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BBL Midterm Exam Questions And
Verified Answers
All amino acids are formed by the amination of A. Sugars B. Keto acids C. Short-chain fatty acids D. Esters - Answer B The major metabolic source of amino acid precursors is A. Glycolysis B. Gluconeogensis C. TCA Cycle D. Pentose phosphate pathway - Answer C Which amino acid is formed on a t-RNA? A. Tryptophan B. Selenocysteine C. Methionine D. Alanine - Answer B All amino acids have an R group. What is the significance of the R? A. Each of the 21 amino acids has a unique R group B. Proline and glycine are the only amino acids without an R group C. All R groups have charge D. Not all R groups are bound to the alpha carbon - Answer A At neutral pH, all amino acids are A. Zwitterionic, with both the amine and carboxylic acids charged B. Protonated at the amine group C. Uncharged, and non-reactive
D. Deprotonated at the carboxylic acid - Answer A Of the following amino acids, whose R group has charge? A. Leucine, valine, tryptophan B. Arginine, glycine, isoleucine C. Methionine, cysteine, alanine D. Arginine, lysine, glutamate - Answer D Which of the following amino acids does not have chirality? A. Alanine B. Cysteine C. Glycine D. Proline - Answer C Which are branched chain amino acids? A. Methionine, cysteine, alanine B. Tyrosine, tryptophan, phenylalanine C. Serine, glycine, threonine D. Isoleucine, leucine, valine - Answer D Which amino acids' R groups are basic? A. Aspartate and glutamate B. Lysine, arginine and histidine C. Isoleucine, leucine and valine D. Cysteine, methionine and selenocysteine - Answer B Which amino acids have aromatic R groups? A. Phenylalanine, tryptophan and tyrosine B. Arginine, histidine and lysine C. Alanine, glycine and proline D. Serine, threonine and tyrosine - Answer A The major use of methionine is in
D. Both amine and carboxylic acids are charged and the amino acid has zero net charge
- Answer D Alanine has a pK1 and a pK2 while lysine has a pK1, pK2 and a pKR. Why? A. The R group of alanine is acidic B. The R group of lysine is neutral C. The R group of alanine is non-polar while lysine has a charged R group D. Both alanine and lysine have neutral R groups - Answer C What amino acids have pKR in the acid range? A. Isoleucine and leucine B. Glutamate and aspartate C. Arginine and lysine D. Asparagine and glutamine - Answer B Of the amino acids in protein, how many do not ionize? A. 10 B. All C. None D. 13 - Answer D Where are the polar amino acids found in protein? A. In the interior of globular protein structure B. On the surface of the globular protein to interact with water C. In the active site of enzymes, binding site of receptors D. Answers B & C - Answer D What is chirality? A. L & D forms of amino acid molecules that are not superimposable B. The charge of the amine and carboxylic acid group C. The relationship between the R group and the alpha carbon D. A property of amino acids typified by glycine - Answer A
Nitrogen enters the anabolic pathways of all amino acids as A. Threonine, serine B. Aspartate, asparagine C. Glycine, serine D. Glutamate, glutamine - Answer D What structural region of the amino acid dictates its chemical properties? A. The R group B. The carboxylic acid group C. The amine group D. Both the carboxylic acid and the amine group - Answer A Based on charge, the largest group of amino acids is A. Polar B. Non-polar C. Acidic D. Basic - Answer B Ornithine condenses with carmayl phosphate to form A. Arginosuccinate B. Arginine C. Citrulline D. Urea - Answer C High levels of desmosine in blood indicate A. High levels of red blood cell destruction B. High clotting time C. High elastase activity D. High levels of elastin in blood - Answer C How does the amine base of the amino acid become a conjugate acid? A. It protonates, gaining a H+
B. Alanine C. Proline D. Serine - Answer C In the peptide chain the R groups A. Are always cis of each other B. Are always trans of each other C. Can be either cis of trans D. Are long stretches of cis, then alternate to trans - Answer B Which of the following is true about a peptide bond A. Because of its resonance the N has a partial positive charge B. Because of its resonance the N has a partial negative charge C. Because of its resonance the N has no charge D. Depends on the pKR for what charge the N has - Answer A Whether a Φ or ψ is favored can be found on a A. RicTic plot B. Linweaver-Burk plot C. Ramachandran plot D. Arrhenius plot - Answer C Which amino acid is considered an alpha helix 'breaker'? A. Serine B. Glycine C. Tryptophan D. Arginine - Answer B Interaction of N-H and C=O of the peptide bond leads to local regular structures such as A. Extended chains B. All secondary structures C. Charged outer surface
