Problem 7 - Biology

Question

Cell plate formation usually begins during (a) telophase in a plant cell (b) telophase in an animal cell (c) \(\mathrm{G}_{2}\) in a plant cell (d) \(\mathrm{G}_{2}\) in an animal cell (e) a and b are correct

Step-by-Step Solution

Answer

Option (a): Cell plate formation begins during telophase in a plant cell.

Step 1: Understanding Cell Division

During cell division, particularly in mitosis, the cell undergoes several phases: prophase, metaphase, anaphase, and telophase. In plant cells, telophase involves the start of cell plate formation.

Step 2: Cell Plate Formation Specifics

Cell plate formation is specific to plant cells. During telophase, the cell plate begins to form as vesicles from the Golgi apparatus coalesce at the equatorial plane, eventually leading to the formation of a new cell wall that separates the two daughter cells.

Step 3: Analyzing the Options

Looking at the given options: (a) is correct because cell plate formation occurs during telophase in plant cells. (b) is incorrect; animal cells do not form cell plates. (c) and (d) refer to the G2 phase, during which cell plate formation does not begin. (e) is incorrect as it suggests both (a) and (b) are correct.

Step 4: Selecting the Correct Answer

Given our analysis, the correct answer is (a) telophase in a plant cell, because cell plate formation specifically occurs in plant cells during this phase.

Key Concepts

Telophase

In the journey of cell division, telophase marks a critical endpoint for mitosis. Mitosis comprises several phases, including prophase, metaphase, anaphase, and eventually telophase, where each phase holds its unique purpose. Telophase is significant because it signals the reformation of the nuclear envelope around the chromosomes that have reached the cell’s poles.
Gradually, the chromatin de-condenses, making the chromosomes nearly invisible under a microscope.

• Chromosomes arrive at opposite ends of the cell.
• Nuclear membranes reform around the two sets of chromosomes.
• The cell begins to re-establish its normal structures.

During telophase, the cell also typically starts another process that leads to the cell's final division, marking the end of mitosis as the cell transitions to cytokinesis.

Plant Cells

Plant cells are distinguished by several unique structures, contributing to their specific functions compared to animal cells. These cells possess a rigid cell wall made primarily of cellulose, providing protection and maintaining plant rigidity. Inside plant cells, chloroplasts play a vital role in carrying out photosynthesis to convert sunlight into energy.

• Cells have a rigid cell wall providing structural support.
• Chloroplasts are present for photosynthesis.
• They also have a large central vacuole for storage and maintaining turgor pressure.

During cell division, plant cells exhibit a unique mechanism involving cell plate formation, which will be discussed later, distinguishing them further in the process of cytokinesis from animal cells.

Cell Plate Formation

Cell plate formation is a decisive phase in plant cell cytokinesis, distinguishing their division process from that of animal cells. This process begins during telophase when vesicles from the Golgi apparatus migrate to the cell's center. These vesicles coalesce at the midline, starting the development of a new section between the two daughter cells.

• The cell plate is initiated by the fusion of Golgi-derived vesicles.
• Gradually, additional vesicles join, expanding the plate across the dividing cell.
• Eventually, this grows into a new cell wall, fully partitioning the two cells.

This intricate process ensures that each daughter cell becomes entirely separated, equipped with its own membrane and cell wall, marking the conclusion of cell division in plant cells.