Biochemistry 3050 Spring 2014 Exam 1 Name 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 bonds b van der Waals forces c hydrogen bonds d hydrophobic interactions e 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 bonds b van der Waals forces c covalent bonds d e hydrophobic interactions ionic 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 structural complementarity e Hydrogen van der Waals and hydrophobic interactions do not form linear bonds 1 Biochemistry 3050 Spring 2014 Exam 1 Name 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 e A hydrogen bond is weaker than van der Waals forces It is a type of covalent bond 7 Electrostatic forces a include ionic interactions between negatively charged carboxyl groups and positively charged amino groups b average about 2 kJ mol in aqueous solutions typically are directional like hydrogen bonds c require a precise fit like van der Waals interactions d include ionic induced dipole and permanent dipole interactions e 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 Lysine b NADH c Ascorbic acid d RNA e None of the above denaturation occurring in all EXCEPT a dramatic increase in temperature b change in ionic strength c d addition of strong acid or base e none all will denature biological macromolecules refrigeration 2 10 Biological molecules are functionally active only within a narrow range of environmental conditions with Biochemistry 3050 Spring 2014 Exam 1 Name 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 ionic interaction amine a b ionic interaction ketone c hydrogen bond alcohol d hydrogen bond aldehyde e both a and c are correct 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 15 Because of its highly polar nature water is an excellent solvent for polar substances but NOT for 16 The solvent with the highest dielectric constant in this group is intermolecular attractions unique to water a 1 b 2 c 3 d 4 e 5 a salts b sugars c aldehydes and ketones d hydrocarbons e alcohols and amines a water b acetic acid c ethanol d hexane e benzene 3 19 The H bonded water around an ionic substance tends to and the H bonded water around nonpolar Biochemistry 3050 Spring 2014 Exam 1 Name CUemail 17 Hydrogen bonds in ice are all EXCEPT a directional b straight c weak d e holding water molecules in ice apart responsible for the lower density of ice over liquid water 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 solutes tends to inhibit ionization promote hydrophobic interactions a b inhibit ionization inhibit hydrophobic interactions c not impact ionization inhibit hydrophobic interactions d promote ionization not impact hydrophobic interactions e promote ionization promote hydrophobic interactions 20 Amphiphilic amphipathic molecules include sugars a b acidic amino acids c inorganic salts d water e salts of fatty acids 21 In micelles a polar ends form hydrophobic interactions with water b nonpolar ends form hydrophilic interactions with water c hydrocarbon tails form hydrophobic interactions with water d polar ends are hydrophobic and nonpolar ends are hydrophilic e hydrocarbon tails are excluded from the water into hydrophobic domains
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