MCAT Biology Practice Exam Questions Graded A+ (Answered)

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The chemical reaction that breaks down all the major macro-molecules - ANSWER Hydrolysis What is the strongest type of INTER-molecular bonds? - ANSWER Hydrogen bonds are the strongest intermolecula... r bonds.... diople-dipole bonds are weaker. . . Vander wall bonds are the weakest. Why is water a liquid at high temperatures? - ANSWER Hydrogen bonding bonds the water molocules closer together. What is an ampipathic molecule? give an Example. - ANSWER A molecule with both hydrophobic and hydrophilic regions. Example: PhoshpoLipid (Phospho=philic,lipid= phobic) What is a lipid? - ANSWER A lipid is a biological molecule with low solubility in water. Lipid means fat. Liposuction is fat removal. Peptides are NOT lipids. What are the 6 major groups of lipids? - ANSWER 1) fatty acids... the next 3 have a 3-carbon back bone: 2) Tri-glyceride 3) Phospholipids 4) Glycolipids 5) Steroids 6) Terpenes - A large class of organic compounds. examples: smelly pine oils, beer hops aroma and vitamin A. What is the structure of a Tri-glyceride? - ANSWER triglicerides are esters. Composed from 3 carbon glycerol backbone and 3 fatty acid chains dangling. Each carbon chain is attached by an ester bond. What happens if you add water to an ester group in a Tri-glyceride? How is this reaction rate increased? - ANSWER Water cleaves the ester bond into an alcohol and a carboxylic/ fatty acid. LIPASES speed are the enzyme that speed this reaction. in terms of water solubility, What is important to know about the longer the carbon chain in a Tri-glyceride when broken down? - ANSWER longer carbon chains are less water soluble. In longer chains the polar carboxylic acid are less significant. How soluble is a Shorter chain fatty acids? - ANSWER Shorter chain fatty acids are slightly water soluble. explain what is so special about Saturated Fatty Acids........Also, explain the melting point. - ANSWER saturated fatty acids have only single, alkane bonds along the carbon chain. They have a straighter chain and have more van der wall forces, and therefor a higher melting point. explain what is so special about Unsaturated Fatty Acid.... Also, explain the melting point. - ANSWER Unsaturated fatty acids have at least one double bond. They are not saturated with Hydrogen. they have a LOWER melting point. At room temperatures unsaturated fatty acids may be oily, like Healthy peanut butter. explain the phospho-lipids structure. Where are phoshpo lipids common? - ANSWER Phospholipids are also built on a 3 Carbon backbone. One of the carbon has a Phosphate PO4 group. the other 2 carbons have carbon chains attached by a ester bond. This is the lollypop of the cell membrane. Esters have 2 oxygens. What regions are poplar nonpolar in a membrane? - ANSWER 1)the phosphates are Polar, water lovin, hydro philic regions that face the outside. 2) Nonpolar, hydro phobic carbon chain regions face the inside. Explain glycolipids structure. - ANSWER glycolipids have 3 carbon backbone with 2 Carbon chains attached by an ester group. THe third carbon has a carbohydrate What do steroids look like? - ANSWER Slightly amphipathic 4 ring structures lipids are insoluble. So how do they move through the blood? - ANSWER They are usually carried by lipoproteins, like HDL or LDL. What are the major classes of lipoproteins? - ANSWER 1) Chylomicrons which are the largest 2) VLDLs these are low denstiy, but large. 3) LDLs 4) HDLs. these high density lipids are the smallest, and called good proteins. What are proteins made up of? - ANSWER one or more chains of amino acids, perhaps in a crazy ass arrangement. describe amino acid structure. - ANSWER Amino acids have 4 parts attached to the alpha carbon. 1. the amino group, which is NH2 2. the R group, which is one of 20 choices 3. the Carboxylic acid or C O O the last thing attached to the Carbon is the Hydrogen. What are the basic amino acids? - ANSWER Hal Histidine Arginine Lysine What are the acidic amino acids? - ANSWER Aspartic acid and Glutamic acid What are the nonpolar amino acids? - ANSWER Poor LTMG Is Venezuelan At Parties 1) Phenylalanine 2) Leucine 3) Tryptophan 4) Methionine 5) Glycine 6) Isoleucine 7) Valine 8) Alanine 9) Proline What is the primary structure of a protein? - ANSWER Sequence of amino acids and Location of disulfide bonds between cistine residues What is the secondary structure of a protein? - ANSWER 1) Twisting of the alpha helix 2) Beta sheets What is the tertiary structure of a protein? - ANSWER 3D structure including bending What is the quaternary structure of a protein? - ANSWER Multiple proteins in formation What are the five forces that create tertiary structure? - ANSWER 1) Covalent 2) Disulfide bonding between cysteine residues (Bond itself creates tertiary structure) 3) H bonds 4) HPhob away from cytosol and Hphil interactions towards cytosol 5) Van Der Waals (dipoles, instantaneous dipoles) What levels of structure are disrupted during the denaturation process? - ANSWER Secondary - quaternary What is the difference between a proteoglycan and a glycoprotein? - ANSWER Glycoproteins: 1) Made of protein and carbohydrate 2) More stable than proteins 3) Often used in IS to bridge the cellular membrane. 4) Ratio - have more proteins Proteoglycans: [Show More]

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