3. Five students are discussing carbohydrate.

 Student A says: Glc(1α B1 )Fru is sucrose.

 Student B says: An aldohexose has 16 stereoisomers.

 Student C says: Hyaluronate and heparin are sulfated heteropolysaccharides. 

Student D says: The α and β anomers of D-glucose can freely interconvert in aqueous solution without breaking any bonds.

 Student E says: α -GalNAc is added to the side-chain of asparagine in N-linked glycosylation. How many students are correct?
(A) 1
(B) 2
(C)3
(D) 4
(E) 5

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1. Which of the following amino acid is branched at β-carbon? (A) Leucine (B) Threonine (C) Serine (D) Phenylalanine (E) Histidine

2. Eric uses a computer software to simulate a 20-residue peptide in different structures. Structure A is an α-helix structure; structure B is a β-strand; structure C is a helix in the collagen structure. The length of these structures should be: (A)C＞B＞A (B) C＞A＞B (C) B＞A＞C (D) A＞B＞C (E) B＞C＞A

4. Five students are discussing hexose structure. Student A says: D-glucose and b-glucosamine are different on C2. Student B says: D-glucose and L-glucose are different on C5. Student C says: D-glucose and D-glucuronic acid are different on C6. Student D says: a-D-glucose and B-D-glucose are different on Cl. Student E says: D-glucose and b-galactose are different on C4. How many students are correct? (A) 1 (B) 2 (C)3 (D) 4 (E) 5

5. Both water and glucose share an–OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is that: (A) the larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis. (B) glucose has more –OH groups per molecule than does water. (C) the–OH group of water is attached to an inhibitory H atom, while the glucose –OH group is attached to C. (D) water and the second substrate, ATP, compete for the active site resulting in a competitive inhibition of the enzyme. (E) water normally will not reach the active site because it is hydrophobic.

6. All of the following are characteristics of hemoglobin's binding of oxygen except: (A) CO2 promotes dissociation of O2 from hemoglobin by lowering the pH. (B) 2,3-Bisphosphoglycerate and O2 are mutually exclusive allosteric effectors of hemoglobin. (C) 2,3-Bisphosphoglycerate promotes release of O2 by hemoglobin. (D) CO2 can bind with hemoglobin's free amino groups and stabilize deoxy-hemoglobin. (E) Protons promote binding of oxygen by hemoglobin.

7. Which of the following is the major advantage of a multi-enzyme complex? (A) It's large size enables it to span an entire membrane. (B) The product of one enzyme is passed directly to the next enzyme without the possibility of difiusion. (C) Multi-enzyme complexes are much less likely to be inhibited. (D) All of the above. (E) None of the above.

8. Glycogen phosphorylase displays allosteric activation and inhibition by multiple modes. Which of the following is a correct relation? (A) Phosphate: positive heterotropic effector. (B) AMP: negative heterotropic effector. (C) ATP: positive heterotropic effector. (D) Glucose-6-phosphate: negative heterotropic effector. (E) Phosphorylation: covalent inhibitor.

9. All are characteristics of molecular motors or motor proteins except: (A) They must be able to associate and dissociate reversibly with a polymeric protein array, a surface or substructure in the cell. (B) They use chemical energy (e.g., ATP) to orchestrate movement. (C) They transfer ATP energy into mechanical energy. (D) ATP bydrolysis is presumed to drive and control protein conformational changes that result in sliding or walking movement of one molecule relative to another. (E) All are true.