Which description is wrong about RNA? ( )
A. mRNA contains codon
B. There are three main classes of RNA molecules, mRNA,tRNA and rRNA
C. The rRNA is a component of ribosomes
D. RNA with the maximum molecular weight is tRNA
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Most eukaryotic mRNA 3′ terminus is ( ) A.poly
A. D.poly
B. C.poly
C. B.poly
The ultraviolet absorption of nucleic acid with maximum at about ( )
A. 280nm
B. 220nm
C. 260nm
D. 340nm
Which one is true about the active center of the enzyme? ( )
A. the portion that only combines with the substrate
B. the portion that combines with substrate but does not exert the catalysis
C. the portion that only catalyzes the substrate to the product
D. the region for binding substrates and catalyzing substrates to products
Which compound provide nitrogen for N3 and N9of purine ring ? ( )
A. Gln
B. Gly
C. Ala
D. Asp
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