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BCH FINAL EXAM SET QUESTIONS WITH CORRECT ANSWERS
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BCH FINAL EXAM SET QUESTIONS WITH CORRECT ANSWERS
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BCH FINAL EXAM SET QUESTIONSWITH CORRECT ANSWERS
After the following features are common to all living organisms, except: - ANSWER-
cellular structures
identify the functional group(s) in the molecule - ANSWER- amide
Phosphoenolpyruvate donates a phosphate groups to ADP to produce pyruvate and
ATP. The ΔG value for this reaction at 25°C is -63 kJ/mol and the value of ΔS is +190
J/K-mol. What is the value of ΔH? Is the reaction exothermic or endothermic? -
ANSWER- -6.4 kj/mol, exothermic
A given reaction occurs spontaneously, with an exothermic change in enthalpy and an
increase in disorder. Which answer choice below correctly assigns the relative changes
to ΔS, ΔH, and ΔG? - ANSWER- +)ΔS; (-)ΔH; and (-)ΔG
identify the class of basic biomolecules represented by the following structure. -
ANSWER- Amino acids
Which organelle does not contain DNA? - ANSWER- Rough Endoplasmic Reticulum
A reaction will be spontaneous at all temperatures if what two conditions are met? -
ANSWER- a decrease in enthalpy and increase in entropy
If atoms with greatly differing electronegativities form a bond, that bond will be -
ANSWER- polar
The hydrophobic effect, resulting in the exclusion of nonpolar substances from an
aqueous solution is the result of the strong attractive force between the nonpolar
molecules. - ANSWER- false
In a typical hydrogen bond - ANSWER- three atoms lie in a straight line
Which of the following statements about hydrogen bonds is false? - ANSWER- The
donor is a hydrogen atom bonded to a less electronegative atom then hydrogen.
What is the concentration of a lactic acid buffer (pKa 3.9) that contains 0.25 M
CH3CH(OH)COOH and 0.15 M CH3CH(OH)COO-? What is the pH of the buffer? -
ANSWER- 0.40 M; pH 3.68
,Which would be a more effective buffer at pH 8.0? - ANSWER- 0 mM glycinamide (pKa
8.20)
Ionic compounds and polar covalent compounds tend to dissolve in water because of -
ANSWER- ion-dipole and dipole-dipole interactions.
Which of the following would be the strongest acid? - ANSWER- Formic acid, pK 3.13
Formation of hydrogen bonds is fundamental to the assembly of the DNA double helix.
How many potential H-bond donor atoms are present in the nitrogenous base of GTP
below (boxed area only)? - ANSWER- 2
What is the pH of an acetic acid solution where the concentration of acetic acid is 2 mM
and the concentration of sodium acetate is 20 mM? The pKa of acetic acid is 4.76. -
ANSWER- 5.76
Which groups of a pair of amino acids must react to form a peptide bond? - ANSWER-
the carboxyl of one and the amino of the other
Which of the following types of amino acids has uncharged side chains at neutral pH? -
ANSWER- Polar-neutral amino acids
Which of the following is NOT a class of amino acid? - ANSWER- asymmetric
Consider the titration curve below:
Which point would most likely represent the pKa value of the carboxyl group? -
ANSWER- 2
Consider the titration curve below:
Which point(s) would correspond to pK values? - ANSWER- 2 and 4
Which of the following is true about uncommon amino acids? - ANSWER- They are
formed in the protein by post-translational modification of the parent amino acid.
Which of the following statements is true of resonance structures? - ANSWER-
Resonance structures differ from one another only in the positioning of electrons.
Identify the amino acid below and classify it by polarity. - ANSWER- R, polar
Identify the charged groups in the peptide below at pH 1.
Val-Met-Ser-Ile-Phe-Arg-Cys-Tyr-Leu - ANSWER- Val, Arg, Leu
Which amino acid has a pI of 5.0? - ANSWER- C
, The sequence of monomers in any polymer is this type of structure: - ANSWER-
primary structure
Hemoglobin is a heterotetramer that has 4 identical subunits. - ANSWER- False
Which one is not an example of supersecondary structure? - ANSWER- the pyrrole ring
Which of the following amino acid substitutions would be least likely to have a
deleterious effect on protein function? - ANSWER- Leu changes to Ile
In the α helix the hydrogen bonds: - ANSWER- occur mainly between electronegative
atoms of the backbone.
Which of the following is true about sickle cell hemoglobin? - ANSWER- It has a single
amino acid substitution in the beta chain.
What type of covalent bond is responsible for holding together the primary structure of
proteins? - ANSWER- Amide bonds
In hemoglobin, the transition from R state to T state (high to low affinity) is triggered by:
- ANSWER- 2,3-bisphosphoglycerate (BPG) binding
Which of the following best describes what happens when hemoglobin binds
bisphosphoglyceric acid (BPG)? - ANSWER- Binding of BPG is important to the
allosteric nature of hemoglobin.
Which technique involves the determination of protein primary structure by a physically
breaking a peptide into smaller fragments? - ANSWER- Mass spectrometry
Which separates on the basis of molecular weight? - ANSWER- Gel filtration (size
exclusion)
Which of the following techniques is useful in determining the tertiary structure of
peptides? - ANSWER- X-ray crystallography
Which type of column is most affected by the shape of the protein, for example,
comparing spherical and cigar-shaped proteins? - ANSWER- Gel filtration
Which of the following is not an example of column chromatography? - ANSWER-
ammonium sulfate fractionation
A biochemist is attempting to separate a DNA-binding protein (protein X) from other
proteins in a solution. Only three other proteins (A, B, and C) are present. The proteins
have the properties listed in the table below. What type of protein separation technique
might be used to separate protein X from protein A?
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