2. Which of the following statements regarding cytoskeleton is correct?

(1) The plasma membrane of eukaryotic cells is supported by microtubules. 

(2) Within an actin filament, each actin subunit is surrounded by 4 neighboring actin subunits. (3) In cells, the y-tubulin ring complex is found at the microtubule (+) end.
(A) (1)
(B) (2)
(C) (3)
(D) (1) and (2)
(E) (2) and (3)

38. What statement of mitochondrion is INCORRECT? (A) Mitochondrial DNA is circular (B) A double-membrane-bound organelle (C) Mitochondrial DNA is inherited from mother (D) ATP is produced by oxidizing pyruvate and NADH in mitochondria (E) One mitochondrion only contains one copy of its DNA

39. G protein-coupled receptors (GPCRs) have ________ transmembrane-domains. When the GPCR binds to a ligand, it activates an associated G protein by exchanging the ________ bound to the G protein for a ________. (A) Seven, GTP, GDP (B) Five, GTP, GDP (C) Seven, GDP, GTP (D) Five, GDP, GTP (E) Three, GTP, GDP

40. Which of the following is not involved in RNA splicing? (A)UI RNA (B) Small nuclear ribonucleoproteins (C) Ribozyme (D) Transesterification (E) Nonsense-mediated mRNA decay

1. Cytosolic proteins are anchored to the plasma membrane by? (1) prenylation (2) S-nitrosylation (3) farnesylation (4) myristoylation (A) (1), (2) or (3) (B) (1), (2) or (4) (C) (1) (3) or (4) (D) (2), (3) or (4) (E) (1), (2), (3) or (4)

3. Which of the following is a common intracellular second messenger?(A) adenosine triphosphate (ATP) (B) guanine monophosphate (cGMP) (C) 1,2 diacylglycerol (DAG) (D) Epinephrine (E) Serotonin

複選題4. Eukaryotic mRNA binding to the ribosomes is facilitated by?(A) Kozak consensus sequence (B) the Shine Dalgarno sequence (C) the 7-methyl guanosine cap (D) poly A tail (E) All of above facilitate mRNA binding to the ribosomes.

5. The resting membrane potential in animal cells depends largely on what channel?(A) nongated H⁺ (B) gated Na⁺ (C) nongated Na⁺ (D) gated K⁺ (E) nongated K⁺

6. Which of the following statements regarding aquaporins is correct? (1) Aquaporins are water-channel proteins. (2) Aquaporins specifically increase the permeability of biomembranes to water- soluble salts. (3) The level of aquaporin 2 is rate-limiting for water transport by the kidney and is essential for resorption of water in the kidney. (A) (1) and (2) (B) (1) and (3) (C) (2) and (3) (D) All of above are correct (E) None of above is correct

7. Which of the following statements regarding restriction enzymes is correct? (1) Restriction enzymes are named for the bacterium they are derived from. (2) Restriction enzymes protect bacteria from viral infection. (3) In order to insert a foreign gene into a plasmid, both must be cut by the same restriction enzyme. (A) (1) and (2) (B) (1) and (3) (C) (2) and (3) (D) None is correct (E) All is correct

8. Which of the following statements regarding a gene expression vector in E. coli is correct? (1) always contains an origin of replication. (2) usually contains a gene that confers antibiotic resistance to the bacterial host. (3) always contains DNA segments for the regulation of mRNA production. (A) (1) and (2) (B) (1) and (3) (C) (2) and (3) (D) None is correct (E) All is correct