100 Biochemistry Exam 1 Questions with correct answers. Graded A

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100 Biochemistry Exam 1 Questions with correct answers Which of the following is found in RNA but not DNA A) Uracil B) Guanine C) Deoxyribose D) Phosphate E) Adenine >>>>Uracil Which of the fo... llowing amino acids exhibits significant ultraviolet absorption above 250 nm? A) Alanine B) Tyrosine C) Methonine D) Glycine E) All of the above >>>>Tyrosine Collagen fibers have a high content of which amino acids? A) histidine, tyrosine, and proline B) proline, hydroxyproline, and tyrosine C) Alanine, phenalanine, and isoleucine D) Cysteine, Methionine, and Phenalenine E) Glycine, proline, and hydroxyproline >>>>glycine, proline and hydroxylproline At neutral pH (7) A) the carboxyl group exists as -COOH, and the amino group exists as -NH3+ B) the carboxyl group exists as -COO-, and the amino group exists as -NH3+ C) the carboxyl group exists as -COO-, and the amino group exists as -NH2- D) the carboxyl group exists as -COOH, and the amino group exists as -NH2- E) None of the above >>>>the carboxyl group exists as -COO-, and the amino group exists as -NH3+ The basic structural unit of collagen, tropocollagen, has the following structure: A) triple stranded extended helix B) Beta-pleated sheet C) Right handed alpha-helix D) Left handed alpha helix E) A mix of alpha helicies and beta pleated sheets >>>>triple stranded helix Which of the following amino acids has the largest tendency to destabilize alpha helicies? A) Arginine B) ProlineC) Tyrosine D) Serine E) Histidine >>>>proline In a DNA double helix, the two DNA chains are held together by: A) Covalent bonds between the pair of bases B) Hydrogen bonds between the pair of bases C) Ionic bonds D) Osmotic Interactions E) None of the aboce >>>>Hydrogen Bonds In DNA, guanine pairs with A) Adenine B) Cytosine C) Thymine D) Guanine E) Uracil >>>>Cytosine Which of the following amino acids are neutral and polar at pH=7 A) Tyrosine B) Serine C) Asparagine D) Threonine E) All of the above >>>>all of the above The partial double bond character of the peptide bond: A) restricts rotation around the C-N bond B) Allows rotation around the C-N bond C) Restricts rotation around the Ca-C bond D) Restricts rotation around the Ca-N bond E) allows free rotation around C-N and C-C bonds >>>>restricts rotation around the C-N bond Which of the following amino acids has a sulfur atom A) lecuine, serine B) methionine, cysteine C) aparagine, glutamine D) arginine, lysine E) tyrosine, phenylalanine >>>>B) methionine, cysteine Which of the following is true about buffer systems? A) they are typically made up of a strong acid and strong base mixed together B) The pH will vary greatly in the region of the titration curve where [HA]=[A-] C) They will have an area on their titration curve where the greatest buffering capacity exists D) They will vary greatly in pH as acid or base is addedE) None >>>>C) They will have an area on their titration curve where the greatest buffering capacity exists When complex biomolecules such as proteins are unfolded and disordered from their biologically active or native forms the process is referred to as A) Culmination B) de-energization C) Hydrolysis D) denaturation E) Desorption >>>>denaturation If one cell has AT contents 40% what will be the percentage of guanine residues? A) 45% B) 15% C) 30% D) 50% E) Cannot be calculated >>>>C) 30% Hydrogen bonds can form between: A) hydrogen atom covalently bonded to an electronegative atom and a second electronegative atom B) A nitrogen atom covalently bonded to an electronegative atom and a nitrogen atom on another molecule C) A hydrogen atom ionically bound to an electropositive aotm and a second electronegative atom D) A covalently coupled to an electropositive atom and a second electronegative atom >>>>A) hydrogen atom covalently bonded to an electronegative atom and a second electronegative