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【单选题】
正拍起拍中,预示拍是拍?A.
唱的当拍
B.
唱的前一拍
C.
唱的后一拍
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皮皮学刷刷变学霸
举一反三
【简答题】当今的世界三大饮料包括（ ）。A. 可乐B. 可可C. 咖啡D. 茶叶E. 奶茶
【多选题】How are purine and pyrimidine bases recycled by salvage pathways?
A.
Free purine and pyrimidine bases are constantly released in cells during the metabolic degradation of nucleotides. Free purines are in large part salvaged and reused to make nucleotides, in a pathway much simpler than the de novo synthesis of purine nucleotides described earlier.
B.
One of the primary salvage pathways consists of a single reaction catalyzed by adenosine phosphoribosyltransferase, in which free adenine reacts with PRPP to yield the corresponding adenine nucleotide.
C.
Free guanine and hypoxanthine (the deamination product of adenine ) are salvaged in the same way by hypoxanthine-guanine phosphoribosyltransferase.
D.
A similar salvage pathway exists for pyrimidine bases in microorganisms, and possibly in mammals.
【简答题】A．points B．stations C．establishments D．bases
【简答题】A．ends B．backgrounds C．origins D．bases
【简答题】A．points B．stations C．establishments D．bases
【单选题】Which of the following statements about minor bases is wrong?
A.
In DNA, the most common minor bases are acetylated forms of the major bases.
B.
In some viral DNAs, certain bases may be hydroxymethylated or glucosylated.
C.
Altered or unusual bases in DNA molecules often have roles in regulating or protecting the genetic information.
D.
Minor bases of many types are also found in RNAs, especially in tRNAs.
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