Question

Which of the following options gives the correct sequence of events during mitosis?
A. Condensation → arrangement at equator → centromere division → segregation → telophase
B. Condensation → nuclear membrane disassembly → crossing over → Segregation → telophase
C. Condensation → nuclear membrane disassembly → arrangement at equator → centromere division → segregation → telophase
D. Condensation → crossing over → nuclear membrane disassembly → segregation → telophase

Answer 1

Hint:As you know, Mitosis is a part of the cycle of cell division. In this process, chromosomes of a cell are copied to form two identical sets of chromosomes, also the cell nucleus divides into two identical nuclei. But before mitosis, the cell forms an identical set of its own genetic information this is called replication. In the DNA is the genetic information of the chromosomes. In the beginning of mitosis the chromosomes are being wound up, and are then visible with a light microscope. Now, chromosomes are two chromatids which are joined at the centromere. Because these two chromatids are identical to each other they are referred to as sister chromatids.

Complete answer:
Now we already know, Mitosis is an important process where a single cell divides into two identical daughter cells (cell division). Major motive of mitosis is for growth and replacement of worn out cells. Always remember, mistakes made during mitosis can result in changes in the DNA that can result in genetic disorders.
Remember, The Mitosis is being classified into five phases:
Interphase: In this step, DNA in the cell is copied as to prepare for cell division, this results in two identical full sets of chromosomes. Whereas, outside of the nucleus, two centrosomes each have a pair of centrioles and these structures are important for the process of cell division. It’s important to know that during interphase, the microtubules extend from these centrosomes.
Prophase: In this step, chromosomes condense to make X-shaped structures and can be easily seen under a microscope. Chromosome each is composed of two sister chromatids, comprising identical genetic information. Now, chromosomes pair up so that both copies of chromosome 1 are together and both copies of chromosome 2 are together and like this so on. In the end prophase membranes around the nucleus in the cell are dissolved away releasing the chromosomes. The mitotic spindle, consisting of the microtubules and other proteins, extends across the cell in between the centrioles as they start to move towards opposite poles of the cell.
Metaphase: During this stage, the chromosomes line up nicely end-to-end along the centre also called the equator of the cell. Now, the centrioles are at opposite poles of the cell with the mitotic spindle fibres extending from them. The fibres of mitotic spindle attach to each of the sister chromatids.
Anaphase: Now, the sister chromatids are pulled apart by the mitotic spindles that pull one chromatid to one pole and another chromatid to the opposite pole.
Telophase: In this step, at each pole of the cell a full set of chromosomes come together, and a membrane is formed around each set of chromosomes to create two new nuclei. And occurs cytokinesis.
Now let’s discuss the final answer, Chromatin fibres first condenses to make chromosome at prophase and nuclear membrane start disappearing. Next in metaphase, all chromosomes aligned at the equator or centre and are attached to the spindle fibres with centromere. In anaphase, division of centromere and segregation of chromosomes happens at opposite poles of the nucleus then occurs telophase.

Additional information:
Mitosis in the cells of eukaryotic organisms is similar, but there are variations. Type "Closed" and "open" mitosis can be differentiated on the basis of the nuclear envelope remaining breaking down or intact. There’s an intermediate type in which we have partial degradation of the nuclear envelope and called "semi open" mitosis.

Therefore, the correct answer is option C

Note:- Keep in mind, Mitosis occurs only in eukaryotic cells. Prokaryotic cells that lack a nucleus, divide by a process referred to as binary fission. Most animal cells also undergo change in shape known as mitotic cell rounding, to get to a near spherical morphology at the start of mitosis.
Remember, most human cells are produced by mitotic cell division, but important exceptions include the gametes i.e. sperm and egg cells which are produced by meiosis. The gametes are made by a different kind of division referred to as meiosis.