1. How do cells FUNCTION (work)?
Cell Physiology
How do cells FUNCTION (work)?
STERNGRR Processes take place at the cellular level!
Cell Transport
Photosynthesis
Cell Respiration

2. Cell Transport is a STERNGRR process
• Lets food in for NUTRITION
• Lets oxygen in for RESPIRATION
• Lets waste out for EXCRETION
Materials move in/out of cells through the cell membrane
The cell membrane is SELECTIVELY PERMEABLE
Phospholipid bilayer
Membrane protein

3. Diffusion Demo
BEFORE:
Dialysis bag is “selectively permeable”
Starch (large molecule) inside bag
Iodine (small molecule) in beaker
AFTER:
Starch (large molecule) still inside bag; did NOT diffuse out
Iodine (small molecule) diffused INTO bag – evidence is color change

4. Types of Cell Transport Passive Cell Transport
Active cell transport
Does NOT require energy
Requires energy
Movement DOWN the
concentration gradient
Movement AGAINST the
High  Low
Low  High

5. Molecules move until they reach EQUILIBRIUM:
Diffusion
Diffusion is a type of Passive Transport
• Lets food in for NUTRITION
• Lets oxygen in for RESPIRATION
• Lets waste out for EXCRETION
Movement of molecules from a high to low concentration
Example:
Oxygen is moved from a high concentration in the lungs, to a low concentration in the blood
Molecules move until they reach EQUILIBRIUM:
An equal concentration on both sides of the membrane

6. Molecules move until they reach EQUILIBRIUM:
Osmosis
Osmosis is a type of diffusion
(a type of passive transport)
Movement of WATER molecules from a high to low concentration
Example:
In salt water, there is more WATER in the cell than in the surrounding environment, so water leaves the cells and they shrivel
Molecules move until they reach EQUILIBRIUM:
An equal concentration on both sides of the membrane