Biochemistry 3050, Spring 2014 Exam 1Name_________________________________CUemail__________________Multiple Choice (2 pnts each). Write the letter of the correct answer in the space provided AND THEN fill in the correct Bubble on the ORANGE Scantron!______1. The structural integrity of supramolecular complexes (assemblies) of multiple components are bonded to each other by all of the following forces EXCEPT:a. covalent bondsb. van der Waals forcesc. hydrogen bondsd. hydrophobic interactionse. ionic interactions______2. Membrane structures are maintained primarily by:a. hydrophobic interactions.b. covalent bonds.c. hydrogen bonds.d. non-spontaneous assembly.e. ionic interactions.______3. Alpha helices are stabilized primarily by:a. hydrogen bonds between the main chain peptide bond component atoms.b. electrostatic interactions between R-groups.c. hydrophobic interactions between the -carbons of the main chain.d. hydrogen bonding between the R-groups.e. hydrophobic interactions between R-groups and the solvent water.______4. Weak forces that create constantly forming and breaking interactions at physiological temperatures, but cumulatively impart stability to biological structures generated by their collective activity include all EXCEPT:a. hydrogen bondsb. van der Waals forcesc. covalent bondsd. ionic interactionse. hydrophobic interactions______5. Which of the following is a true statement about non-covalent bonds?a. They are all the result of electron sharing.b. Hydrogen bonds, ionic bond and hydrophobic interactions all carry a degree of specificity while van der Waals interactions are induced.c. All noncovalent bonds are formed between oppositely charged polar functions.d. Van der Waals interactions are not affected by structural complementarity, while hydrogen bonds, ionic bonds and hydrophobic interaction are affected by structuralcomplementarity.e. Hydrogen, van der Waals, and hydrophobic interactions do not form linear bonds.1Biochemistry 3050, Spring 2014 Exam 1Name_________________________________CUemail________________________6. Which of the statements about the nature of the hydrogen bond is true?a. The donor is a hydrogen atom bonded to a carbon.b. The more linear the bond, the stronger the interaction.c. The acceptor must be similar in electronegativity to hydrogen.d. It is a type of covalent bond.e. A hydrogen bond is weaker than van der Waals forces.______7. Electrostatic forcesa. include ionic interactions between negatively charged carboxyl groups and positively charged amino groups.b. average about 2 kJ/mol in aqueous solutions.c. typically are directional like hydrogen bonds.d. require a precise fit like van der Waals interactions.e. include ionic, induced dipole and permanent dipole interactions.______8. All are true about hydrophobic interactions EXCEPT:a. Hydrophobic interactions result from the strong tendency of water to exclude nonpolar groups or molecules.b. Hydrophobic interactions result because water molecules prefer the stronger interactions that they share with one another, compared to their interactions with nonpolar molecules.c. Hydrophobic interactions result from hydrogen bonds between water and the hydrophobic molecules.d. The preferential interactions between water molecules "exclude" hydrophobic substances from aqueous solution and drive the tendency of nonpolar molecules to cluster together.e. Hydrophobic interactions result in nonpolar regions of biological molecules being buried in the molecule's interior to exclude them from the aqueous milieu.______9. A mutation in gulonolactone oxidase results in the inability of humans to sythezize what?a. Lysineb. NADHc. Ascorbic acidd. RNAe. None of the above______10. Biological molecules are functionally active only within a narrow range of environmental conditions withdenaturation occurring in all EXCEPT:a. dramatic increase in temperature.b. change in ionic strength.c. refrigeration.d. addition of strong acid or base.e. none, all will denature biological macromolecules.2Biochemistry 3050, Spring 2014 Exam 1Name_________________________________CUemail________________________11. All are true for prokaryotic cells EXCEPT:a. Some have flagella.b. They have a simple plasma or cell membrane.c. They posses a distinct nuclear area, but no nucleus.d. They have ribosomes, but no mitochondria.e. All are true.______12. A carboxylic acid at pH 7.4 would most likely form a(n) ___________ with a(n) ____________. a. ionic interaction / amine d. hydrogen bond / aldehydeb. ionic interaction / ketone e. both a and c are correctc. hydrogen bond / alcohol______13. Properties of water that render it so suited to its role as a medium of life include all EXCEPT:a. Unrivaled ability to form hydrogen bonds.b. Unusually high dielectric constant of water explains water's ability to surround ions and increase the ions' attraction for one another.c. Unparalleled ability to orient around nonpolar solutes to promote hydrophobic interactions.d. The small, but significant, tendency to form H+ and OH ions.e. None, all are true.______14. The unrivaled ability to form ____ hydrogen bonds per liquid water molecule is the source of the strong intermolecular attractions unique to water.a. 1b. 2c. 3d. 4e. 5______15. Because of its highly polar nature, water is an excellent solvent for polar substances, but NOT for:a. salts.b. sugars.c. aldehydes and ketones.d. hydrocarbons.e. alcohols and amines.______16. The solvent with the highest dielectric constant in this group is:a. water.b. acetic acid.c. ethanol.d. hexane.e. benzene.3Biochemistry 3050, Spring 2014 Exam 1Name_________________________________CUemail________________________17. Hydrogen bonds in ice are all EXCEPT:a. directional.b. straight.c. weak.d. responsible for the lower density of ice over liquid water.e. holding water molecules in ice apart.______18. Pure liquid water consists of H2O molecules:a. held in a rigid three-dimentional network.b. with local preference for linear geometry.c. with large numbers of strained or broken hydrogen bonds.d. which do not switch H-bonds readily.e. all are true.______19. The H-bonded water around an ionic substance tends to ____; and the H-bonded water around nonpolar solutes tends to ____.a. inhibit ionization, promote hydrophobic interactionsb. inhibit ionization, inhibit hydrophobic interactionsc. not impact ionization, inhibit hydrophobic interactionsd. promote ionization, not impact hydrophobic interactionse.
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