GTP, UTP

11. Where Does Energy From ATP Come From?
Consists of
Nitrogenous base (adenine)
5 carbon sugar (ribose)
3 phosphate groups
Free energy comes from the three negatively charged phosphate groups

12. Hydrolysis of ATP Phosphorylation
Addition of a phosphate (PO₄³⁻) group to a protein or other organic molecule
Used in a wide range of cellular processes
Activate or de-activate specific proteins

13. Primary Active Transport
Pumps that moves positively charged ions across membranes (H⁺. Ca²⁺, Na⁺, K⁺)
ATP is hydrolyzed
Phosphate group attaches to pump allowing ion to bind to protein transporter
Protein transporter undergoes a folding change exposing ion to opposite side of membrane
Ion is released to side of higher concentration
Phosphate group is released
Electrochemical gradient created
Difference in ion concentration across membrane
Stored potential energy
ATP synthesis
Nerve signalling

14. Secondary Active Tranport
Uses concentration gradient of an ion as its energy source
This gradient was already established by primary pump
Transport solute across membrane
Two ways
Symport
Solute moves through channel in the same direction as ion
Antiport
Solute moves in opposite direction as ion

15. Exocytosis Vesicles are used to transport ATP is required
Transport of soluble proteins, membrane proteins and lipids
Degranulation
Cells release antimocrobial cytotoxic molecules
Immune response
Histamine (allergic reaction)

16. Endocytosis Transport of molecules inside cell Pinocytosis
Large polar molecules
Pinocytosis
ECF and molecules
Phagocytosis
Immune response
Macrophage
Receptor-mediated
Clathrin (protein) assists in ingestion of specific molecules inside cell