Life’s Guardian … Cell Membranes …their Structure & Function

1. Life’s Guardian… Cell Membranes …their Structure & Function

2. How do things enter and leave living cells? How does carbon dioxide and other waste products leave our cells? Do cells drink and eat? How does oxygen get into our cells? How do nutrients enter our cells? How do white blood cells engulf foreign invaders?

3. All living cells are surrounded by an extracellular fluid(ECF).

4. Besides other organisms, there are many chemicals in the ECF. SMALL HYDROPHOBIC MOLECULES LARGER UNCHARGED POLAR MOLECULES O2 , CO2 , N2 , benzene amino acids, glucose, nucleotides H2O, alcohols IONS SMALL UNCHARGED POLAR MOLECULES N+ , Na+ , HCO 3- , K+, Ca2+ , Cl - , Mg 2+

5. Solutions where the water is the solvent such as the ECF and blood are called aqueous solutions. solvent Solution

6. A solution is a combination of a solvent with one or more solutes. solvent Solution solute If this solution was blood the solvent would be called plasma and the solute would be red and white blood cells.

7. An organism's chemical processes are carried out inside cells and/or it’s organelles. Biochemical reactions require raw materials from outside the cell and generate waste products inside that the cell must discharge back into its environment.

8. In order to do this and remain alive a cell must maintain CHEMICAL HOMEOSTASIS. Homeostasis is the maintenance of a steady state or balance within the cell or organism.

9. The PLASMA MEMBRANE plays a major role in the maintenance of homeostasis as it determines what enters and leaves the cell.

10. Life’s Hangout Plasma membrane Embedded Proteins Phospholipids

11. Gk: phil – loving phob – fear Life’s Hangout Phospholipids hydrophillic or water loving head hydrophobic or water fearing end ~75-95% of the cell’s plasma membrane

12. Life’s Hangout Embedded Proteins Carrier proteins that regulate transport and diffusion ~5-25% of the cell’s plasma membrane Marker proteins that identify the cell to other cells And receptor proteins that allow the cell to receive instructions

13. Life’s Hangout Embedded Proteins Embeddedproteins provide the cell witha pore for thepassive transportof solute particles. Diffusion concentration gradient

14. Life’s Hangout Embedded Proteins Carrier proteins provide the cell with a means of active transport. facilitated diffusion concentration gradient

15. Life’s Hangout Embedded Proteins Symport carrier proteins provide the cell with a means of two-way diffusion. Sodium-Na+ Active Transport Glucose concentration gradient ATP

16. Life’s Hangout Embedded Proteins Marker proteins extend across the plasma membrane and serve to identify the cell. The immune system uses these proteins to tell friendly cells from foreign invaders.

17. Life’s Hangout Embedded Proteins Receptor proteins are used in intercellular communication. In this animation a hormone binds to the receptor. This causes the receptor protein to release a chemicalsignal to perform a specific action.

19. Life’s Hangout Embedded Proteins A The passive transportof solvent molecules like water is called …. B concentration gradient

20. Life’s Hangout Review Cells are essentially a selectively permeable sack of particles dissolved in water with larger complex structures suspended in the resulting solution. For this reason, it is important to know what a solution is before attempting to understand how cells respond to changes in their environments.

21. Simple Diffusion