a. the nuclear envelope is a barrier between the spindle and the chromosomes. b. the nuclear envelope would block movement of chromosomes, especially during anaphase and telophase.
Does nuclear envelope dissolve during anaphase?
During prophase, the chromosomes condense and the nuclear envelope dissolves. During metaphase, the chromosomes align at the center of the cell. During anaphase, the sister chromatids are separated and pulled to opposite ends of the cell.
Is the nuclear membrane present in prophase?
The nuclear membrane is thus absent during prophase, metaphase, and telophase. The nuclear membrane is present (and essential) during all periods of interphase. The main functions of interphase are the synthesis of cellular proteins, DNA replication, and cellular growth.
What is a nuclear envelope in a cell?
The nuclear envelope (NE) is a highly regulated membrane barrier that separates the nucleus from the cytoplasm in eukaryotic cells. It contains a large number of different proteins that have been implicated in chromatin organization and gene regulation.
Which cells do not contain a nuclear envelope?
Prokaryotes are organisms whose cells lack a nucleus and other organelles. Prokaryotes are divided into two distinct groups: the bacteria and the archaea, which scientists believe have unique evolutionary lineages.
How nucleus is formed?
The vesicles first fuse to form membranes around individual chromosomes, which then fuse with each other to form a complete single nucleus.
What is meant by prophase?
Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses.
What would happen if the nuclear envelope did not dissolve?
What might happen if the nuclear envelope of a cell did not break down during mitosis? The cytoskeleton could not attach to the chromosomes and the mitotic spindle would not form.
Why does the nuclear membrane dissolve?
The nuclear envelope of metazoa breaks down at the onset of mitosis and reassembles at the end of mitosis. This process is mainly controlled by the cyclin-dependent kinase that phosphorylates inner nuclear membrane (INM) proteins to disrupt their association with chromatin and to disintegrate the nuclear lamina.
Why can’t you see a nuclear membrane during metaphase?
The nuclear envelope does not disappear in metaphase of mitosis, because it already did in prophase. The nuclear envelope is a large and complex structure and not just a floppy membrane pouch. The inner surface of the nucleus has a protein skeleton that helps give the nucleus its shape.