exam 1 bch 3051

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FORM A BCH 3053 Introductory Biochemistry Spring, 2014 Exam 1, January 31 Choose the best answer from the multiple choices. Question #21 is Extra Credit pH= pK a +log [ conjugate base ] [ Conjugate acid ] pH=−log ¿¿ ∆G=HT∆S

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Page 1: Exam 1 BCH 3051

FORM ABCH 3053 Introductory Biochemistry Spring, 2014

Exam 1, January 31

Choose the best answer from the multiple choices.

Question #21 is Extra Credit

pH=pKa+ log[conjugatebase ][Conjugate acid ]

pH=−log¿¿

∆G=H−T ∆S

Page 2: Exam 1 BCH 3051

FORM A

Page 3: Exam 1 BCH 3051

Figure 1

FORM A1. A spontaneous reaction is:

a. Exergonicb. Endergonicc. At equilibriumd. Always rapide. Always accompanied by a negative enthalpy

2. Which of the following processes results in a decrease on entropy?a. A liquid is volatilizedb. An ice cube meltsc. Water freezesd. Urea dissolves in watere. This reaction occurs: CaCO3(s) →CaO(s)+CO2(g)

3. What is the pH of an acetic acid solution where the concentration of acetic acid is 2mM and concentration of sodium acetate is 10mM. The pKa of acetic acid is 4.76.

a. 3.07b. 5.46c. 4.06d. 6.21e. 3.76

4. Pick the correct conjugate acid for the conjugate bases shown below in bold:

Bases

(HO CH2)3C-NH2 H3C-CHOH-COO- NH3 Na2HPO4+H3N-CH2-COO-

a. (HO CH2)3C-NH4+ H3C-CHOH-COO2- There is none NaH2PO4

+H3N-CH2-COOH

b. ((H2+) O CH2)3C-NH4+ H3C-CHOH-COOH NH2

- NaH3PO4 H3N-CH2-COO-

c. (HO CH2)3C-NH4+ H4

+ C-CHOH-COO- There is none NaH3PO4

+H4N-CH2-COOH

d. (HO CH2)3C-NH- H3C-CHOH-COO2- NH3+ H3PO4 H2N-CH2-COO-

e. (HO CH2)3C-NH3+ H3C-CHOH-COOH NH4

+ NaH2PO4+H3N-CH2-COOH

5. Refer to figure 1. Which of the groups could not act as a proton acceptor in a hydrogen bond

a. Ib. IIc. IIId. IVe. All can accept a hydrogen in a hydrogen bond

BOTH ANSWERS WILL BE CORRECT

Page 4: Exam 1 BCH 3051

FORM A6. An HCl solution has a pH=3. If you dilute 10mL of the solution to 1000mL, the final pH will be

a. 1.0b. 2.0c. The pH does not changed. 4.0e. 5.0

7. Calculate the final pH of a solution made by the addition of 10 mL of a 0.5 M NaOH solution to 500 mL of a weak acid, HA. The concentration of the conjugate acid is 0.2M, the pH is 5.00 and the pKa = 5.00. Neglect the change in volume

a. 6.10b. 5.04c. 7.00d. 5.99e. 6.91

8. Which of the following statements about hydrogen bonds is false? a. The donor is a hydrogen atom bonded to a less electronegative atom than hydrogen.b. The more linear the bond, the stronger the attraction.c. The acceptor must contain a non-bonded pair of electrons.d. They are a type of covalent bonde. They are the result of dispersion forces

BOTH ANSWERS WILL BE CORRECT

9. What is the net charge of the following peptide at pH 1.00?Cys-Ala-Gly-Arg-Gln-Met

a. +1b. +2c. -1d. 0e. -2

10. Given the R-groups in the peptide, ALA-GLN-ARG-SER-HIS, it would likely be:a. Very water solubleb. Somewhat water solublec. Not very water solubled. Not soluble at alle. You cannot tell from the sequence

11. Which amino acid would migrate furthest toward the anode during electrophorese?a. Aspartic acidb. Argininec. Tyrosined. Histidinee. Glutamine

Page 5: Exam 1 BCH 3051

FORM A

12. What is the isoelectric point of tyrosine?a. 2.20b. 5.65c. 9.11d. 10.07e. 7.13

13. Which of the following amino acids has a net charge of +1 at pH 4 and a net charge of 0 at pH 8?a. Glub. Argc. Hisd. Tyre. Two of the above

14. What is the ratio of conjugate base to conjugate acid in Asp at pH = 5.2?a. 7.6b. 0.02c. 12.3d. 6.72e. 35.48

15. Which of the following forces are involved in maintaining the primary structure of a protein?a. Covalent bondsb. Hydrogen bondsc. Ionic interactionsd. Hydrophobic interactionse. Dipole-dipole interactions

Use figure 2 to answer the questions below

Figure 2

Page 6: Exam 1 BCH 3051

FORM A

16. The type of bonding labeled “L” in figure 2 is: EVERYONE CREDITEDa. Hydrogen bonding of the peptide backboneb. Hydrogen bonding involving the R-groupsc. Hydrophobic interactionsd. Metal ion coordinatione. Electrostatic attraction

17. The type of bonding labeled “M” in figure 2 is:a. Hydrogen bonding of the peptide backboneb. Hydrogen bonding involving the R-groupsc. Hydrophobic interactionsd. Metal ion coordinatione. Electrostatic attraction

18. The type of bonding labeled “O” in figure 2 is:a. Hydrogen bonding of the peptide backboneb. Covalent bonding involving the R-groupsc. Hydrophobic interactionsd. Metal ion coordinatione. Electrostatic attraction

19. Quaternary structure is associated witha. The overall shape of the polypeptide chainb. The sum of secondary and tertiary interactionsc. Simple proteins with only one subunitd. The sequence of amino acidse. The relative orientation of one polypeptide to another polypeptide in a multisubunit

protein

20. Which of the following statements regarding hemoglobin (Hb) and myoglobin (Mb) is true?a. Mb transports oxygen while Hb stores it.b. Mb has quaternary structure but Hb does not.c. Mb displays simple kinetics of binding while Hb displays cooperativity.d. Mb exhibits allosteric control, whereas Hb does not.e. None of the above

21. In allosteric interactionsa. Proteins that consist of a single polypeptide chain form aggregates.b. Disulfide bonds are broken.c. When a small molecule binds to one site of a protein it causes changes at a distant site.d. Metal ions always bind to the protein.e. The sequence of amino acids is altered.