Why are all of the a-amino acids except glycine chiral?
> If enzyme active sites are small, why are enzymes so large?
> What chemical reaction is mediated by each of the enzymes in Question 19.3? Question 19.3: What is the substrate for each of the following enzymes? a. Sucrase b. Pyruvate decarboxylase c. Succinate dehydrogenase
> How does the rate-limiting step influence an enzymecatalyzed reaction?
> Why doesn’t the rate of an enzyme-catalyzed reaction increase indefinitely when the substrate concentration is made very large?
> What is the effect of an enzyme on the activation energy of a reaction?
> List the six classes of enzymes based on the type of reaction catalyzed. Briefly describe the function of each class, and provide an example of each.
> Give a systematic name for the enzyme that would act on each of the following substrates: a. Alanine b. Citrate c. Ampicillin d. Ribose e. Methylamine
> Draw the structural formula of the peptide trp-val-lys-ala-ser. Show which bonds would be cleaved by trypsin, chymotrypsin, and elastase.
> What is the IUPAC name for each of the fatty acids in Question 17.1? (Hint: Review the naming of carboxylic acids in Section 14.1, and Table 17.1.) Question 17.1: Draw formulas for each of the following fatty acids: a. Oleic acid b. Lauric acid c. Li
> Draw the structural formulas of the following peptides, and show which bond would be cleaved by chymotrypsin. a. trp-val-gly b. phe-ala-pro
> By comparing two solutions: 0.50 M sodium chloride (an ionic compound) and 0.50 M sucrose (a covalent compound). Calculate the boiling temperature of each solution. Assume that the molality of each solution is 0.50 m. (The molar and molal concentrations
> How can structural analogs serve as enzyme inhibitors?
> Explain the difference between an irreversible inhibitor and a reversible, competitive inhibitor.
> What are the coenzymes formed from each of the following vitamins? What are the functions of each of these coenzymes? a. Pantothenic acid b. Niacin c. Riboflavin
> Name some ethnic foods that apply the principle of mixing vegetable proteins to provide all of the essential amino acids.
> Write an equation representing the action of the proteolytic enzyme trypsin. (Hint: In order to write the structure of a dipeptide that would be an appropriate reactant, you must consider what is known about where trypsin cleaves a protein chain.)
> Define the term incomplete protein.
> Define the term nonessential amino acid.
> Wine is made from the juice of grapes by varieties of yeast. The yeast cells produce ethanol as a by-product of their fermentation. However, when the ethanol concentration reaches 12–13%, all the yeast die. Explain this observation.
> Where in the body do you find glycogen stored?
> What are the possible side effects of cortisone treatment?
> In step 10 of glycolysis, phosphoenolpyruvate is converted to pyruvate, and ATP is produced by substrate level phosphorylation. How is this reaction bypassed in gluconeogenesis?
> How is oxygen efficiently transferred from mother to fetus?
> The blood of the horseshoe crab is blue because of the presence of a protein called hemocyanin. What is the function of hemocyanin?
> Write an equation representing the binding to and release of oxygen from hemoglobin.
> What is the function of myoglobin?
> Why are glycosidic bonds acetals?
> Draw the structure of a lecithin molecule in which the fatty acyl groups are derived from arachidic acid.
> What is a prosthetic group?
> What weak interactions are responsible for maintaining quaternary protein structure?
> Write a complete equation for the acid hydrolysis of butyl acetate. Write the IUPAC name for each of the organic reactants and products.
> Why is the amino acid proline often found in the random coil hinge regions of the tertiary structure?
> a. Calculate the boiling temperature of 1.50 m urea, N2H4CO. Urea is a covalent compound. b. Calculate the boiling temperature of 1.50 m LiBr, an ionic compound.
> What is the role of cystine in maintaining protein structure?
> What is a Haworth projection?
> Compare a parallel b-pleated sheet to an antiparallel b-pleated sheet.
> What is the relationship between the structure of fibrous proteins and their functions?
> Describe the forces that maintain the two types of secondary structure: a-helix and b-pleated sheet.
> What are the two most common types of secondary structure?
> Write a balanced equation showing peptide bond formation between threonine and aspartate.
> Explain the relationship between the primary structure of a protein and the gene for that protein.
> What type of bond joins the amino acids to one another in the primary structure of a protein?
