【简答题】阅读以下程序代码,按输入语句右侧注释部分指定的数据输入,在各输出语句右侧注释部分写出对应输出结果,然后运行程序。 #include #include using namespace std; int main() { bool v; int a, m, n; double x, y, z, p, f; float f1 ; cin>> boolalpha >>v; // 输入: true c...
【多选题】How is the nuclear envelope supported by a meshwork of intermediate filaments?
A.
Whereas cytoplasmic intermediate filaments form ropelike structures, the intermediate filaments lining and strengthening the inside surface of the inner nuclear membrane are organized as a two-dimensional meshwork.
B.
The intermediate filaments that form this tough nuclear lamina are constructed from a class of intermediate filament proteins called lamins (not to be confused with laminin, which is an extracellular matrix protein). The nuclear lamina disassembles and reforms at each cell division, when the nuclear envelope breaks down during mitosis and then re-forms in each daughter cell.
C.
The collapse and reassembly of the nuclear lamina is controlled by the phosphorylation and dephosphorylation of the lamins.
D.
Phosphorylation of lamins by protein kinases weakens the interactions between the lamin tetramers and causes the filaments to fall apart. Dephosphorylation by protein phosphatases at the end of mitosis allows the lamins to reassemble.
【多选题】How does the nuclear envelope re-form at the telophase of M phase?
A.
By the end of anaphase, the chromosomes have separated into two equal groups, one at each pole of the spindle. During telophase, the final stage of mitosis, the mitotic spindle disassembles, and a nuclear envelope reassembles around each group of chromosomes to form the two daughter nuclei.
B.
Vesicles of nuclear membrane associate with the clustered chromosomes and then fuse to re-form the nuclear envelope.
C.
During this process, the nuclear pore proteins and nuclear lamins that were phosphorylated during prometaphase are now dephosphorylated, which allows them to reassemble and rebuild the nuclear envelope and lamina.
D.
Once the nuclear envelope has been re-established, the pores restore the localization of cytosolic and nuclear proteins and the condensed chromosomes decondense into their interphase state. A new nucleus has been created, and mitosis is complete. All that remains is for the cell to complete its division into two separate daughter cells.