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CHM 140
Exam III
| Question | Answer |
|---|---|
| carbohydrate- | a polyhydroxyaldehyde/ketone, or a substance that gives these compounds on hydrolysis |
| ketose- | monosaccharide containing a ketone group |
| pentose- | Five-carbon monosaccharide |
| mutarotation – | change from alpha to beta or beta to alpha forms in the ring structure of monosaccharides |
| What is the general molecular formula for monosaccharides? | CnH2nOn |
| The two polysaccharides that make up starch are amylose and amylopectin. What is the structure of amylose, the monosaccharide units that make up the polymer, the type of linkage between the monosaccharide units, and overall shape of the polysaccharide} | Amylose contains chains up to 4,000 D-glucose units joined by a-1,4-glycosidic bonds giving a linear structure to the molecule |
| Glycogen is stored in the body in the ___ and ___ | muscle, liver |
| What is the structure of glycogen, the monosaccharide units that make up the polymer, the type of linkage between the monosaccharide units, and overall shape of the polysaccharide? | Glycogen contains chains up to 1,000,000 D-glucose units joined by a-1,4-glycosidic bonds with branching started by -1,6-glycosidic bonds giving a highly branched structure to the molecule |
| Cellulose is the most widely distributed plant structural material. What is the structure of cellulose, the monosaccharide units that make up the polymer, the type of linkage between the monosaccharide units, overall shape of the polysaccharide. | Cellulose contains chains up to 2,200 D-glucose units joined by a-1,4-glycosidic bonds giving a linear structure to the molecule |
| Sucrose is made up of what two monosaccharides? ___and ___ | glucose, fructose |
| Lipids differ in many of their structures. By what criteria are lipids grouped together? | common solubility properties-soluble in organic solvents |
| Which of the following groups would be hydrophilic (A) or hydrophobic (B). R–CH=CH2__ R – NH3+Cl- __ R-OH __ R–CH2–CH3__ | B, A, A, B |
| What are the 3 major roles of lipid in the body? | Energy storage, chemical messengers, cell membrane components |
| Where are triglycerides stored in the body? | adipose tissue or fat cells |
| Why do triglycerides with mainly saturated fatty acids chains have a higher melting point thantriglycerides with a high percentage of unsaturated fatty acids? | Saturated fatty acids stack neater and closer together due to similar chain structure. Unsaturated fatty acids are a mixture of saturated and unsaturated fatty acids and do not stack as well hence the London forces between the fatty acids is less |
| Describe the structure of a triglyceride. | Triester of glycerol and 3 fatty acid chains |
| What chemical class do triglycerides belong to? | esters |
| Draw the structure of sphingosine. | CH3(CH2)12CH=CHCH(OH)CHNH2CH2OH |
| What are the two main functions of cholesterol? | cell membrane component and precurer of steroid derivatives (bile salts and hormones) |
| Which cholesterol complexes (HDL or LDL) is called "good cholesterol" and "bad chloesterol"? Explain why they are “good” and why they are “bad”. | HDL "good" transports cholesterol to liver for excretion as bile salts and formation of hormones, reducing serum levels. LDL "bad" high levels=not enough LDL being absorbed into cells and remains in serum to deposit on the walls of blood vessels; artheros |
| Name a male sex hormone? What is its function? | testosterone or androsterone-responsible for development of secondary sexual characteristics |
| What are the two main female sex hormones? What are their two functions? | estradiol and progesterone-development of secondary sexual characteristics and control of the menstrual cycle |
| What is the function of aldosterone? | mineralcorticoid-enhances Na+ and Cl- reabsorbtion and increased excretion of K+ by the kidneys. |
| What are the two main functions of bile salts? | elimination route of cholesterol and emulsify fats and aid their absorbtion in the intestines |
| Where are bile salts synthesized? | liver |
| Where are the bile salts stored? | gallbladder |
| What precursor is prostaglandins, thromboxanes, and leukotrienes synthesized from? | Arachidonic acid - a 20 carbon unsaturated fatty acid |
| What is the function of thromboxanes in the blood? | induces platlets aggregation and vessel constriction |
| Both prostaglandins and leukotrienes cause what physiological response at an injury site? | inflammation |
| Describe how cholesterol is transported from the liver to the peripheral tissue cells | Leaves liver as VLDL composed of cholesterol esters and triglycerides. As TG are deposited in fat cells, VLDL becomes LDL. LDL binds to specific receptors on cell surface and enters cells where it is broken down to cholesterol and esters |
