<p>Section G: Cell processes and applications (Transport across cell membrane)</p><p>G1.) Apply knowledge of organic molecules to explain the structure and function of the fluid-mosaic membrane model.</p><p>Fluid mosaic model of cell membrane: - the membrane is fluid-like - it has proteins throughout it - pores/channels - enzymes - cell markers - it also has cholesterol throughout it - cell membrane is mostly comprised of phospholipids - gives fluidity to cell membrane.</p><p>G2.) Explain why the cell membrane is described as “selectively permeable”</p><p>Selectively permeable: cell membrane can choose (select) what goes in or out of cells.  example of selection 1.) Non-polar = lipid can “slip” through the cell membrane as the cell membrane is made of lipids. 2.) Polar = glucose being polar needs to go through a protein channel. 3.) By size = very small particles can easily go through a protein channel. Membrane  oxygen and carbon dioxide Large molecules are kept out  bacteria and starch.</p><p>** Protein channels are specific for certain substance. ** 4.) By charge = small charged ions need to go through a channel.  Na+, Cl-</p><p>Side-note: How does water get across membrane?  Because water is polar, it needs to go through a protein channel, and because of the high amount of the protein channels for water, it can easily go back and forth across the membrane.</p><p>G3.) Compare and contrast the following: diffusion, facilitated transport, osmosis, and active transport.</p><p>4 ways to transport across the cell membrane: a.) Diffusion b.) Osmosis c.) Facilitated transport d.) Active transport</p><p>Diffusion: movement of a substance from an area of high concentration to an area of low concentration.  Carbon dioxide and oxygen can travel across cell membrane by diffusion.</p><p>Osmosis: (refers to the diffusion of water) the movement of water from an area of high concentration of water to an area of low concentration of water.</p><p>Facilitated transport: diffusion using a carrier protein in the cell membrane.  glucose ** you will need a protein carrier and it is with concentration gradient.</p><p>Concentration gradient: from high concentration to low concentration</p><p>Active transport: transport of molecules against the concentration gradient  movement of a substance from an area of low concentration to an area of high concentration using a protein channel and ENERGY!!  You need protein carrier, energy and against [ ] gradient for active transport.</p><p>G4.) Explain factors that affect the rate of diffusion across a cell membrane.</p><p>Rate of diffusion: 1.) temperature speeds up rate 2.) [ ] speeds up rate 3.) Size of molecule 4.) Viscosity of the medium  “thickness” of the solution</p><p>G5.) Describe endocytosis, including phagocytosis and pinocytosis, and contrast it with exocytosis.</p><p>Endocytosis v.s. Exocytosis - Other ways material can get in and out of cell</p><p>Endocytosis: cell eating or drinking 1.) The cell invaginates making a hollow/cove 2.) The molecules to be taken in fill the cove 3.) The cell membrane pinches off a vesicle. 4.) The vesicle can then fuse with a lysosome to be digested.</p><p>2 types: Phagocytosis Pinocytosis Cell eating Cell drinking Large molecules Small molecules.</p><p>Exocytosis: (“exo” means to leave or exit) opposite of endocytosis  golgi bodies making and releasing insulin. G6.) Predict the effects of hypertonic, isotonic, and hypotonic environments on animal cells.</p><p>[ ] of solutes are equal, so it is isotonic 20% salt solution 20% </p><p>Hypertonic = ↑ solute [ ] The solution is hypertonic to the cell. 20% salt solution 10% Hypotonic = ↓ solue [ ] Water The cell is hypotonic to the solution.</p><p> Water will move via osmosis to the salt solution from the cell. This is called crenation shrivel, plasmolysis, shrink, wilt).</p><p>- The solution is hypotonic to cell. - The cell is hypertonic to the solution</p><p>10% salt solution 20%</p><p>Water</p><p> Water will move into the cell causing cell to swell (burst, lyse) or become turgid.</p><p>Osmotic pressure: the pressure of water rushing out “leaving.”</p><p>G7.) Demonstrate an understanding of the relationship and significance of surface area to volume, with reference to cell size. Less efficient More efficient -Energy may not - require less nutrient get to the nucleus - greater SA:V ratio, more nutrient availability.</p>