> Write the structure of each of the following peptides at pH 7: a. Glycyl-valyl-serine b. Threonyl-cysteine c. Isoleucyl-methionyl-aspartate
> Of what value are restriction enzymes in recombinant DNA research?
> Using line formulas, write an equation for the hydrogenation of all cis-4,7,10,13,16,19-docosahexaenoic acid.
> Draw the resonance hybrids that represent the peptide bond.
> Write an equation for the acid hydrolysis of a triglyceride containing three capric acid molecules.
> Write the structures of the positively charged amino acids. Indicate whether you would expect to find each on the surface or buried in a globular protein.
> What are the common and IUPAC names of each of the following fatty acids? a. CH3(CH2)5CH ——CH(CH2)7COOH b. CH3(CH2)7CH ——CH(CH2)7COOH
> Why are amino acids zwitterions at pH 7.0?
> Draw the d- and l-isomers of valine. Which would you expect to find in nature?
> Provide two examples of proteins that are required for movement.
> What is the function of regulatory proteins?
> Describe the steps used in writing the net ionic equation for a reaction.
> A solution of Na2CO3 is mixed with a solution of CaCl2. A white precipitate is formed. Write the net ionic equation for the reaction, and identify the white precipitate.
> List some natural sources of carbohydrates.
> What are the functions of structural proteins?
> Define the term antibody.
> What are some common sources of dietary protein?
> What biological molecules contain pyrimidine rings?
> Write a balanced equation for the hydrogenation of 2-hexenoic acid.
> Explain the evidence for a relationship between gaminobutyric acid and aggressive behavior.
> Describe the fluid mosaic model of membrane structure.
> What is the correlation between saturated fats in the diet and atherosclerosis?
> What symptoms are associated with a deficiency of serotonin?
> What is the physiological function of gluconeogenesis?
> What is the function of norepinephrine?
> Draw the five-carbon isoprene unit.
> What is a terpene?
> Write a complete equation for the reaction of methyl butyrate and NaOH. Write the IUPAC name for each of the organic reactants and products.
> How has our understanding of the steroid sex hormones contributed to the development of oral contraceptives?
> How does cholesterol contribute to atherosclerosis?
> Why are sphingomyelins amphipathic?
> In addition to HCl, what is the product of the reaction of a primary amine with an acid chloride? Draw the structure of that product and describe its features.
> What are the two major types of sphingolipids?
> Draw one possible structure of a triglyceride that contains the three fatty acids capric acid, lauric acid, and arachidonic acid.
> Solutions containing Mg(NO3)2(aq) and NaOH(aq) are mixed. Will a precipitate form? If so, write its formula.
> What do you predict the physical state would be of a triglyceride with three unsaturated fatty acid tails? Explain your reasoning.
> Why are triglycerides also referred to as triacylglycerols?
> Define the term phosphatidate.
> What is the recommendation of the National Institutes of Health for intake of DHA, EPA, linoleic acid, and linolenic acid?
> List some foods that are good sources of a-linolenic acid.
> What foods are good sources of EPA and DHA?
> What are the functions of thromboxane A2 and leukotrienes?
> What is the role of prostaglandins in the inflammatory response?
> What molecules are formed from arachidonic acid?
> Write an equation for the esterification of glycerol with a molecule of capric acid, a molecule of oleic acid, and a molecule of stearic acid.
> a. Define feedback inhibition. b. Describe the role of allosteric enzymes in feedback inhibition. c. Is this positive or negative allosterism?
> Write an equation for the base-catalyzed hydrolysis of a triglyceride containing a molecule of palmitoleic acid, a molecule of oleic acid, and a molecule of palmitic acid.
> Write the complete equation for the esterification of arachidic acid and ethyl alcohol. Write the IUPAC name for each of the organic reactants and products.
> Write equations for the reactions of lauric acid and linoleic acid with KOH.
> Write an equation for the esterification of glycerol with three molecules of palmitic acid.
> Draw the structures of each of the following fatty acids: a. trans-5-Decenoic acid b. cis-5-Decenoic acid
> What is an aldotriose?
> As the number of carbon-carbon double bonds in fatty acids increases, what is the effect on the melting point?
> Write the structures for a saturated and an unsaturated fatty acid.
> Why are lipids (triglycerides) such an efficient molecule for the storage of energy in the body?
> What is the role of lysosomes in the metabolism of plasma lipoproteins?
> Why is resonance an important concept in bonding?
> What is meant by the term fused ring?
