Question

How do the daughter cells at the end of mitosis and cytokinesis, compare with their parent cell when it was in $G_1$ of the cell cycle?
a. The daughter cells have half the amount of cytoplasm and half the amount of DNA.
b. The daughter cells have half the number of chromosomes and half the amount of DNA
c. The daughter cells have the same number of chromosomes and half the amount of DNA
d. The daughter cells have the same number of chromosomes and same amount of DNA

Answer 1

The period or phase between the two mitotic divisions is called interphase. It is divided into three sub-stages that are $G_1$- phase, S- phase, $G_2$- phase. In the $G_1$-phase the cell grows in size but there is no duplication of genetic material. In the S-phase i.e. synthesis phase there is a duplication of DNA material.

Complete answer:
- During the $G_1$-phase of interphase, which represents the gap between the mitosis and initiation of S-phase, the cell grows in size but there is no duplication of genetic material.
- In S-phase, there is the duplication of the DNA material i.e. a phase where actual DNA synthesis takes place. There is no increase in the chromosome number.
- In the $G_2$-phase, the synthesis of DNA stops, and protein required for the mitosis are synthesized.
- Mitosis- It is the type of division on which the chromosomes replicate themselves and are divided equally into two daughter cells.
- After the cell division is complete each daughter cell receives chromosomes that are identical to those in the original nucleus.

Hence, the correct answer is option (D).

Additional information:
Mitosis involves the following main phases:
•Prophase- Chromosomes condense. Spindle fibers form and chromosomes move toward opposite poles.
•Metaphase- The disintegration of a nuclear envelope. The chromosomes are the shortest and thickest of all.
•Anaphase- Sister chromatids separate and move toward the opposite pole.
•Telophase- Nuclear membrane for cell division begins to form.

Note: Synthesis phase (S-phase) is the most important phase of the cell cycle as it represents the duplication of DNA material, i.e. it is the phase where actual DNA synthesis takes place. After this the cell undergoes mitosis, a type of division in which chromosomes replicate themselves and get divided equally into the two daughter cells.