Cell division is a fundamental biological process that underlies growth, development, and tissue repair in all living organisms. It is a carefully regulated process that ensures the continuation of life by creating new cells. In this blog post, we will learn about the basics of cell division, cell cycle, mitosis, meiosis, and regulation of cell division.
The cell cycle:-
The cell cycle is an organized sequence of events whereby a cell divides to form two daughter cells. It involves several steps, including:
G1 (Gap 1 phase):
This is the first phase after a cell is born or divides. During this phase, the cell grows in size and performs its normal functions.
S (synthesis phase):
In this phase, DNA replication occurs, resulting in the formation of two identical sets of chromosomes.
G2 (Gap 2 phase):
This phase occurs after DNA synthesis. The cell continues to grow, and it checks for any errors in DNA replication.
M (mitotic phase):
The M phase is further divided into four phases: prophase, metaphase, anaphase, and telophase. These stages are collectively known as mitosis.
Mitosis:-
Mitosis is the process by which a eukaryotic cell divides into two identical daughter cells. Let's take a closer look at each step:
Prophase:
During prophase, chromatin condenses into visible chromosomes, each consisting of two sister chromatids bound together at the centromere. The nuclear envelope starts breaking.
Metaphase:
The chromosomes align along the equatorial plane of the cell, known as the metaphase plate. Spindle fibers from opposite poles attach to each chromatid, ensuring equal distribution.
Anaphase:
Sister chromatids are separated by short spindle fibers, and they move toward opposite poles of the cell.
Telophase:
In this final stage, the separated chromatids reach the poles, and the nuclear envelope forms again around each set, forming two separate nuclei.
Meiosis
Meiosis is a specialized form of cell division that occurs in sexually reproducing organisms, resulting in the formation of gametes (sperm and egg cells) with half the chromosome number of the parent cell. It consists of two divisions (meiosis I and II) and leads to genetic diversity.
Regulation of cell division:-
Cell division is precisely regulated to prevent errors that could lead to cancer or other disorders. Key players in this regulation include cyclins and cyclin-dependent kinases (CDKs). Cyclins activate CDKs, which, in turn, trigger specific events in the cell cycle. Checkpoints, such as the G1 checkpoint, ensure that the cell is ready to proceed to the next stage.
