5. • The cell boundary;
separates cellular
materials from
external environment
• Regulates which
materials can enter
and exit the cell
• Maintains
homeostasis in cell
6. Semipermeable membranes
• Membranes that allow certain materials to
pass through based on certain properties
– size
– hydrophobicity
– charge
7. The Fluid Mosaic Model: The membrane is
made up of many smaller parts and the
structure moves like a fluid
• http://www.susanahalpine.com/anim/Life/memb.htm
8. Phospholipids and proteins make up most of the
membrane. Cholesterol helps with flexibility, and
carbohydrate chains help communicate with other
cells
9. A phospholipid is a type of lipid that has
2 fatty acid tails and a phosphate head.
• http://telstar.ote.cmu.edu/Hughes/tuto
rial/cellmembranes/
The phosphate head is
hydrophilic
because it is attracted to
water
The fatty acid tails are
hydrophobic
Because they are repelled
by water
Use E-Life animation 6.3
https://www.youtube.com/watch?v=pzpZdijj
qX8
12. Clean up:
• Pour soap down drain
• Rinse plate, straw frame and beaker
VERY well
• Throw out used straws and thread ring
• Return plate, straw frame and beaker
• Wipe down table top VERY well
13. The phospholipid bilayer is a
semipermeable membrane because it
only allows certain molecules to cross.
14. Hydrophilic, polar, large and charged
molecules must use a Transport Protein to
enter/exit the cell.
The proteins are specific; glucose can only
pass through a glucose transport protein.
15. There are two types of Transport Proteins:
Protein Channels: a special entryway for
large, polar, hydrophilic and charged ions to
diffuse through the cell membrane
This is called Facilitated Diffusion.
Protein Pumps: we’ll talk about these later
16. The Big Idea
1. Name 4 components of the cell membrane
2. What kind of molecules CAN go through the
phospholipid bilayer?
3. What kinds of molecules CANNOT go through the
phospholipid bilayer?
4. What is facilitated diffusion?
5. Can any molecule go through any protein channel?
6. When will the molecules stop noticeably moving?
18. Passive Transport:
> Materials move down
the concentration gradient
from high to low solution
concentrations
> Equilibrium is reached
(concentrations are equal
all around)
> No energy (ATP) is
needed by the cell to
move the materials
19. Active Transport:
1. Materials move up the
concentration gradient,
from low to high solution
concentrations
2. Concentrations
become unbalanced on
either side of the
membrane
3. Energy (ATP) is
needed by the cell to
move the materials
23. Protein pumps are found cooperating with
protein channels in
photosynthesis and cell respiration
24. 2. Endocytosis: Materials enter the cell without
crossing the membrane—the membrane folds
around the particles and forms a new vacuole
inside the cell
25. Amoeba and white blood cells engulf large
food particles through phagocytosis (a type
of endocytosis).
http://www.youtube.com/watch?v=pvOz4V
699gk (mute: annoying soundtrack)
30. 1. What materials can diffuse through the
lipid bilayer without the aid of a protein?
2. What is the difference between facilitated
diffusion and the use of a protein pump?
3. What are the major differences between
Passive Transport and Active Transport?
4. Explain why an animal cell bursts when
placed in a hypotonic solution.