Cell Cycle and Cell Division - Topics, Definition And Phases of Cell Cycle

The chapter "Cell Cycle and Cell Division" discusses the basic process through which cells develop and divide. This process is essential to understanding how living organisms mature, grow, and reproduce. The chapter mainly deals with the various phases of the cell cycle—interphase and the mitotic (M) phase, and the two major types of cell division: mitosis and meiosis. This article focuses on the basic terminology, key concepts of the cell cycle and its phases, types of cell division, and their importance. It is an important chapter in Class 11 Biology.

This Story also Contains

1. History of Cell Cycle and Cell Division
2. Cell Cycle and Cell Division
3. Stages of the Cell Cycle
4. Events of the Cell Cycle
5. Diagram of the Cell Cycle
6. Cell Division Importance

Important Topics of Cell Cycle and Cell Division

This chapter covers important topics such as phases of the cell cycle—G₁, S, G₂, and M phase and detailed stages of mitosis and meiosis. The importance of each type of division and how both divisions play a role in growth and reproduction are also discussed. The cell cycle is regulated by checkpoints such as cyclins and Cdks. The topics are listed below:

• Phases of the Cell Cycle
• Regulation of the Cell Cycle
• Importance of Cell Division

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• Difference Between Mitosis and Meiosis
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History of Cell Cycle and Cell Division

A frog zygote was studied by Prevost and Dumas (1824) while they discovered the cell cycle. It is a series of steps through which the cell passes to divide and produce new cells. It is the entire process by which a population of cells grows and develops with the help of a single parent cell. Some of the important historical context about the cell cycle and its development is discussed below in the table:

Cell Cycle and Cell Division

The cell cycle is a series of events which happen when the cell grows and divides. It is a process by which a cell divides into daughter cells after distributing its genetic material and cytoplasm.

Some of the key features of the cell cycle are mentioned below:

• The longest phase of the cell cycle is interphase, in which the DNA replicates itself.

• There are three phases of interphase: G1 Phase, S Phase and G2 Phase.

• In the mitotic phase, the cell divides into two daughter cells.

• The G0 phase is also called the resting or quiescent phase, as the cell either exits the cycle temporarily or permanently.

• The cell cycle is essential for growth, tissue repair and asexual reproduction in unicellular organisms.

• An average human cell cycle lasts about 24 hrs.

• The cell cycle is tightly regulated, which makes sure that accurate DNA is replicated for the division.

Stages of the Cell Cycle

Before the process of the cell cycle, a cell must fulfil certain criteria: It must grow, duplicate its genetic material (DNA), and physically split into two sister cells. These steps are performed in an organised manner by the cells, which is known as the cell cycle.

The stages of the cell cycle are divided into two major phases, interphase and mitotic (M) phase. Some of the important stages are mentioned below:

• G1 Phase: The cell doubles its organelles and prepares itself for DNA replication.
• S Phase: DNA replication takes place with the formation of two sister chromatids.
• G2 Phase: The cell continues the grow for the final preparation of mitosis.
• M Phase: Mitosis takes place, which is followed by cytoplasmic division or cytokinesis.

Events of the Cell Cycle

The cell cycle and cell division class 11 chapter explains the chain of events, and each one of them is important. All the important events and their significance in the replication process are discussed below in the table.

Diagram of the Cell Cycle

The diagrammatic representation of the cell cycle will help you to have a better understanding of every stage and process involved in the cycle. The cell cycle is divided primarily into 4 phases- G₁, S, G₂, and M phase. M-phase is further divided into prophase, metaphase, anaphase, and telophase, collectively called karyokinesis. Then, the cytoplasm divides, a process called cytokinesis.

Diagram of Mitosis

Mitosis is a type of cell division that results in two genetically identical daughter cells, used for growth and repair. The diagram of cell division given below will help you to have a better understanding of every stage involved in mitosis.

Diagram of Meiosis

Meiosis is a type of cell division that reduces the chromosome number by half, producing four genetically different gametes for sexual reproduction. The diagram of cell division given below will help you to have a better understanding of every stage involved in meiosis.

Cell Division Importance

Cell division takes place through mitosis and meiosis and is one of the very important events for the growth and repair of the body tissues and muscles. Apart from this, it is also very important for reproduction in organisms. Some of the major importance of cell division is discussed below:

• In mitosis, diploid daughter cells are produced with identical genetic material.
• In meiosis, gametes are formed, such as sperm and eggs.
• It supports growth and tissue repair.
• The cell division also ensures that there is the growth of multicellular organisms and the restoration of the nucleus to cytoplasm ratio.
• Due to cell division, damaged and dead cells are replaced with healthy ones. This is usually done by the skin, gut lining and blood cells.
• Due to cell division, there is continuous plant growth through lateral and apical meristematic tissues.
• Due to cell division, there is also preservation of chromosomes. This is usually done in sexually reproducing organisms and increases the genetic variation.

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