Cell Cycle And Cell Division Class 11 Notes - Chapter 10

It is a universally accepted fact that the cell is the most basic, structural and functional unit of life. A cell could be an individual organism by itself (such as an amoeba) or the cells could be a part of a larger organism (such as a cat). But how does this fundamental unit multiply for growth or repair? And what happens when the mechanisms that control the division of cells fail?

What is the Cell Cycle?

Essentially, the cell cycle is an orderly sequence of events that occur before the cell actually divides and gives rise to new cells. This is a very important process and has varying implications from growth and development to repair of the organism.

Mitosis

This is one of the two types of cell division where a single cell divides into two genetically identical daughter cells. In unicellular organisms, this type of cell division typically contributes to asexual reproduction. In multicellular organisms, mitosis is helpful for the growth and repair of damaged cells. Mitosis is also called equational division.

Meiosis

Also called reduction division, meiosis is another type of cell division that commonly occurs during sexual reproduction. Here, the chromosomes in the parent cell reduce by half, forming four gamete cells which are genetically distinct from the parent cells. Meiosis is very significant has it provides genetic diversity among a population.

When Cell Division Goes Wrong

Cells have many mechanisms that dictate when to divide and when to stop. When these mechanisms fail, the end result is usually cancer. Cells divide at the right time and at the right order. Such abnormalities can result in the chromosomes being damaged or destroyed. When cancer cells that are initially benign lose or gain faulty chromosomes, it can become malignant, often becoming life threating.

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Important Questions on Cell Cycle And Cell Division

What is Cytokinesis?

Cytokinesis is the process where the cytoplasm of a parental cell splits into two daughter cells. Moreover, the process occurs concurrently with meiosis and mitosis in animal cells.

Describe the quiescent phase of the cell cycle.

The quiescent phase refers to the G0 state where the cells reside in an inactive state (hence the term “quiescent”) before beginning with the cell cycle after activation in response to extrinsic signals.

What is mitosis?

Mitosis is a type of cell division where two daughter cells are formed possessing the same number and kind of chromosomes as their parent’s nucleus. It predominantly occurs during the growth of normal tissues.

What is the significance of meiosis?

Meiosis is very important because it ensures that the organisms which are born through sexual reproduction possess the correct number of chromosomes. If the number of chromosomes deviates from the standard, the organism may develop genetic abnormalities.

In conclusion, the two types of cell division, namely mitosis and meiosis have their own significance and functions. To learn more about cell cycle and cell division, register at BYJU’S.

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