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Have you ever witnessed the transformation of a caterpillar into a butterfly? If that’s the case, you’re probably aware of the concept of a life cycle. Butterflies go through some stunning life cycle transitions, changing from a worm-like creature to a pupa, and then to a lovely creature that floats on the breeze. Humans, plants, and microorganisms all have a life cycle, which is defined as a series of developmental processes that an individual goes through from conception to reproduction.
A cell’s life cycle is referred to as the cell cycle. In other words, it’s the process of growth and development steps that a cell goes through between “birth”—the division of a mother cell—and reproduction—the division of two new daughter cells.
The cell cycle’s stages
A cell must perform many crucial activities in order to divide: it must grow, duplicate its genetic material (DNA), and physically split into two daughter cells. The cell cycle is an orderly and predictable series of phases in which cells fulfil various functions. The cell cycle is a cycle rather than a linear pathway because the two daughter cells can restart the process from the beginning at the end of each cycle.
The stages of the cell cycle of eukaryotic cells, or cells with a nucleus, are separated into two major phases: interphase and mitotic (M) phase.
The cell develops and duplicates its DNA during interphase
During the mitotic (M) phase, the cell splits its cytoplasm and divides its DNA into two sets, resulting in the formation of two new cells
The Interphase Stages
Gap 1
After the chromosomes have been separated and the cell membrane has been divided by cytokinesis, the two new cells enter the first stage of interphase, Gap 1 or G1. The cell conducts its regular duties and expands in size at this period. Organelles are replicated as needed by the cell. Cells can occasionally leave G1 and enter G0, or resting phase, as seen in the diagram above. If the cell is actively dividing, it will enter the next step of synthesis to continue interphase.
Synthesis
The cell stops working normally during synthesis. All resources are devoted to DNA replication. The process begins with several proteins “unzipping” the two intertwined DNA stands. Polymerase enzymes, which are other proteins, begin producing new strands to pair with either half of the DNA. This is done on each chromosome, resulting in sister chromatids, which are identical copies of each other. If the cell is a somatic cell, it will start mitosis following interphase and the sister chromatids will be split, resulting in each cell having two identical copies of the genome. After interphase, if the cell produces a gamete, it will enter meiosis. In meiosis, homologous chromosomes are separated in one division, followed by sister chromatid separation in the next, resulting in cells with only half of a complete genome. These cells reach interphase, but the synthesis step cannot begin until another gamete is fertilised. In any case, the cell must prepare for cell division after synthesis.
Gap 2
The cell enters a second gap stage, known as Gap 2 or G2, after the DNA has been copied during the synthesis stage. The cell gains bulk to the cytoplasm and copies numerous essential organelles during G2. Mitochondria are duplicated in animals to provide enough energy for dividing cells. In plants, both the mitochondria and the chloroplasts must be reproduced in order to deliver energy-producing organelles to the daughter cells.
M phase
The cell divides its copy DNA and cytoplasm to form two new cells during the mitotic (M) phase. Mitosis and cytokinesis are two separate division-related mechanisms that occur during the M phase.
The mitotic spindle, a specialised structure made up of microtubules, pulls apart the cell’s nuclear DNA into visible chromosomes during mitosis. Prophase (also separated into early prophase and prometaphase), metaphase, anaphase, and telophase are the four stages of mitosis. In the video on mitosis, you may learn more about these stages.
The cytoplasm of the cell is split in two during cytokinesis, resulting in the formation of two new cells. Cytokinesis normally begins shortly after mitosis ends, with some overlap. Importantly, cytokinesis occurs in animal and plant cells in distinct ways.
Mitosis
Mitosis is the process by which a eukaryotic cell divides into two distinct but comparable nuclei by separating its nuclear DNA and chromosomes. A mitotic spindle, which is a specialised structure made up of microtubules, pulls the chromosomes apart.
Cytokinesis
The cell’s cytoplasm divides during this phase. It starts as soon as mitosis is completed. Plant cells have a stiff cell wall and a high internal pressure, making them much tougher than animal cells. As a result, cytokinesis happens differently in plant and animal cells.
Conclusion
A cell’s life cycle is referred to as the cell cycle. In other words, it’s the process of growth and development steps that a cell goes through between “birth”—the division of a mother cell—and reproduction—the division of two new daughter cells.
