1. Section 3-3, 3-4, 3-5 “Movement across the cell membrane”
Write everything that is underlined

2. 3.3 KEY CONCEPT: The cell membrane is a barrier that separates a cell from the external environment.

3. Cell membranes are composed of two phospholipid layers.
It forms a boundary between inside and outside of the cell
…and controls passage of materials
cell membrane
outside cell
inside cell

4. The cell membrane is made of a phospholipid bilayer.
There are other molecules embedded in the membrane.
The fluid mosaic model describes the membrane.
cell membrane
protein
cholesterol
carbohydrate
chain
protein channel

5. How many layers is the cell membrane made up of?1 2 3 4

6. The cell membrane is selectively permeable (only certain things get through) like a screen door

7. 3.4 KEY CONCEPT: Materials move across membranes because of concentration differences.

8. Passive transport does not require energy
There are two types of passive transport:
diffusion
osmosis

9. Diffusion: Molecules move down a concentration gradient
“From an area of high concentration to low concentration”

10. Osmosis is the diffusion of water
There are three types of solutions: isotonic, hypertonic, hypotonic

11. What is passive transport?
Does not require energy to move materials
Requires energy to move materials
Depends on your definition of movement
Only sometimes does it use energy

12. What is/are the different types of passive transport?
Diffusion
Isotonic
Osmosis
A and C

13. Diffusion is the movement of materials from an area of ___________ concentration to ______ concentration
Low to High
High to High
Low to Low
High to Low

14. Osmosis it the diffusion of ___________
Materials
Sugar
Water
Amino acids

15. Facilitated diffusion: diffusion through transport proteins
Some molecules can only diffuse through transport proteins.
Facilitated diffusion: diffusion through transport proteins

16. 3.5 KEY CONCEPT: Cells use energy to transport materials that cannot diffuse across a membrane.

17. Active transport requires energy to move a substance against its concentration gradient (from LOW to HIGH)
Passive transport requires no energy from the cell
Active transport is powered by chemical energy (ATP)
Cells use active transport to maintain homeostasis

18. A cell can import and export large materials or large amounts of material in vesicles during the processes of endocytosis and exocytosis.
Endocytosis is the process of taking material into the cell – also called Phagocytosis

19. Exocytosis is the process of expelling (pushing out) material from the cell

20. What is the difference between active transport and passive transport?
Active requires energy and passive does not
Passive requires energy and active does not
Passive moves big materials into the cell and active does not
B and C

21. What does the following picture show?
Endocytosis
Exocytosis
Diffusion
Osmosis