atom A Ramachandran Diagram: A) Indicates where the Van der Waals interactions are in a protein B) indicates where electrostatic interactions are stabilizing a protein C) indicates the sterically reasonable values of the angles phi and (weird u shaped greek letter) D) Indicates the sterically unreasonable values of phi and greek letter u E) A & B >>>>indicates the sterically reasonable values of angles phi and (weird u shaped greek letter) Which of the following noncovalent interactions are NOT important in protein structure? A) hydrophobic interactions B) Ionic Bonds C) Disulfide Bonds D) van deer Waals forces E) Hydrogen Bonds >>>>Ionic BondsThe net attraction that nonpolar solute molecules experience for one another in water is called: A) colligative interaction B) osmotic pressure C) semipermeability D) hydrophobic interaction E) hydrophilic interaction >>>>Hydrophilic interaction If Delta G for a reaction is negative, then: A) Delta S is always negative B) Delta S is always positive C) Delta S can be either negative or positive D) Delta H is always positive E) Delta H is always negative >>>>Delta S can be negative or positive The pH of a solution with a hydroxyl ion concentration of 4x10^-3 is: A) 11.6 B) 3.6 C) 2.4 D) 10.4 E) 12.6 >>>>11.6 Which of the following statements are true about an alpha helix? A) The side chains extended outward from the core structure of the helix B) All of the H-bonds lie parallel to the helix axis C) All of the carbonyl groups point in one direction D) All of the above E) Only A and C >>>>A and C Which of the following is a nonpolar amino acid? A) Isoleucine B) Valine C) Methionine D) Phenylalanine E) Arginine >>>>arginine What property of water best explains its excellent solvent abilities for ionic substances? A) low BP B) highly polar nature C) Low dielectric constant D) The 109 degree H-O-H bond angle E) All of the above >>>>highly polar nature There are ___ commonly occurring amino acids A) 4 B) 5C) 40 D) 20 E) none of the aboce >>>>20 The peptide linkage between amino acids has partial double bond character. Because of this: A) There is free rotation around the peptide bond B) The carbonyl group and amino groups always reside on the same side of the bond C) The cis conformation is favored D) Only L-amino acids are found in nature E) There is restricted rotation around the peptide bond >>>>there is restricted rotation around the peptide bond The 5' and 3' numbers are related to the A) length of the DNA strand B) Carbon numbers in sugar C) number of phosphates D) Base Pair rule E) Chargoff's RUle >>>>Carbon numbers in sugar Most proteins absorb light at a wavelength of 280 nm. Which of the following amino acids is primarily responsible for this absorption? A) Glycine B) Histidine C) Proline D) Tryptophan E) Cysteine >>>>Tryptophan Which of the following principles is false? A) The chemical shift of amino acid protons depends on their chemical environment B) The chemical shift of amino acid protons depends on the state of ionization C) The change in electron density during a titration is not transmitted throughout the carbon chain in the aliphatic amino acids and aliphatic protons of aromatic amino acids D) The magnitude of the coupling constants between protons and adjacent carbons depends in some cases on the ionization state of the amino acid E) A and C >>>>A A heteromultimeric protein: A) contains only one polypeptide chain B) Contains multiple copies of the same polypeptide chain C) Contains modified amino acids in the polypeptide chains D) Contains multiple polypeptide chains and can be cross-linked by disulfide bridges >>>>Contains multiple polypeptide chains and can be crosslinked by disulfide bridges In DNA, there are, A) 5 bases known as adenine, guanine, thymine, tryptophan and cytosineB) 4 bases known as adenine, guanine, thymine and cystosine C) 4 bases known as adenine, guanine, uridine and cytosine D) 2 bases known as adenine and