1 . Cyclic AMP is produced by the enzyme________and degraded by the
enzyme________
2 . NO是一种气体信号分子,在体内主要由精氨酸产生, 它的半衰期很短, 故只作用于邻近细胞, 它作用的靶酶是________
3. ________junctions enable cells to get a hold on the extracellular matrix by connecting their actin filaments to the matrix.
4 动物细胞质膜靠________建立膜两侧的质子动力势，而植物细胞则是靠________。
5. 蛋白质合成时多聚核糖体的形成对生命活动的意义在于：________。