Cell Cycle & its Phases Video Lecture | AP Biology - Grade 9

Ans. The cell cycle refers to the series of events that take place in a cell leading to its division and the production of two daughter cells. It consists of several phases, including interphase (G1, S, and G2 phases) and mitosis (prophase, metaphase, anaphase, and telophase).

Ans. The cell cycle consists of several phases. During interphase, the cell grows, replicates its DNA, and prepares for division. It is further divided into three subphases: G1 phase (growth and preparation), S phase (DNA replication), and G2 phase (further growth and preparation). The next phase is mitosis, where the cell's nucleus divides into two identical daughter nuclei. Mitosis is divided into four stages: prophase, metaphase, anaphase, and telophase.

Ans. In the G1 phase, the cell grows and carries out its normal functions. In the S phase, DNA replication occurs, resulting in the duplication of the cell's genetic material. The G2 phase follows, during which the cell continues to grow and prepares for division. In mitosis, the cell's nucleus divides. Prophase involves the condensation of chromosomes and the breakdown of the nuclear envelope. During metaphase, the chromosomes align in the middle of the cell. Anaphase is characterized by the separation of sister chromatids, which move towards opposite poles of the cell. Finally, in telophase, the nuclear envelope reforms, and the cell begins to divide.

Ans. The cell cycle is crucial for the growth, development, and maintenance of organisms. It allows cells to divide and produce new cells for tissue repair, growth, and reproduction. It also ensures that genetic material is accurately replicated and distributed to daughter cells, maintaining genetic stability. Proper regulation of the cell cycle is essential to prevent errors in DNA replication and division, which can lead to genetic disorders and diseases, including cancer.

Ans. The cell cycle is tightly regulated by various checkpoints and regulatory proteins. These checkpoints ensure that each phase of the cell cycle is completed accurately before proceeding to the next phase. Cyclins and cyclin-dependent kinases (CDKs) are crucial regulators that control the progression of the cell cycle. They form complexes that activate specific proteins required for cell cycle events. Additionally, tumor suppressor genes and oncogenes play a role in regulating the cell cycle by promoting or inhibiting its progression.