BIOCHEM ACS STUDY GUIDE LATEST

BIOCHEM ACS STUDY GUIDE LATEST

UPDATED

Each of the following subcellular structures contains DNA EXCEPT

• the nucleus.
• ribosomes.
• chloroplasts.
• mitochondria. - Answer- B

In plant and animal cells, the three-dimensional integrity of the cell is maintained, in part, by an internal network of filaments called

• the cell wall.
• the Golgi apparatus.
• the cytoskeleton.
• the endoplasmic reticulum. - Answer- C

Of the following, which are prokaryotes?

• viruses
• bacteria
• yeast
• plant cells - Answer- B

G° for the conversion of glycerol-3-phosphate to glycerol + Pi is -2.2 kcal/mole. Thus, you can conclude that

• this reaction will occur spontaneously.
• this reaction may or may not occur spontaneously, depending on the

actual concentrations of reactants and products.

• this reaction will only occur spontaneously if it is coupled to

another reaction that has a more favorable G°.

• this reaction is so strongly favorable that it could be coupled to

drive an otherwise unfavorable cell reaction. - Answer- B In most biochemical reactions, ∆PV is

• negligible
• positive
• negative
• dependent on ∆E - Answer- A

According to the Second Law of Thermodymnamics, 1 / 3

• the total entropy change in any reaction that occurs spontaneously must be greater

than 0.

• the total entropy change in any reaction that occurs spontaneously must be less

than 0.

• the total entropy of the universe remains constant.
• the total entropy of the universe is always decreasing. - Answer- A

Which of the following is true?

• Liquid and solid water have the same number of hydrogen bonds per molecule of

water

• Liquid water has more hydrogen bonds per molecule than does solid water
• Solid water has more hydrogen bonds per molecule than does liquid water
• Hydrogen bonding is a major factor in the structure of gaseous water
• None is true - Answer- C

What is the pH of an aqueous solution that has a [OH-] of 3.45 x 10-5 M?

A. 3.47

B. 4.47

C. 5.53

D. 9.54

• none of the above - Answer- D

A peptide was found to have a molecular mass of about 650 and upon hydrolysis produced Ala, Cys, Lys, Phe, and Val in a 1:1:1:1:1 ratio. The peptide upon treatment with Sanger's reagent produced DNP-Cys and exposure to carboxypeptidase produced valine. Chymotrypsin treatment of the peptide produced a dipeptide that contained sulfur and has a UV absorbance, and a tripeptide. Exposure of the peptide to trypsin produced a dipeptide and a tripeptide. Deduce the sequence of the peptide.

• Val-Ala-Lys-Phe-Cys
• Cys-Lys-Phe-Ala-Val
• Cys-Ala-Lys-Phe-Val
• Cys-Phe-Lys-Ala-Val
• Val-Phe-Lys-Ala-Cys - Answer- D

Which amino acid has an R-group pKa closest to physiological pH?

• lysine
• histidine
• glutamate
• arginine
• aspartate - Answer- B

Which is true regarding the orientation of the R-groups in beta structures?

• In the parallel beta sheet structures the amino acid R-groups are all on the same

side of the sheet.

• In the antiparallel beta sheet structure the R-groups on alternate strands are on the

same side of the sheet. 2 / 3

• In parallel and antiparallel sheets consecutive R-groups on each peptide strand

alternate sides of the sheet.

• Because of the free rotation around the alpha carbon, the R-groups can seek the

least crowded region and are not restricted to specific side of the sheet.

• a and b - Answer- C

A reagent commonly employed to cleave disulfide bonds in proteins is

• 2,4-dinitrofluorobenzene
• urea
• 2-mercaptoethanol
• phenylisothiocyanate
• cyanogen bromide - Answer- C

With respect to a relaxed muscle, which of the following is true?

• the number of actin-myosin cross-bridges is maximized and the muscle is shortened
• the number of actin-myosin cross bridges is maximized and the muscle is stretched
• the number of actin-myosin cross bridges is minimized and the muscle is shortened
• the number of actin-myosin cross bridges is minimized and the muscle is stretched
• none of the above - Answer- D

Which of the following does not describe hemoglobin?

• Hemoglobin is an oxygen transport protein.
• Hemoglobin is an allosteric protein.
• Hemoglobin has quaternary structure.
• Copper ions are important in hemoglobin's ability to bind oxygen.
• Hemoglobin is composed, in part, of an iron containing heme group. - Answer- D

Which of the following would allow you to determine the isoelectric point of a protein?

• protein quaternary structure
• protein solubility as a function of pH
• protein size
• protein shape
• protein tertiary structure - Answer- B

A mixture of urease (pI = 5.1, mol. wt. 482,700), catalase (pI = 5.6 mol. wt. 247,500), lactoglobin (pI 5.2, mol. wt. 37,100) and hemoglobin (pI 6.9, mol. wt. 64,500) were applied in a pH 6.5 buffer to a DEAE-cellulose chromatography column and eluted with the same buffer.What was their order of elution?

• urease, lactoglobin, catalase, hemoglobin
• hemoglobin, catalase, lactoglobin, urease
• urease, catalase, hemoglobin, lactoglobin
• lactoglobin, hemoglobin, catalase, urease
• cannot be determined from the information given - Answer- B
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