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单项选择题
A．酶与底物共价结合的活性位点；
B．酶与底物非共价结合的活性位点；
C．对于一个与蛋白质以共价形式相作用的小分子的普遍称呼；
D．对于一个与蛋白质以非共价形式相作用的小分子的普遍称呼；
E．一个缺乏酶活性的球蛋白
单项选择题
A．Develop normally.( )
B．Stop cell division.
C．Have abnormal cell migration(迁移).
D．Don't exhibit action potentials.
单项选择题
A．Is complementary to mRNA.
B．Forms double-stranded RNA.
C．Joins with the 30S subunit.
D．Inhibits protein synthesis.
单项选择题
A．The genes are located outside the nucleolus(核仁).
B．The genes are transcribed by RNA polymerase III.
C．The promoter region of the 5S rRNA gene is internal to the gene.
D． all of the above
单项选择题
A．One copy of each ribosomal transcription unit.
B．Thousands of copies of the 5S rRNA gene.
C．Two copies of each gene for rRNA and ribosomal proteins.
D．Two copies of each gene for rRNA and one copy of each ribosomal proteingene.
单项选择题
A．Transmission(透射) electron microscope
B．Scanning electron microscope
C．Differential centrifugatioin(差速离心)
D．X-ray crystallography
单项选择题
A． Water leaves the cell by osmosis.
B． C1- is diffusing through transmembrane channels.
C． C1- diffusion is aided by a mobile carrier.
D．An active transport symport transports C1-/H+.
E．None of the above
单项选择题
A．Stomach(胃) and kidneys
B．Smooth muscle
C．Heart muscle
D．Intestinal epithelial tissue(肠表皮组织)
