MCAT Biology Practice Questions with Merged Answers for Exam revisions

The chemical reaction that breaks down all the major macro-molecules - AnsHydrolysis What is the strongest type of INTER-molecular bonds? - AnsHydrogen bonds are the strongest intermolecular bonds.... o dipole-dipole bonds are weaker. . . Vander wall bonds are the weakest. Why is water a liquid at high temperatures? - AnsHydrogen bonding bonds the water molecules closer together. What is an amphipathic molecule? give an Example. - AnsA molecule with both hydrophobic and hydrophilic regions. Example: PhoshpoLipid (Phospho=philic,lipid= phobic) What is a lipid? - AnsA lipid is a biological molecule with low solubility in water. o Lipid means fat. Liposuction is fat removal. o Peptides are NOT lipids. What are the 6 major groups of lipids? - Ans1) fatty acids... the next 3 have a 3-carbon back bone: o 2) Tri-glyceride o 3) Phospholipids o 4) Glycolipids o 5) Steroids o 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? - Anstriglicerides 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? - AnsWater 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? - Anslonger carbon chains are less water soluble. o In longer chains the polar carboxylic acid are less significant. How soluble is a Shorter chain fatty acids? - AnsShorter chain fatty acids are slightly water soluble. explain what is so special about Saturated Fatty Acids........Also, explain the melting point. - Anssaturated 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. - AnsUnsaturated fatty acids have at least one double bond. They are not saturated with Hydrogen. they have a LOWER melting point. o At room temperatures unsaturated fatty acids may be oily, like Healthy peanut butter. explain the phospho-lipids structure. Where are phoshpo lipids common? - AnsPhospholipids are also built on a 3 Carbon backbone. o One of the carbon has a Phosphate PO4 group. the other 2 carbons have carbon chains attached by a ester bond. o This is the lollypop of the cell membrane. Esters have 2 oxygens. What regions are poplar nonpolar in a membrane? - Ans1)the phosphates are Polar, water lovin, hydro philic regions that face the outside. o 2) Nonpolar, hydro phobic carbon chain regions face the inside. Explain glycolipids structure. - Ansglycolipids have 3 carbon backbone with o 2 Carbon chains attached by an ester group. o THe third carbon has a carbohydrate What do steroids look like? - AnsSlightly amphipathic 4 ring structures lipids are insoluble. So how do they move through the blood? - AnsThey are usually carried by lipoproteins, like HDL or LDL. What are the major classes of lipoproteins? - Ans1) Chylomicrons which are the largest o 2) VLDLs these are low denstiy, but large. o 3) LDLs o 4) HDLs. these high density lipids are the smallest, and called good proteins. What are proteins made up of? - Ansone or more chains of amino acids, perhaps in a crazy ass arrangement. describe amino acid structure. - AnsAmino acids have 4 parts attached to the alpha carbon. o the amino group, which is NH2 o the R group, which is one of 20 choices o the Carboxylic acid or C O O o the last thing attached to the Carbon is the Hydrogen. What are the basic amino acids? - AnsHal o Histidine o Arginine o Lysine What are the acidic amino acids? - AnsAspartic acid and Glutamic acid What are the nonpolar amino acids? - AnsPoor LTMG Is Venezuelan At Parties o Phenylalanine o Leucine o Tryptopha