Problem 6 - Biology Today and Tomorrow with Physiology

Question

Interphase is the part of the cell cycle when ________. a. a cell ceases to function b. a cell forms its spindle apparatus c. a cell grows and duplicates its DNA d. mitosis proceeds

Step-by-Step Solution

Answer

Interphase is when a cell grows and duplicates its DNA (option c).

Step 1: Understand the Cell Cycle

The cell cycle is a series of stages through which a cell passes to divide and produce new cells. It consists of interphase and mitotic phase (mitosis).

Step 2: Define the Interphase

Interphase is the first main phase of the cell cycle, during which the cell prepares for division. It includes the G1, S, and G2 phases.

Step 3: Identify Key Functions During Interphase

During interphase, the cell grows, performs its normal functions, and duplicates its DNA so it can divide. This is essential for the cell to prepare for mitosis.

Step 4: Review Each Option

- Option a: Incorrect, because the cell continues to function during interphase. - Option b: Incorrect, spindle apparatus formation happens during mitosis, not interphase. - Option c: Correct, as it describes cell growth and DNA duplication during interphase. - Option d: Incorrect, because mitosis occurs after interphase.

Step 5: Conclusion

From the analysis, the correct answer is that interphase is when a cell grows and duplicates its DNA, aligning with answer c.

Key Concepts

Interphase

Interphase is a crucial phase within the cell cycle, taking up the majority of a cell's life. This is the stage where the cell is busy with substantial growth and preparation for division. The interphase is often misunderstood to mean a restful period; however, this is not the case.

• During interphase, the cell focuses on growth, performing its specific functions, and preparing for the next stages of the cell cycle.
• Interphase is composed of three sub-phases: G1, S, and G2. Each of these has its own unique responsibilities.

This is the period where the cell makes the vital decision to duplicate its contents, including the all-important DNA, to ensure that each daughter cell receives an accurate set of genetic material.

DNA Duplication

DNA duplication, or DNA replication, is a central event during the interphase, specifically occurring in the S phase (Synthesis phase). This biological process is critical for cell division.

When DNA duplicates:

• The cell produces an identical copy of each DNA molecule, ensuring both new cells have the same genetic information.
• Enzymes like DNA polymerase work as the architects that guide the formation of the new DNA strands.

The replication process is tightly controlled, protecting against mutations and maintaining the integrity of the genetic code as it prepares for the subsequent phase of mitosis.

Mitosis

Mitosis is the exciting phase where the preparatory work during interphase comes to fruition. It is the phase where the parent cell divides to produce two genetically identical daughter cells.

Here's what happens during mitosis:

• The spindle apparatus, which was not needed during interphase, forms and helps segregate the duplicated chromosomes.
• Chromosomes align in the middle of the cell before being separated into the two new nuclei.
• Mitosis ensures each new cell has the same number and type of chromosomes as the original cell.

After mitosis, cells often go back into interphase, continuing the vital cycle of growth, function, and replication.