| isoelectric point- | pH at which a molecule in solution has no net charge |
| denaturation- | process of destroying the native conformation of a protein (its shape) by chemical or physical means |
| secondary structure- | conformations of amino acids in localized regions of a polypeptide chain |
| tertiary structure- | overall conformation of a polypeptide chain |
| quaternary structure- | arrangement of two or more polypeptide chains into noncovalently bonded aggregation |
| The most abundant protein found in the body is | collagen |
| List 8 functions of proteins in the body | Storage Catalysts Movement Transport Hormone Protection Structure Regulation |
| Where in the body is the protein elastin found? | ligaments |
| What are the two types (shapes) of proteins and what is the structure of each? | fibrous-long, linear, ropelike globular-compact, spherical |
| Describe in detail the structure of the a-helix, position of C=O and N-H groups, position of the R groups and interactions between groups which hold the helix in its shape | N-H groups point to sprial helix parallel to axis, C=O groups point in oppositedirection, R-group perpendicular to helix of axis hydrogen bonding between the amine hydrogen and carbonyl group hold the helix in its spiral shape. |
| Why is an amino acid as good buffer? | An amino acid reacts with acid (H3O+) and base (OH-) to take them out of the solution and maintain the pH as a constant value |
| Describe the structure of collagen | Collagen consists of three polypeptide helical chains wrapped around each other in a ropelike twist to form a triple helix called tropocollagen. Each polypeptide is a helix but not an a-helix. The three chains are held together by hydrogen bonding |
| What 4 interactions hold the protein in its tertiary structure? | covalent bonds, hydrogen bonding, salt bridges and hydrophobic interactions |
| What two amino acids form the dipeptide? | alanine and glycine |
| What name is given to a molecule like this which contains two charges | zwitterion |
| substrate- | compounds whose reaction an enzyme catalyzes |
| noncompetitive inhibition- | any substance that binds to a portion of the enzyme other than the active site and thus inhibits the activity of the enzyme |
| isoenzyme- | enzyme that occurs in multiple forms; each catalyzes the same reactio |
| competitive inhibition- | substance that binds to the active site of an enzyme thus preventing binding of substrate |
| proenzyme- | an inactive form of an enzyme that must have part of its polypeptide chain cleaved before it becomes active |
| allosterism- | type of enzyme regulation based on an event occurring on the enzyme at a place other than the active site but that creates a change in the active site |
| positive modulation- | stimulation of an allosteric enzyme |
| regulator- | substance that binds to an allosteric enzyme and causes either positive or negative modulation |
| apoenzyme- | protein part of enzyme |
| Name the six major groups or classification of enzymes | Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases |
| cofactor- | non protein part of enzyme |
| coenzyme- | organic molecule |
| Describe the difference between the lock and key model and the induced fit model of substrate-enzyme interaction. | Lock and key model, enzyme and substrate are rigid 3D models, substrate fits in active site like a key in a lock.Induced fit model is flexible model of enzyme where active site becomes modified to accommodate substrate like a hand being put in a glove |
| What 5 amino acids are generally found in the active sites of most enzymes? | Glutamic acid Arginine Cysteine Histidine Aspartic acid |
| Describe how a regulator works to control enzyme activity. | 1Regulator binds to an allosteric enzyme at a site other than the active site 2This binding changes the shape of the active site. 3Regulator may act as an inhibitor (negative modulation) or a stimulator (positive modulation |
| Explain why enzyme inhibition by the feedback mechanism is important. | The feedback mechanism would provide a mechanism to prevent the overproduction of product D and/or the depletion of reactant A which might have either wasteful or harmful effects. |
| Poisons work in different ways in the cells to cause harmful effects. How might enzyme inhibition be involved? | Many poisons act by binding irreversibly to enzymes to destroy the enzyme’s function.IE poison cyanide inhibits enzyme cytochrome c oxidase, which effectively blocks cellular respiration. Heavy metals also bind irreversibly to enzymes destroyingfunctions. |
Created by:
fallsummerspring
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