Biology Exam 2 study guide

Biology Exam 2 study guide - Key Concepts Topic 6: 1. How...

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Key Concepts Topic 6: 1. How do lipids differ from the other 3 classes of macromolecules? They are non-polar (the others are polar) and they do not form polymers (only can form macromolecular structures). 2. What does "saturated" mean, in the context of fatty acids? What is the effect on the shape of the fatty acid if it is not saturated? Which are liquid or solid, and why? Saturated means that the bonds in the C-C tail are all single bonds (with one pair of shared electrons), these fatty acids can pack tightly causing them to be solids at room temperature. If the tail is unsaturated the double bonds cause kinks in the fatty acid tails so they cannot pack as tightly as the saturated fatty acids, causing them to be liquid at room temperature. 3. Which kinds of fats can be problems in human diets: saturated, unsaturated, polyunsaturated, or partially hydrogenated? Saturated and partially hydrogenated. Saturated can be problems because modern humans have a comparatively inactive lifestyle so they have a hard time metabolizing the saturated fats. They can contribute to coronary artery disease (clogged arteries) and heart attacks. Partially Hydrogenated fats are as bad, maybe worse for humans than animal fats. They are made in a lab with the purpose of increasing shelf life of foods. Unsaturated are healthier than saturated (can be found in plant foods ex. Nuts, seeds, vegetables) Polyunsaturated fats-multiple double bonds, healthy for humans 4. What is special about phospholipids and how are they able to form barriers in cells?
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Phospholipids are special because they are both hydrophilic and hydrophobic. They are able to form barriers in cells because of the hydrophobic effects of the tails. When in water the tails are driven to the middle of what spontaneously forms as a bilayer sheet held together by hydrophobic effect??? , the hydrophilic heads face into the aqueous solution on either sides of the bilayer. 5. What are the three classes of macromolecules that make up membranes? Lipids, Proteins, and Carbohydrates 6. Explain the "fluid mosaic model." Describes a mosaic in that the membrane is made up of many different types of molecules that are constantly moving (fluid). It describes that the lipids are NOT covalently bonded to one another, thus the proteins in the membrane can float freely. 7. How do cells regulate the fluidity of membranes? What membrane elements would be beneficial to an organism living in a very cold environment? In a very hot one? Cells regulate the fluidity of membranes by increasing the amount of cholesterol and saturated fats that make up the membrane. Cold temperatures make membranes less fluid so they solidify, unsaturated fatty acid tails would be helpful. In a hot environment it is helpful to add cholesterol to decrease permeability. 8. How does membrane function to keep important transmembrane proteins
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This note was uploaded on 09/23/2010 for the course MIC 181 taught by Professor Jorstad during the Spring '08 term at University of Arizona- Tucson.

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Biology Exam 2 study guide - Key Concepts Topic 6: 1. How...

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