Question

Select the correct matching: Column I Column II A. \(\mathrm{G}_{1}\) Phase - 1\. Gap 1 Phase B. Cytokinesis 2\. Nuclear division C. Karyokinesis 3\. Cytoplasmic division D. S phase 4\. Synthesis phase (a) \(\mathrm{B}-1, \mathrm{C}-2, \mathrm{~A}-3, \mathrm{D}-4\) (b) A-1, C-2, B-3, D - - (c) \(\mathrm{D}-1, \mathrm{C}-2, \mathrm{~B}-3, \mathrm{~A}-4\) (d) \(\mathrm{A}-1, \mathrm{D}-2, \mathrm{~B}-3, \mathrm{C}-4\)

Short answer

The correct matching is (b) A-1, C-2, B-3, D -4

Step-by-step solution

Identify each term

G1 Phase, denoted by \(\mathrm{G}_{1}\), is the Gap 1 Phase during cell division. Cytokinesis is cytoplasmic division. Karyokinesis specifically refers to nuclear division and S phase is the synthesis phase where DNA replication occurs.

Match each term with their correct descriptions

From the previous step, the correct matching is \(\mathrm{A}-1\) for G1 Phase, \(\mathrm{B}-3\) for cytokinesis, \(\mathrm{C}-2\) for karyokinesis, and \(\mathrm{D}-4\) for S phase.

Find the correct Option

From the given options, select the option which matches the pairing found in Step 2. The correct answer is (b) A-1, C-2, B-3, D -4

Key concepts

G1 Phase

The G1 Phase, or Gap 1 Phase, is a critical part of the cell cycle where cells grow and carry out normal functions. After a cell is born from cell division, it enters the G1 phase, which is crucial for the buildup of energy and the synthesis of proteins necessary for DNA replication and cell division. It's a period of assessment where the cell checks for DNA damage and ensures that all systems are ready before moving on to the DNA synthesis phase, known as S phase.

The G1 phase varies in length among different cell types, and not all cells proceed from G1 to the S phase; some may enter a resting state called G0 phase. In a broader context, understanding the G1 phase's regulatory mechanisms is vital for cancer research and therapeutic developments as errors during this phase can lead to uncontrolled cell division.

Cytokinesis

Cytokinesis is the process by which the cytoplasm of a single eukaryotic cell divides to form two daughter cells. This occurs after karyokinesis, the division of the cell's nucleus, and is the final step in the cell cycle. During cytokinesis, the cell's cytoskeleton, particularly actin filaments and myosin, creates a structure known as the contractile ring.

The contractile ring pulls the cell membrane inward, pinching the cell into two separate entities, each containing one nucleus. This physical division is essential for maintaining the appropriate size of cells and for ensuring that each daughter cell has a full set of organelles and sufficient cellular machinery to function independently.

Karyokinesis

Karyokinesis refers to the division of a cell's nucleus and is a form of mitosis. It is during karyokinesis that the cell's genetic material, contained within the nucleus, is carefully duplicated and equally partitioned between two new nuclei. The process is meticulously coordinated and involves several stages: prophase, metaphase, anaphase, and telophase.

Each phase ensures that the chromosomes are accurately separated and organized so that each daughter cell inherits a complete set of genes. Errors in karyokinesis can lead to genetic disorders or contribute to the development of cancer, making it a critical process to understand for genetics and medical research.

S phase

The S phase, short for Synthesis phase, is dedicated to DNA replication. During this period, the entire genome is duplicated to ensure each daughter cell receives an identical copy of the genetic material. This phase is characterized by a high level of biochemical activity within the nucleus as enzymes like DNA polymerase and helicases spring into action.

The fidelity of DNA replication during the S phase is extremely important to prevent mutations that could lead to diseases such as cancer. The S phase is often followed by a checkpoint where the cell verifies that DNA synthesis has been accurately completed before transitioning into the phases of mitosis where the cell will ultimately divide, sharing the replicated DNA between the two daughter cells.