cytosine E) 3 bases known as adenine, uridine, and cytosine >>>>4 bases known as adenine, guanine, thymine, and cytosine One turn of an alpha helix represents ___ amino acid residues A) 2.6 B) 3 C) 3.6 D) 4 E) none of the above >>>>C) 3.6 The second law of thermodynamics states A) The entropy of a system plus surroundings is unchanged by irreversible processes B) Systems tend to proceed from disordered to more ordered states C) Naturally occuring processes proceed to a state of minimum PE D) The entropy of a system plus surroundings is always changed by reversible processes E) Entropy is equal to the heat capacity at constant pressure >>>>D The 4 atoms that comprise more that 99% of atoms in the body are A) H, C, O, N B) C, O, P, S C) N, O, Ca, Fe D) C, H, Na, K >>>>H, C, O, N Which of the following amino acids lacks an assymetric Ca carbon atom? A) Serine B) Glycine C) Histidine D) Glutamine E) Leucine >>>>Glycine A five carbon sugar lacking a hydoxyl at the 2' carbon is found in A) DNA B) RNA C) rRNA D) mRNA E) tRNA >>>>DNA Which of the following statements about the beta-pleated sheet is false A) adjacent chains of amino acids that form beta sheets always run in the same direction B) They arise due to cooperative formation of H bondsC) The hydrogen bonds in this structure are essentially interstrand rather than intrastrand D) The peptide backbone in the beta sheet is in its most extended conformation E) The side chain in the pleated beta sheet >>>>A A van't Hoff plot is used to A) determine volume change fora reaction B) Determine enthalpy change for a rxn C) determine the free energy change for a rxn D) determine the equilibrium change for a rxn E) determine the pressure change >>>>enthalpy change For a spontaneous rxn: A) H must be negative B) G must be negative C) S must be negative D) T must be negative E) G must be positive >>>>G must be negative If the pH of a solution is 7, molar concentration of hydrogen ions is A) 10^14 B) 10^-14 C) 10^7 D) 10^-7 E) None of the above >>>>10^-7 The constant Kw, the ion product of water at 25 C, can be written as A) Keq=10^14=[H+][OH-] B) Keq=10^-14=[H+][OH-] C) Keq=10^-12=[H+][OH-] D) Keq=10^-7=[H+][OH-] E) None of the above >>>>Keq=10^-14=[H+][OH-] A nucleotide consists of A) a sugar, base, and phosphate B) a sugar and a phosphate C) a base and a phosphate D) any two paired bases E) a sugar, base, and glycine >>>>A sugar, base and phosphate A buffer of HPO42-/H2PO4- has a pH of 7.4. What is the ratio of HPO2-/H2PO4- in this buffer? The pK of the couple is 7.2. A) 2.6 B) .62 C) 2 x 10^-3 D) 7E) 1 x 10^-14 >>>>1.6 Phosphoric Acid, H3PO4: A) is a polyprotic acid B) requires 4 equivalents of OH- to neutralize it C) Is a strong acid D) is a strong conjugate base of an acid E) All of the above >>>>Is a polyprotic acid At neutral pH A) Acidic amino acids have a net positive charge B) Basic amino acids have a net positive charge C) Acidic amino acids have no charge D) basic amino acids have no charge E) None >>>>Basic amino acids have a net positive charge Which of the following sets of amino acid residues would you most likely find on the exterior surface of a globular protein at physiological pH? A) Phe, Asn, Glu, Trp B) Ala, Phe, Asp, Glu C) Thr, Met, Glu, Arg, Lys D) Glu, Asp, Arg, Lys, E) Ala, Ile, Val, Leu >>>>D Living Organisms are: A) in eqbm with their surroundings B) at a steady state with their surroundings C) removed from eqbm with their surroundings D) always moving towards disorder >>>>B Dialysis uses semipermeable membranes that: A) Allows small molecules and water to pass but not proteins B) retains small molecules and water but allows proteins to pass thru C) separates proteins on the basis of their electrical charge D) Separates proteins on the basis of their specific gravity E) Retains small molecules, water, and proteins >>>>A Which of the following best describes the order o [Show More]

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