Question

\(\mathrm{G}_{0}\) phase is characterized by (a) DNA duplication (b) Active metabolism (c) S-phase (d) M-phase

Short answer

The characteristic feature of G0 phase is (b) Active Metabolism.

Step-by-step solution

Understanding the Cell Cycle and its Phases

The cell cycle is divided into four primary phases: G1 (Gap 1), S (synthesis), G2 (Gap 2), and M (mitosis). There is a special phase called G0 (Gap 0) which represents a phase where cells have exited the cycle and have stopped dividing.

Analysing the Given Options

The given options may correspond to different phases of the cell cycle. (a) DNA duplication: This happens during the S-phase. (b) Active metabolism: In G1 phase, the cell grows and metabolism is very active. (c) S-phase: This is a phase, not a characteristic. (d) M-phase: This is another phase, not a characteristic.

Identifying the Correct Option for G0 phase

The G0 phase is a stage where the cell exists from the cycle and stops dividing. During this phase, the cell remains metabolically active. Hence, the appropriate characteristic which matches with G0 phase is (b) Active Metabolism

Key concepts

Understanding the Cell Cycle

The cell cycle is an essential process that allows cells to grow, replicate their DNA, and divide into two daughter cells. It is divided into distinct phases to organize these complex tasks efficiently. Let's explore these stages:

• G1 Phase (Gap 1): The first stage of the cell cycle. During this phase, cells grow larger, produce more proteins, and duplicate organelles. This phase is characterized by its high metabolic activity as the cell prepares materials needed for DNA synthesis.
• S Phase (Synthesis): In this phase, the duplication of DNA occurs. Each chromosome replicates to form identical sister chromatids crucial for cell division.
• G2 Phase (Gap 2): Following DNA synthesis, the cell continues to grow. It makes final preparations before dividing, such as synthesizing microtubules and other proteins.
• M Phase (Mitosis): The phase where actual cell division takes place. The cell's duplicated chromosomes are equitably divided between two daughter cells.

Another important phase related to the cell cycle is the G0 phase. This is a resting state where cells exit the cycle and stop dividing but remain metabolically active.
Understanding these phases helps us comprehend how cells maintain their vitality and regenerate tissues.

The Process of Cell Division

Cell division is a crucial biological process where a single parent cell divides into two or more daughter cells. This process not only fuels growth but also plays a pivotal role in repairing damaged tissues. Here's a breakdown of the main types of cell division:

• Mitosis: This is a type of cell division meant for growth and maintenance of somatic (non-reproductive) tissues. It results in two genetically identical daughter cells from a single parent cell, ensuring that the genetic material is equally distributed.
• Meiosis: Occurring in germ-line cells, meiosis leads to the production of gametes (sperm and eggs). This process reduces the chromosome number by half, facilitating genetic diversity through recombination and independent assortment.

During cell division, particularly during mitosis, five distinct stages ensure precise replication and separation:

• Prophase: Chromosomes condense and become visible, and the spindle fibers start to form.
• Metaphase: Chromosomes line up at the cell's equator, attached to spindle fibers.
• Anaphase: Sister chromatids are pulled apart to opposite poles of the cell.
• Telophase: A nuclear membrane reforms around each set of chromosomes at each pole.
• Cytokinesis: Finally, the cell's cytoplasm divides, resulting in two separate cells.

Cell division ensures that organisms can grow, maintain their bodies, and reproduce. Each phase and type of division has its significance in life's continuity.

Role of Active Metabolism

Active metabolism refers to the continuous process where cells transform nutrients into energy and other necessary molecules. This is crucial, not only during the cell cycle but also in maintaining all cell functions:

• Energy Production: Cells generate ATP through metabolic pathways like glycolysis, Krebs cycle, and oxidative phosphorylation, providing the energy required for various cellular activities.
• Biosynthesis: Metabolism supports the synthesis of macromolecules needed by the cell, including proteins, lipids, nucleic acids, and carbohydrates. These molecules are essential for cell structure, function, and regulation.
• Cell Growth and Division: During the G1 and G2 phases of the cell cycle, an actively metabolizing cell grows, repairs damages, and builds up resources needed for successful DNA replication and division.

In the G0 phase, even though the cell has exited the division cycle, it remains metabolically active. This allows the cell to function properly, repair itself if necessary, and respond to signals that may draw it back into the cell cycle for further division.
Active metabolism is the lifeline of a cell, as it continuously supplies energy and components needed for survival, adaptation, and functioning of the cell.