Question

14. Which of the following statements is true of lipids? A) Many contain fatty acids in ester or amide linkage. B) Most are simply polymers of isoprene C) Testosterone is an important sphingolipid found in myelin. D) They are more soluble in water than in chloroform. E) They play only passive roles as energy-storage molecules. 15. The sigma factor of E. coli RNA polymerase: A) associates with the promoter before binding core enzyme. B) combines with the core enzyme to confer specific binding to a promoter. C) is inseparable from the core enzyme. D) is required for termination of an RNA chain. E) will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme 16. The excision (splicing) of many group I introns requires, in addition to the primary transcript RNA: A) a cytosine nucleoside or nucleotide and a protein enzyme. B) a guanine nucleoside or nucleotide (only). c) a protein enzyme only. D) a small nuclear RNA and a protein enzyme. E) ATP, NAD, and a protein enzyme. 17. The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is Mr 50,000 and the average lipid is 750.) A) 1 B) 50 C) 200 D) 10,000 E) 50,000 18. Which of the following statements about the polymerase chain reaction (PCR) is false? A) DNA amplified by PCR can be cloned. B) DNA amplification is linear in magnitude. C) Newly synthesized DNA must be heat-denatured before the next round of DNA synthesis begins D) The boundaries of the amplified DNA segment are determined by the synthetic oligonucleotides used to prime DNA synthesis E) The technique is sufficiently sensitive that DNA sequences can be amplified from a single animal or human hair. 19. Facilitated diffusion through a biological membrane is: A) driven by a difference of solute concentration B) driven by ATP C) endergonic. D) generally irreversible. E) not specific with respect to the substrate

Answer 1

14. E - They play only passive roles as energy storage molecules

15.B- Combines with the core enzyme to confer specific binding to a promoter

16.B- A guanine nucleoside or nucleotide (only)

17.

18.B- DNA amplification is linear in magnitude

19.A- Driven by a difference of solute concentration