1. Cell Transport
Movement of molecules across cell membranes

2. Types of Transport 1) Passive Transport
No _____ (work) expended by cell
Molecules move ____ a concentration gradient
Caused by Random Molecular Motion
(_________ Motion)
____ energy moves molecules
Motion stops at “absolute zero” (-2730C/-4600F)
Cell transport > passive transport

3. E.g., diffusion of ink molecules in water
Is a type of __________
E.g., diffusion of ink molecules in water
Water is the ______: fluid something is dissolved in
Ink is the ______: the substance that is dissolved
Cell transport > passive transport

4. Ink molecules move to areas of lower concentration
Move until they reach ___________
Equal ___________ throughout
What “moves” the molecules?
Heat energy: causes molecules to collide
Cell transport > passive transport

5. Osmosis: Diffusion of water across a ________________
Biological membranes are ______________
______ can pass
Solute (e.g., salt) can not pass
Cell transport > passive transport > osmosis

6. Glass tube model of osmosis
Semi-permeable
membrane
Cell transport > passive transport > osmosis

7. Solute molecules
Cell transport > passive transport > osmosis

8. at higher concentration
Same solute molecules,
at higher concentration
Cell transport > passive transport > osmosis

9. This is unstable, not at equilibrium What will happen? water Hypotonic
solution
Hypertonic
solution
This is unstable,
not at equilibrium
What will happen?
Hint: molecules travel
down their concentration
gradient
water
Cell transport > passive transport > osmosis

10. Solute molecules can’t pass, So _____ (solvent) does
Solution becomes ________
Equal concentration throughout
Creates _______ Pressure on right side
A type of ______ energy
Can be put to use, as plants do
Cell transport > passive transport > osmosis

11. Water gets ‘____’ through membrane by _____
Explanation:
Water gets ‘____’ through membrane by _____
Cell transport > passive transport > osmosis

12. Examples of osmosis a) Freshwater microbe placed in salt water
Environment hypertonic or hypotonic ?
_________
Direction of water movement ?
__________
Salt _____ move inward
Result?
___________
Cell transport > passive transport > osmosis

13. b) Freshwater microbe in purified water
Environment hypertonic or hypopotic ?
_________
Direction of water flow ?
________
Result ?
Cell _______,
“explodes”: lysis
Cell transport > passive transport > osmosis

14. 2) Facilitated passive transport
For molecules that can’t diffuse through membrane
Too ___
__________ charged
Uses _______ Proteins within cell membrane
Provide passageways for specific molecules
Cell transport > passive transport > facilitated

15. Potassium ion channel:
Examples:
Transport
protein
Channel
Potassium ion channel:
Necessary for nerve impulses
Aquaporin protein
Allows rapid passage of _____ through cell membrane
2003 Nobel Prize in Chemistry
Cell transport > passive transport > facilitated

16. Active Transport Moves molecules ___ their concentration gradient
Requires cell to spend energy, to work
Mechanism is called an ___ pump
Energy used is
ATP molecule
(more on ATP later)
E.g., moves _____________ across cell membranes
in cellular respiration and photosynthesis
Cell transport > active

17. Endocytosis Used to ________ large molecules and particles
Plasma membrane morphs into a ___________
Requires energy
“cellular eating”
Cell transport > endocytosis