D. Alpha helix and beta sheets - Answer D What is present in the core of the long axis of an alpha helix? A. Water molecules B. Carbonyl groups C. Amino groups D. Empty space - Answer D Which pair of amino acids are strong alpha-helix formers? A. Serine and lysine B. Alanine and leucine C. Alanine and cysteine D. Tryptophan and tyrosine - Answer B In beta pleated sheet peptide chains, H bonds between parallel strands are A. Not formed B. Weaker, 1 Kcal/mol C. Stronger, 3 Kcal/mol D. Energetically the same as H bonds in anti-parallel strands - Answer B What is the orientation of the R groups of amino acids in beta sheets? A. Perpendicular to the axis and trans to each other B. Perpendicular to the axis and cis to each other C. Lateral to the axis and trans to each other D. Lateral to the axis and cis to each other - Answer A What amino acids are most commonly present in beta turns? A. Proline and glycine B. Serine and glycine C. Serine and threonine D. Proline and serine - Answer A The beta turn is composed of four amino acid residues. Where does the H bond form in
D. HV region shows great variation in amino acid sequence forming stronger binding sites for binding antigen - Answer D If two proteins share a secondary a structural motif, then it can be assumed A. They have similar function B. Nothing in regards to their secondary structural similarities C. These are functionally identical regions D. They belong to the same family of proteins - Answer B What can be said about the enthalpy and entropy of a properly folded protein? A. Entropy decreases as enthalpy increases B. Both entropy and enthalpy decrease C. As enthalpy decease entropy stays the same D. Neither enthalpy nor entropy are affected - Answer B Transporters belong to three distinct families depending on the direction of the substance transported are: A. Anyporter, antiporter and retroporter B. Retroporter, symporter, antiporter C. Forwardporter, backporter, dualporter D. Uniporter, symporter, antiporter - Answer D In the human body, muscles move due to A. The interaction of actin and myosin proteins B. The interaction of immunoglobulin and fibronectin C. The interactions of the three strands of collagen D. Answers A and C - Answer A In signal transduction pathways, a chemical message binds to the receptor and it causes a cytosolic G protein bound to the receptor to A. Bind to the enzyme protein kinase A and activate binding to target proteins
B. Bind to protein kinase A and produce cAMP from ATP C. Bind to adenylate cyclase and produce cAMP from ATP D. Activate the release of calcium ions - Answer C How does hemoglobin (Hb) differ from myoglobin (Mb)? A. Mb has a lower affinity for O B. Hb has Fe3+ while Mb has Fe2+ C. Hb has quaternary structure, Mb has tertiary structure D. Both Hb and Mb carry O2 in blood - Answer C Which functional groups on the first and second amino acid form the peptide bond? A. They are randomly assembled B. The peptide bonds are formed by the R groups of the first and second amino acids C. The amine group of the first and the carboxylic acid of the second D. The carboxylic acid of the first and the amine group of the second - Answer D Peptide bonds are formed and broken by the reverse processes dehydration synthesis and hydrolysis. What is being taken away or added back in these reactions? A. R groups are added or removed B. The amine and carboxylic acid groups are added or removed C. Water molecules are added or removed D. Protons are added or removed - Answer C Where are the Φ and ψ angles of rotation found on the amino acid in a peptide chain? A. Between the R group and the alpha carbon B. Between the amine N and the C of the carbonyl group of the peptide bond C. Between the N and alpha C bond, and the bond between the carbonyl carbon bond to the alpha C. D. Between the alpha carbon and the N of the amine group - Answer C What are the strongest bonds holding a peptide into tertiary structure? A. Hydrophobic effect
D. Their effectiveness as catalysts is independent of temperature - Answer B Substrate binds to the active site through A. Ionic bonds B. Covalent bonds C. Non-covalent interactions D. Hydrophobic interactions - Answer C the binding energy of the enzyme for the substrate A. Raises the energy needed for the reaction to occur B. Has no effect on the reaction of substrate to form product C. Lowers the energy requirement for the reaction to occur D. It helps the substrate bind to the active site, but then is lost from the complex of substrate and enzyme - Answer C During a catalyzed reaction, which energy is the lowest? A. ΔH of the formation B. ΔE of the activation C. ΔG of the free energy D. Total ΔH - Answer B When ΔG is negative, which of the following is true? A. The reaction is non-spontaneous and Keq= B. The reaction is non-spontaneous and Keq= C. The reaction is spontaneous and Keq<< D. The reaction is spontaneous and Keq>>1 - Answer D During an exergonic reaction A. the energy of the product is always greater than the substrate B. the energy of the product is always the same as the substrate C. the energy of the product is always less than the substrate D. it depends on the reaction - Answer C
