1. “Cell Environment” Notes
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“Cell Environment” Notes

2. Selectively permeable
Some things can pass through the cell membrane & some can’t

3. Ways of moving through a cell membrane:
Passive transport – no energy needed
Active transport – needs energy

4. Diffusion
Passive
Molecules move from an area of higher concentration to an area of lower concentration

5. Why diffusion happens Molecules are always moving
They bump into each other
Causes them to spread out

6. Osmosis
Diffusion of water
Passive

7. Why can’t people drink large amounts of salt water??
Salt water causes water to move out of body cells

8. Active Transport
Move materials through cell membrane, using cellular energy
Two types:

9. 1. Transport Proteins “Pick up” outside molecules & bring them inside
Uses energy
Can move things in or out of cell

10. 2. Engulfing Cell membrane surrounds & engulfs a particle
Forms a vacuole with the particle inside
Uses energy

11. Why are cells small?
Materials must be able to flow through cytoplasm and reach their destination
Keep travel time low!
If cell grew too large, it could not function well enough to survive.