4. Which of the following does not apply to the construction or use of a DNA library?
(A) Determining the location of a particular DNA sequence in a DNA library requires a suitable hybridization probe.
(B) Genomic libraries are better for expressing gene products than cDNA libraries.
(C) Many segments of DNA from a cellular genome are cloned.
(D) Specialized DNA libraries can be made by cloning DNA copies of mRNAs.
(E) The DNA copies of mRNA found in a cDNA library are made by reverse transcriptase.

80. Which of the following metal ions in heme can bind oxygen reversibly? (A) Fe2+ (B) Mg2+ (C) Ca2+ (D) None of above

1. To possess optical activity, a compound must be: (A) a carbokydrate. (B) a hexose. (C) asymmetric. (D) colored. (E) D-glucose.

2. A major component of RNA but not of DNA is: (A) adenine. (B) cytosine. (C) guanine. (D) thymine. (E) uracil.

3. In the Watson-Crick model for the DNA double helix (B form), the A-T and G-C base pairs share which one of the following properties? (A) The distance between the two glycosidic (base-sugar) bonds is the same in both base pairs, within a few tenths of an angstrom. (B) The molecular weights of the two base pairs are identical. (C) The number of hydrogen bonds formed between the two bases of the base pair is the same. (D) The plane of neither base pair is perpendicular to the axis of the helix. (E) The proton-binding groups in both base pairs are in their charged or ionized form.

5.Which vitamin is derived from cholesterol? (A) A (B) B12 (C) D (D) E (E) K

6. The shortest o helix segment in a protein that will span a membrane bilayer has about_____amino acid residues. (A) 5 (B) 20 (C) 50 (D) 100 (E) 200

7. Which of the following statements concerning receptor enzymes is correct? (A) They are not usually membrane-associated proteins. (B) They contain an enzyme activity that acts upon a cytosolic substrate. (C) They contain an enzyme activity that acts upon the extracellular ligand. (D) They have a ligand-binding site on the cytosolic side of the membrane. (E) They have an active site on the extracellular side of the membrane

8. Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of: (A) aerobic metabolism. (B) anabolic metabolism. (C) a net reductive process. (D) fermentation. (E) oxidative phosphorylation.

9. Which one of the following enzymatic activities would be decreased by thiamine deficiency? (A) Fumarase (B) Isocitrate dehydrogenase (C) Malate dehydrogenase (D) Succinate dehydrogenase (E) a-Ketoglutarate debydrogenase complex

10. Which of these is able to cross the inner mitochondrial membrane? (A) Acetyl-CoA (B) Fatty acyl-carnitine (C) Fatty acyl-CoA (D) Malonyl-CoA (E) None of the above can cross.