In an endothermic reaction, which of the following are true? A. ΔH of the reaction is positive and the product has less energy than the reactants B. ΔH=0 and the energy of the reactants and products are the same conserving energy C. ΔH of the reaction is positive and the energy of the product is greater than the reactant D. ΔH of the reaction is negative and the energy of the product is less than the reactant - Answer C What is the function of co-enzymes? A. They are part of the reaction along with the substrate and aid the active site forming the transition molecule B. They stabilize the enzyme structure C. They bind to the substrate to aid binding to the active site D. They aid the enzyme stabilizing the product - Answer A Why is the reaction that takes place in the hexokinase active site an example of induced fit. A. Because hexokinase only binds glucose B. Because hexokinase binds several 6 carbon sugars C. Because hexokinase only binds straight chains D. Because hexokinase binds both organic and inorganic residues - Answer B Hexokinase phosphorylates numerous 6-carbon hexose sugars, but the reaction is linked to the hydrolysis of ATP and requires Mg2+. Which statement describes this reaction accurately? A. The hydrolysis of ATP is exothermic and has a negative ΔG and drives the phosphorylation of the hexose sugar, and the Mg2+ binds the phosphate group being added to the hexose B. The hydrolysis of ATP is endothermic and the Mg2+ binds to the protein to the change it shapes C. The role of the Mg2+ is to stop water from inferring with the reaction and ATP binds to
B. The concentration of transition state formed C. The energy need to form the transition state D. The concentration of product formed - Answer A In metallo-catalysis, the metal is found A. Bound to the substrate B. Transient in the active site C. Covalently bound to the protein D. Bound to the co-enzyme - Answer C Which kinetic value is experimentally determined? A. Km B. Kcat C. Turnover number D. Vmax - Answer D
The ratio Kcat/Km is A. Represents the affinity of the enzyme for substrate B. Determines how tightly enzyme binds substrate C. The constant that measures catalytic efficiency D. The rate of transition state formation - Answer C
Competitive inhibition affects which kinetic value? A. The ratio Kcat/Km B. Kcat C. Vmax D. Km - Answer D
A Hill plot
A. is used to show inhibition B. is another way of determining Vmax and Km C. is used to determine the Kcat D. shows co-operativity in binding of substrate - Answer D
Why does the substrate bind to the active site? A. Since no covalent bonds are formed, the substrate is not bound to the active site B. Because specific amino acid R groups form non-covalent interactions with the substrate C. Because specific amino acid R groups bind covalently with the substrate D. Because in the active site the substrate is bound by both covalent and non-covalent bonds - Answer B
In the serine protease active site, which amino acids form the catalytic triad? A. Histidine, aspartate, glycine B. Glycine, serine, threonine C. Seine, proline, arginine D. Histidine, aspartate, serine - Answer D
How does a catalyst help a chemical reaction that is unfavorable to occur? A. The chemical reaction is always possible even without a catalyst B. The catalyst speeds up the reaction C. By acting only in reactions that don't require external energy D. The catalyst helps overcome the entropy barrier of the reaction - Answer D
An electrophile is A. A positively charged, electron rich atom B. A negatively charged, electron rich atom
D. Lactose - Answer AD
What is the molecular formula for glucose? A. CH3OH B. C6H12O C. C12H22O D. C6H12O5 - Answer B
Which of the following molecules is a carbohydrate? A. C3H7O2N B. C13H26O C. C6H12O D. C6H12O12 - Answer C
Which of the following is not considered a polysaccharide? A. starch B. glycogen C. maltose D. cellulose - Answer C
How many stereoisomers are possible for an aldopentose such as ribose? A. 2 B. 4 C. 8 D. 16 - Answer C
How many stereoisomers are possible for a ketopentose such as ribulose?
A. 2
B. 4
C. 8
D. 16 - Answer B
Which of the following characterizes an asymmetric carbon? A. It has four identical groups attached to it B. It has four different groups attached to it C. It has at least one carboxyl and one amino group attached to it D. It has two heavy groups on one side and two light groups on the other - Answer B
To possess optical activity, a chemical compound must be A. a hexose B. aromatic C. symmetric D. asymmetric - Answer D
At eq in sln, d-glucose consists of a mix of its anomers. What most accurately describes the sln? A. The solution consists of approximately equal amounts of the alpha- and beta-anomers B. The straight-chain form is present in high concentration C. The alpha-anomer is more stable and is slightly preferred over the b-anomer D. The beta-anomer predominates over the alpha-anomer by a ratio of approximately 2:
The transformation of a monosaccharide into its isomer _________ occurs easily and does not require the assistance of a catalyst. - Answer anomer
