Aim: How does the structure of the cell membrane contribute to its function?
1. What is the function of the structure below? CELL MEMBRANE Forms the Boundary of cell. CONTROLS what enters (NUTRITION) and exits the cell (EXCRETION).
2. Cell membrane Structure Phospholipids Proteins Some carbohydrates
3. Organization of lipids The cell membrane is composed of a special type of lipid (fat) called a phospholipid. PHOSPHOLIPID BI-LAYER Hydrophilic Head Hydrophobic Tail - afraid of water and tries to avoid it.
4. Proteins STRUCTURAL PROTEIN CHANNEL Structural Proteins: Membrane Proteins: Structural Proteins: Transport Proteins: (Channels) Receptor Proteins Enzymes STRUCTURAL PROTEIN CHANNEL
Receptors RECEPTORS Receptors found on the cell surface aid in cell to cell communication. Messengers (hormones) from other cells bind to these receptors (based on shape) and transfer information.
5. Why is this model called the fluid mosaic model? = + “Fluid” because the molecules are always changing position with each other and mosaic because it is made of different kinds of molecules. http://home.earthlink.net/~shalpine/anim/Life/memb.htm http://home.earthlink.net/~shalpine/anim/Life/memb.htm
An umbrella is impermeable 6. What is permeable? An umbrella is impermeable The window screen is semi –permeable, allows some things through. It does not allow materials through
7. Do all things get through the cell membrane? NO!!!
8. SELECTIVELY PERMEABLE or semi-permeable The cell membrane is selectively permeable-it allows certain materials through the membrane and can change its permeability over time.
9. What will get through the cell membrane? Things the cell needs: O2, Water, Nutrients Things the cell wants to get rid of: Metabolic Wastes (urea, CO2)
10. What determines Selectivity / Why can some things move in or out of cell and not others? SIZE - Small molecules are more likely to get through the cell membrane compared to big molecules Concentration - molecules generally move from where there is more to where there are less of them.
11. How do larger molecules enter or leave the cell? Protein Channels located in the plasma membrane create larger openings for larger molecules like glucose to enter.
1. Which statement best describes the plasma membrane of a living plant cell? It selectively regulates the passage of substances into and out of the cell. It is composed of proteins and carbohydrates only. It has the same permeability to all substances found inside or outside the cell. It is a double protein layer with floating lipid molecules.
2. Which statement is correct concerning the structure labeled A? (1) It aids in the removal of metabolic wastes in both cell X and cell Y. (2) It is involved in cell communication in cell X, but not in cell Y. (3) It prevents the absorption of CO2 in cell X and O2 in cell Y. (4) It represents the cell wall in cell X and thecell membrane in cell Y
3. The diagram below represents a portion of a cell membrane 3. The diagram below represents a portion of a cell membrane. Which structure may function in the recognition of chemical signals? Information can be sent from (1) cell A to cell B because cell B is able to recognize signal 1 (2) cell A to cell B because cell A is able to recognize signal 2 (3) cell B to cell A because cell A is able to recognize signal 1 (4) cell B to cell A because cell B is able to recognize signal 2