This is the unique short note on the high weightage chapter, cell cycle and cell division which must be read at least once by each fresh Neet aspirant.
What is cell cycle:
| Main Phase | Sub-Phase / Stage | Key Events & Characteristics |
|---|---|---|
|
Interphase (Longest phase / Metabolic stage) |
G₁ Phase (Gap 1) | Cell growth, duplication of cytoplasmic biomolecules, and cell organelles double. |
| S Phase (Synthesis) | DNA replication occurs; DNA content doubles, but the chromosome number remains the same (chromosomes become double-armed with two sister chromatids). | |
| G₂ Phase (Gap 2) | Further cell growth, synthesis of tubulin proteins, and duplication of major organelles to prepare for division. | |
|
M-Phase (Cell Division Phase) |
Prophase | Karyokinesis (Nuclear Division): Visible chromosomes arrange, align, and separate across these four sequential stages. |
| Metaphase | ||
| Anaphase | ||
| Telophase | ||
| Cytokinesis | Cytoplasmic division following nuclear division, completing the cell cycle. |
Just like our life cycle, newly formed cells start growing in size by doubling the cell contents. This growth phase involves Gap1,S and Gap2 phase, for duplication of cytoplasmic substances , DNA replication and synthesis of substances for the cell division respectively. These orderly events in sequence from formation to division of the cell are called cell cycles.
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Explore NEET Biology →Main steps of the Cell cycle:
The two main steps of cell cycle are,
Longest interphase,
M-phase or cell division phase
Interphase of cell cycle:
It is the so-called resting phase where no visible changes are found. But, this phase is energetically and metabolically the most active stage. Cytoplasmic biomolecules and most of the organelles double in G1 phase. DNA content doubles in synthetic phase but chromosome numbers remain same. This means each chromosome becomes double armed and shows two sister chromatids. In G2 phase cell syntheses tubulin proteins and duplicates major organelles.
Real Drama is Cell Division:
M-phase is the actual phase of division. Here, nuclear division is followed by cytoplasmic division. Chromosomes are visible and all events like arrangement and separation of chromosomes are studied through prophase,metaphase,anaphase and telophase respectively.
Drama ends cell cycle ends:
After cytoplasmic division, the cell divides into two cells . If the daughter cell has an equal number of chromosomes as the parent cell, it is called Mitosis. If, chromosome number is reduced to half, it is called Meiosis.
Final tips :
Mitosis occurs in all body cells for growth and development.
Meiosis occurs only for sexual reproduction. In higher plants Meiosis produces spores and in animals produce gametes.
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BotanysirHimansu