单项选择题X 纠错
A．Is complementary to mRNA.
B．Forms double-stranded RNA.
C．Joins with the 30S subunit.
D．Inhibits protein synthesis.
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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)
单项选择题
A．Protein kinase A
B．Phosphorylase kinase
C．Glycogen phosphorylase
D．Protein phosphatase
E． Protein phosphatase inhibitor-1
单项选择题
A．25-50% of the pre-rRNA is degraded
B． Pre-rRNA binds to ribosomal protein
C． Pre-rRNA is cut to form three classes of rRNA
D．Pre-rRNA is methylated
E．The rRNA gene for the 40S subunit is transcribed separately
