Problem 8 - Biology: The Unity and Diversity of Life

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

The correct answer is c. a cell grows and duplicates its DNA.

Step 1: Understanding Interphase

Interphase is a phase in the cell cycle. It is the portion of the cell cycle where the cell prepares for mitosis, but mitosis itself does not occur during interphase. Instead, the cell is undergoing a series of preparations to ensure it is ready for cell division.

Step 2: Examining Changes During Interphase

During interphase, the cell is actively engaged in metabolic processes. The most crucial activities include cell growth and the duplication of the cell's DNA, which are necessary for successful cell division during the next phase, mitosis.

Step 3: Analyzing Options

Compare each provided option to what happens during interphase: - **a.** A cell ceases to function: This doesn't happen during interphase; cells remain actively functioning. - **b.** A cell forms its spindle apparatus: This occurs later, during mitosis, not interphase. - **c.** A cell grows and duplicates its DNA: This accurately describes the key activities during interphase. - **d.** Mitosis proceeds: Mitosis happens after interphase is complete.

Step 4: Selecting the Correct Option

The option that accurately describes what occurs during interphase is **c. a cell grows and duplicates its DNA**. This answer aligns with the activities observed during the interphase phase of the cell cycle.

Key Concepts

Interphase

Interphase is a crucial phase of the cell cycle where preparation for division takes place. Unlike mitosis, where actual cell division occurs, interphase is all about getting ready. Think of it as the planning stage before building starts. During this time, cells are highly active:

• They increase in size, making room for new cellular structures.
• Interphase consists of three stages: G1 (cell growth), S (DNA replication), and G2 (final preparations for mitosis).

While not as dramatic as mitosis, interphase is essential, ensuring that the cell is healthy and capable of dividing successfully. Cells accomplish several critical functions during interphase, including increased metabolic activity, the repair of DNA damage, and preparation for the physical demands of mitosis. These activities are crucial for maintaining proper cellular function.

DNA Replication

During the S phase of interphase, the cell replicates its DNA, ensuring that each new cell will have a complete set of genetic instructions. DNA replication is a highly regulated process that guarantees the fidelity of genetic information transfer.

• DNA unwinds from its coiled structure, with enzymes like helicase opening the double helix.
• New strands are synthesized by DNA polymerase, adding nucleotides complementary to the original strand, ensuring a perfect match.

This process is vital because, without accurate DNA replication, cells would become genetically unstable. Mistakes could lead to mutations, potentially causing diseases. However, the cell has mechanisms to correct errors, maintaining genetic integrity.

Cell Growth

Cell growth is a significant activity during the G1 and G2 phases of interphase. It plays a vital role in preparing the cell for division. During G1, the cell increases its supply of proteins and organelles, growing in size to accommodate future division.

• Cells synthesize necessary biomolecules, like proteins, lipids, and carbohydrates.
• The increased size allows distribution of sufficient cellular material between daughter cells.

In G2, additional growth can occur as the cell checks for be-all systems go status before proceeding to mitosis. This check-up ensures that everything is in place for successful division. Both size and content must be adequate for when the cell splits into two, ensuring that the new cells are functional and ready to perform their role in the organism.