Cell Cycle – Class 12 | Chapter – 10 | Biology Short Notes Series PDF

A cell cycle is a series of events that takes place in a cell as it grows and divides. A cell spends most of its time in what is called interphase, and during this time it grows, replicates its chromosomes, and prepares for cell division. The cell then leaves interphase, undergoes mitosis, and completes its division. The resulting cells, known as daughter cells, each enter their own interphase and begin a new round of the cell cycle.

The cell cycle is a cycle of stages that cells pass through to allow them to divide and produce new cells. It is sometimes referred to as the “cell division cycle” for that reason.

New cells are born through the division of their “parent” cell, producing two “daughter” cells from one single “parent” cell.

Daughter cells start life small, containing only half of the parent cell’s cytoplasm and only one copy of the DNA that is the cell’s “blueprint” or “source code” for survival. In order to divide and produce “daughter cells” of their own, the newborn cells must grow and produce more copies of vital cellular machinery – including their DNA.

The two main parts of the cell cycle are mitosis and interphase.

Mitosis is the phase of cell division, during which a “parent cell” divides to create two “daughter cells.”

The longest part of the cell cycle is called “interphase” – the phase of growth and DNA replication between mitotic cell divisions.

Both mitosis and interphase are divided into smaller sub-phases which need to be executed in order for cell division, growth, and development to proceed smoothly. Here we will focus on interphase, as the phases of mitosis have been covered in our “Mitosis” article.

Interphase consists of at least three distinct stages during which the cell grows, produces new organelles, replicates its DNA, and finally divides.

Only after the cell has grown by absorbing nutrients, and copied its DNA and other essential cellular machinery, can this “daughter cell” divide, becoming “parent” to two “daughter cells” of its own.

Functions of Cell Cycle

Because cells reproduce by dividing, new “daughter” cells are smaller than their parent cells, and may inherit the bare minimum of cellular machinery they need to survive.

Before these daughter cells can divide to produce still more cells, they need to grow and reproduce their cellular machinery.

The importance of the cell cycle can be understood by doing simple math about cell division. If cells did not grow in between divisions, each generation of “daughter” cells would be only half the size of the parent generation. This would become unsustainable pretty quickly!

In order to accomplish this growth and prepare for cell division, cells divide their metabolic activities into distinct phases of Gap 1, Synthesis, Gap 2 between cell divisions.

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By Team Learning Mantras