Question

Arrange these in order of occurrence during mitosis:
1. Sister chromatids separate
2. Chromosomes align at the centre of the cell
3. Nuclear envelope disappears
4. Chromosomes undergo decondensation

• A. 1, 2, 3, 4
• B. 4, 1, 2, 3
• C. 3, 2, 1, 4
• D. 4, 3, 2, 1

Answer 1

The correct option is C 3, 2, 1, 4

Mitosis includes four phases - prophase, metaphase, anaphase and telophase.

During the prophase stage of mitosis, the chromatin undergoes coiling and packaging to form dense, compact, short structures known as chromosomes. This is called condensation which starts in prophase and gets completed by the end of the next stage, metaphase. The nuclear envelope also disappears during prophase.

This is followed by the alignment of chromosomes at the centre of the cell. This stage of mitosis is called metaphase.

Metaphase is followed by anaphase during which the centromere splits and sister chromatids separate and move to opposite poles.

The last phase of mitosis is telophase. During telophase, the chromosomes undergo decondensation. During decondensation, the DNA that is highly coiled gets uncoiled and gets freely dispersed in the nucleus and the chromosomes lose their identity. This leads to the formation of chromatin.