A．胆固醇可防止膜磷脂氧化；
B．正常细胞恶变过程中，胆固醇/磷脂增加；
C．胆固醇/磷脂下降，细胞电泳迁移率减少；
D．在质膜相变温度以下，增加胆固醇，可以提高膜的流动性

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

A．肌球蛋白纤维
B．角蛋白纤维
C．微丝
D．钙粘着蛋白

A．Develop normally.( )
B．Stop cell division.
C．Have abnormal cell migration(迁移).
D．Don't exhibit action potentials.

A．Is complementary to mRNA.
B．Forms double-stranded RNA.
C．Joins with the 30S subunit.
D．Inhibits protein synthesis.

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

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.

A．Transmission(透射) electron microscope
B．Scanning electron microscope
C．Differential centrifugatioin(差速离心)
D．X-ray crystallography

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

A．Stomach(胃) and kidneys
B．Smooth muscle
C．Heart muscle
D．Intestinal epithelial tissue(肠表皮组织)