1. Cell Membrane Structure and Cell Transport
How do materials get across the cell membrane

2. Structure of the Cell Membrane
Cell membrane is a fluid structure
(not rigid)
Selectively permeable
Only lets certain substances in and out of the cell

3. Structure of the Cell Membrane

4. Structure of the Cell Membrane
Remember lipids are nonpolar
Cell membrane has a polar head (water loving) and a nonpolar tail (water fearing).
PHOSPHOLIPID BILAYER – Allow lipids and other
substances that dissolve in lipids to
pass through, BUT water can also go through
the cell membrane (even though it is polar)
because it is so small.

5. Structure of the Cell Membrane
Proteins embedded in the cell membrane.
Remember: proteins are made of long chains of amino acids – some of those amino acids are polar and some are nonpolar
Attraction between the polar amino acids and the polar heads and the nonpolar amino acids and the nonpolar tails keeps the proteins embedded

6. Structure of the Cell Membrane
Transporter Proteins
Receptor Proteins
Two types:
Channel proteins and carrier proteins
Let things that are large and polar into and out of the cell
Receive environmental signals (such as hormones) and bring them into the cell

7. Cell Transport Passive Transport Active Transport
No energy is required
Two types:
Diffusion
Simple
Facilitated
Osmosis
Energy is required (ATP)
Two types:
Protein pumps – (specific type of transport protein)
Bulk transport
Endocytosis
Exocytosis

8. Passive Transport – Simple Diffusion
Substances move from an area of “high” concentration to an area of “low concentration”
Move down the concentration gradient
Diffusion occurs until equilibrium has been reached – equal concentration on both sides of a cell membrane

9. Passive Transport – Facilitated Diffusion
Still passive transport
Still moving from an area of high concentration to an area of low concentration until equilibrium is reached
Difference – a transport protein is needed for the substance to get
across the cell membrane

10. Passive Transport – Simple Diffusion vs. Facilitated Diffusion

11. Passive Transport – Osmosis (diffusion of water)
Isotonic – balance of water (equal)
Hypotonic – water moves in
Hypertonic – water moves out

12. Osmosis (diffusion of water) - hyponatremia
Jennifer Strange’s Stomach

13. Osmosis (diffusion of water) - hyponatremia
Brittney Chambers of Colorado (2001), Leah Betts of Great Britain (1995), and Anna Wood of Australia (1995) died after reportedly taking Ecstasy and drinking large amounts of water.
Fraternity hazing killed Matthew Carrington, a student at California State Chico February 2005.
In Sacramento, Jennifer Strange died after a water-drinking contest "Hold your wee for a Wii” sponsored by a local radio station, January 2007.
A 28-year-old female Boston marathoner died in 2002.
Artist Andy Warhol died after hospital staff accidentally administered excess water after gall bladder surgery (1987).
Infants fed diluted formula for extended periods of time can suffer from hyponatremia.

14. Active Transport - ATP Energy unit
Nucleic acid (macromolecule – DNA, RNA and ATP)
Made of nucleotides
Nitrogen base
Sugar
Phosphate group

15. Active Transport - ATP Energy is stored in these bonds
When these bonds break, an enormous amount of energy is released

16. Active Transport – Using a protein pump
Requires use of protein pump (transport protein) in cell membrane
Substances moves from an area of low concentration to an area of high concentration
Moves AGAINST the concentration gradient

17. Active Transport – Bulk Transport
Movement of large macromolecules (proteins/complex carbs) across cell membrane
Endocytosis
Exocytosis
Cell membrane engulfs a substance and pinches off to form a vesicle
Brings substances INTO a cell
Vesicle fuses with cell membrane
Brings substances OUT (EXTERIOR) of a cell