1. Membrane Structure & Molecule Transport Part 2
AP Biology
Membrane Structure
& Molecule Transport
Part 2

2. Cell Membrane

3. Tunnel Transport proteins
EXTRACELLULAR
FLUID
Channel protein
Solute
CYTOPLASM

4. “Grabber” Transport proteins
Carrier protein
Solute

5. Diffusion

6. Osmosis

7. . Hypotonic solution Isotonic solution Hypertonic solution Animal cell
H2O
H2O
H2O
H2O
Lysed
Normal
Shriveled
Plant
cell
H2O
H2O
H2O
H2O
Turgid (normal)
Flaccid
Plasmolyzed

8. Positive Pressure Potential

9. Negative Pressure Potential

10. Solute Potential
ΨS = -iCRT -i (ionization constant) C (molar concentration) R (pressure constant) T (temperature in Kelvin)

11. Total Water Potential problems

12. Facilitated Diffusion
EXTRACELLULAR
FLUID
Channel protein
Solute
CYTOPLASM

13. Active Transport Cytoplasmic Na+ bonds to the sodium-potassium pump
EXTRACELLULAR
FLUID
[Na+] high
[K+] low
Na+
Na+
Na+
Na+
Na+
Na+
Na+
Na+
[Na+] low
[K+] high
ATP P
Na+ P
CYTOPLASM
ADP
Cytoplasmic Na+ bonds to
the sodium-potassium pump
Na+ binding stimulates
phosphorylation by ATP.
Phosphorylation causes
the protein to change its
conformation, expelling Na+
to the outside. K+ K+ K+ K+ K+ P P K+
Extracellular K+ binds
to the protein, triggering
release of the phosphate
group.
Loss of the phosphate
restores the protein’s
original conformation.
K+ is released and Na+
sites are receptive again;
the cycle repeats.

14. Cell Voltage Gradient

15. Proton pumps

16. Proton pumps and co-transport

17. Phagocytosis & Pinocytosis

18. RECEPTOR-MEDIATED ENDOCYTOSIS.
RECEPTOR-MEDIATED ENDOCYTOSIS
Coat protein
Receptor
Coated
vesicle
Coated
pit
Ligand
A coated pit
and a coated
vesicle formed
during
receptor-
mediated
endocytosis
(TEMs).
Coat
protein
Plasma
membrane
0.25 µm