1. Cell Membrane (Plasma Membrane)
TEAM BIO

2. Cell Membrane -“The Regulator”
Regulates HOMEOSTASIS by:
Controlling what enters and leaves cell
WALL between inside and outside of cell It
can bend

3. Questions: How does the Cell Membrane maintain HOMEOSTASIS?
Where is the cell membrane located on a cell?

4. Fluid Mosaic Model Describes structure membrane
Fluid: moves back and forth

5. Question:
Does the cell membrane move or is it rigid?

6. Cell membrane: like a plastic bag that holds everything inside

7. Cell Membrane on a Plant Cell

8. Cell (plasma) membrane
Stuff comes in….Stuff comes out…. IN
food
- sugars
- proteins
- fats
- salts
- O2
- H2O
OUT
waste
- ammonia
- salts
- CO2
- H2O
products
- proteins
cell brings materials in & products or waste out

9. Questions: What types of molecules (things) move into the cell?
What types of molecules (things) move out of the cell?

10. Made up of: 2 Layers with proteins in between:
Lipid Bi-Layer – “2” layers of lipids (fats)
with
Receptor Proteins in between
Transport molecules/out of cell
Like a Butler

11. Bi-Lipid Layer Heads: Tails: Tails: Heads: Like Water Don’t Like Water
inside cell
outside cell
Heads:
Like Water
Tails:
Don’t Like Water
Tails:
Don’t Like Water
Heads:
Like Water

12. Watch it wiggle…See it jiggle…
Receptor Protein

13. PROTEIN/RECEPTOR MOLECULE
“Hello – May I help you? Oh you’d like to enter? Sure, Come on in!”
inside cell
H2O aa
sugar
salt
outside cell
waste

14. Question: What is the cell membrane made up of?
Which of these parts helps molecules enter the cell?

15. ***Selective Permeability*** (Semipermeable)
Plasma Membrane is “PICKY”
Some things can enter/Some things cannot enter
Purpose of PERMEABILITY:
Maintain/regulate: HOMEOSTASIS

16. Semi-permeable membrane
So what needs to get across the membrane?
sugar
lipids aa O2
H2O
salt
waste

17. How do things enter? 1st : Signal 2nd: Receptor Protein gets signal
Like a doorbell ringing
2nd: Receptor Protein gets signal
Determines if molecule needs to enter/exit
Like Guard answering door and taking message

18. 3rd: Receptor protein (the guard) changes shape to match fit of th entering molecule
4th: Receptor Protein binds (attaches) to molecule (the guest)
5th: The pair (receptor protein and molecule) move inside to correct organelle

19. Similar to a LOCK and a KEY
Entering Molecule
LOCK
Receptor Protein

20. Shapes of Receptors
What shape will Receptors have to become if the molecule is shaped like a

21. The shapes fit together

23. Will the orange molecule get in? Why/Why Not?
Shape of RECEPTOR -
SIZE of molecule
Is it GOOD for cell?

24. Will the RED MOLECULE enter?

25. Let‘s try together:
On the next screen lets put these in the correct order:
# the steps on your paper in the correct order too!

26. Receptor Proteins identifies molecule
Receptor Protein binds to molecule and “escorts” the molecule inside the cell
Receptor Protein changes shape to match shape of visiting molecule
The pair (protein and message) go to the correct organelle in the cell
Chemical secreted – “alerts/SIGNALS”cell that a molecule wants in

27. Cell Membrane Used for excretion , excretory system
Similar to lungs – gets rid of waste gases that are not needed

28. The diagram below represents a portion of a cell membrane.
Which structure may function in the recognition of chemical signals?
(1) A (3) C
(2) B (4) D
The diagram below represents two molecules that can interact with each other
In order for entry into the cell.
Molecules A and B most likely represent
(1) a protein and a chromosome
(2) a receptor protein and a hormone molecule
(3) a carbohydrate and an amino acid
(4) an antibody and a hormone

29. Vocab Log Add: receptor protein- protein in cell membrane that recieves signal from incoming molecule selective permeability- cell membrane allows some things in and not others