The cell division cycle is a series of events occurring within a cell that leads to its development and division. Cell division makes up for the dead, diseased, or injured cells.
The cell cycle is also known as the cell division cycle. It is a series of processes in a cell as it grows and divides into two offspring daughter cells. The steps include duplicating DNA cells and separating the cytoplasm and other cellular contents into identical daughter cells. The mechanism of the cell cycle was first discovered by the scientist named Dumas and Prevost in 1824 while researching the cleavage of a frog's zygote. As we shall see below, this cycle passes through a series of stages and steps to separate, divide, and produce new cells from the parent ones.
A eukaryotic cell cycle takes about 24hrs to complete one growth and division cycle, with Mitosis taking up 30% of this time. All eukaryotic cell cycles are divided into two main stages:
I) Interphase (G1, S, and G2)
II) Mitosis Phase
Before these 2 phases, there is another phase called the G0 Phase or Quiescence. This is a resting phase where all cells have left their cell cycles and stopped division. Some eukaryotic cells enter this phase and remain here for a very long time or even indefinitely performing assigned duties. This phase is a very common phase for the cells that are differentiated to their utmost capacities.
Here, the cell prepares for cell division by experiencing cell growth and replication of DNA. Interphase takes up about 90% of the time of the overall cycle, and it is divided into three stages:
1. G1 Phase: The Gap 1 phase is between mitosis and the replication of genetic materials. Here, the cell is active metabolically and continues its growth without DNA replication.
2. S Phase: This is also called the Synthesis phase. DNA replication occurs during this stage. A normal diploid somatic cell with a 2N complement of DNA at the beginning of the S phase acquires a 4N complement at its end. The process of RNA transcription, as well as protein synthesis in this phase, is almost NIL.
3. G2 Phase: The Gap 2 phase is a stage of rapid cell growth and protein synthesis, which helps prepare the cells for mitosis. There is spindle formation, cell organelle multiplication, etc.
II) Mitosis Phase:
It is also called the phase of equational division. In this phase, the cell undergoes reorganization and is divided into offspring. These offsprings have the same chromosome numbers as their parents. Mitosis plays a role in growth, tissue repair, and asexual reproduction. This phase is divided into the following phases:
1. Prophase features:
2. Metaphase features:
3. Anaphase features:
4. Telophase features:
This phase follows the mitosis phase. The cytoplasm undergoes division into two new daughter cells that are genetically identical to their parent cell. Cytokinesis in plant cells is more complex than animal cells.
In plant cells, a new cell wall is built between the daughter cells by the Golgi apparatus via a cell plate structure. Glucose and Golgi vesicles play a significant role in forming the cell wall.
In animal cells, cytokinesis occurs by a process known as cleavage through the formation of a cleavage furrow. The contraction of actomyosin filaments drives the separation of the cytoplasm into two cells.
1. What are the four stages of the cell cycle?
In eukaryotes, the 4 stages of the cell cycle are G1 Stage, S Stage, G2 Stage, and M Stage.
2. What is the difference between the G1 and G2 stages in the cell cycle?
G1 is the first growth stage for cell growth and normal metabolic roles, whereas G2 is the second stage for cell growth and preparation for mitosis.
3. What happens in the G1 stage of cell growth?
The G1 phase is between mitosis and the replication of genetic materials. Here, the cell is active metabolically and continues its growth without DNA replication.
4. What are the 3 phases of the cell cycle?
The 3 phases of the cell cycle are:
5. Which phase comes between the G1 and G2 stages?
The S phase or the Synthesis phase comes between G1 and G2 in the cell cycle. The replication of DNA takes place during this stage.
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