1. Standard V-1, Part 2- Cell Processes
Science AHSGE
Standard V-1, Part 2- Cell Processes

2. Homeostasis
The ability of an organism or cell to maintain internal balance and stability by adjusting its physiological processes.
If normal state is not restored, death might occur.
Processes involved in homeostasis:
Nutrition- Use of nutrients
Digestion- Break down of materials into usable substances
Absorption- Ability of an organism/cell to take in materials from the outside environment
Transport- Movement of substances within an organism/cell
Biosynthesis- Making new compounds for growth, repair, or reproduction

3. Homeostasis Homeostasis processes cont’d:
Secretion- Release of substances within an organism/cell
Respiration- Release of energy from the breakdown of chemical compounds in the mitochondria
Photosynthesis- Autotrophic production of glucose from CO2 and H2O
Excretion- Rid of waste products to the outside of the organism/cell
Response- Reaction due to a stimulus
Reproduction (Fission)- Production of new cells by one cell dividing (mitosis and meiosis)

4. Passive Transport
Passive Transport- The diffusion of a substance across a biological membrane.
Diffusion- The net movement of particles from an area where there are many particles of the substance to an area where there are fewer particles of the substance.
High concentration to lower concentration
Requires no energy
Will continue until all concentrations are the same
Dynamic equilibrium- Particles will continue to move without an overall change in concentration.

5. Diffusion

6. Diffusion 3 factors affect rate of diffusion:
Concentration (amount of a substance)
Temperature (average kinetic energy of the particles)
Pressure (Force of particles against the area of membrane)
In each case, the higher, the faster
More collisions occur causing diffusion to occur faster

7. Facilitated Diffusion
Facilitated diffusion- Uses transport proteins to move other ions and small molecules across the plasma membrane
Passive transport because it does not require energy
Water can diffuse across the membrane, but most other substances can not
Can use water-filled transport (channel) proteins or
Carrier proteins (change shape as material passes through)

8. Osmosis
Osmosis- Diffusion of water across a selectively permeable membrane
In a solution, a solute is dissolved into a solvent.
Water is the solvent in a cell and its environment

9. Osmosis
Hypotonic Solution- Solution has a lower concentration of solute and higher concentration of solvent.
Cell will be cell will be hypertonic
Net movement of water will be into the cell, causing the cell to swell
In pure solvents, cells will burst
Ex: Distilled water, pure vinegar
Hypertonic solution- Solution has a higher concentration of solute and a lower concentration of solvent.
Cell will be hypotonic
Net movement of water will be out of the cell, causing the cell to shrink

10. Osmosis
Isotonic Solution- The solution has the same concentrations of solutes and solvents as the cell.
Cell is also isotonic
Water will enter and leave the cell at equal rates, allowing for the cell to remain unchanged.

11. Osmosis Practice

12. Active Transport
Active transport- Movement of substances across the membrane from an area of lower concentration to an area of higher concentration; against the concentration gradient.
Requires energy
Uses carrier proteins called pumps
Maintains the proper balance of substances it needs to maintain homeostasis

13. Active Transport Sodium-potassium ATPase Pump
Found in cell membrane of animal cells
Uses energy to transport 3 sodium ions out, while moving two potassium ions in (decreases sodium concentration inside the cell)
Coupled transport- Sugar molecules attach to sodium ions to be transported into the cell without energy through the coupled channel

14. Active Transport
Endocytosis- Cell surrounds a substance in the outside environment, enclosing it in a portion of the membrane.
Pinches off into a vacuole
Pinocytosis- Cell drinking
Phagocytosis- Cell eating
Exocytosis- Vesicles surround waste inside the cell, attach to the cell membrane, and expel materials to the outside environment.