biol1201 good study guide test 2

biol1201 good study guide test 2 - BIOL1201 Exam 2 Study...

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BIOL1201 Exam 2 Study Guide 1/51 Biol 1201 Section 1 Examination Two Thursday, March 6 at 6:00 PM in Campbell Auditorium Bring your LSUID and a number two pencil. I'll provide the questions and a scantron. 52 questions = 104 points Know the material well! Read the exam questions and answers carefully. KNOW END PRODUCTS One study suggestion - If you have a study partner, try to explain the summary figures from the chapters and the figures listed in this study guide to one another. Often if you stare at a figure long enough you think you have it down. However, if you try to explain it to someone, it becomes clear whether you really do understand it. Membranes and membrane function 8 Questions 1. How are membranes adjusted for different temperatures? a. A membrane remains fluid as temperature decreases, until finally the phospholipids settle into a closely packaged arrangement and the membrane solidifies, much as bacon grease forms lard when it cools. b. The temperature at which a membrane solidifies depends on the types of lipids it is made of. c. The membrane remains fluid to a lower temperature if it is rich in phospholipids with unsaturated hydrocarbon tails i. Because of kinks in the tails where double bonds are located, unsaturated hydrocarbons cannot pack together as closely as saturated hydrocarbons, and this makes the membrane more fluid. d. At relatively warm temperatures (37 degrees Celsius – the body temperature of humans, for ex) cholesterol makes the membrane less fluid by restraining the movement of phospholipids i. Because cholesterol hinders the close packaging of phospholipids, it lowers the temperature required for the membrane to solidify 1. Cholesterol can be thought of as a “temperature buffer” for the membrane, resisting changes in membrane fluidity that can be caused by changes in temperature. e. The lipid composition of cell membranes can change as an adjustment to changing temperature. 2. Transport of materials across the membrane a. Diffusion : The tendency for molecules of any substance to spread out evenly into the available space. i. In the absence of other forces, a substance will diffuse from where it is more concentrated to where it is less concentrated. ii. Concentration gradient : An increase or decrease in the density of a chemical substance in an area. It represents potential energy and drives diffusions. Cells often maintain concentration gradients of ions across their membranes.
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BIOL1201 Exam 2 Study Guide 2/51 1. No work must be done to make this happen; it is spontaneous. b. Passive Transport : The diffusion of a substance across a biological membrane. (The cell does not require energy to make it happen.) i. Facilitated Diffusion – Spontaneous passage of polar molecules and ions impeded by the lipid bilayer of the membrane (bound to specific carrier/transport proteins) across a biological membrane down their concentration gradients. 1.
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biol1201 good study guide test 2 - BIOL1201 Exam 2 Study...

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