Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in
a. G1
b. G2
c. Prophase
d. Metaphase

Verified step by step guidance

1. Understand the cell cycle phases: The cell cycle consists of interphase (G1, S, G2) and mitosis (prophase, metaphase, anaphase, telophase). During interphase, the cell grows and duplicates its DNA.
2. Identify DNA content in each phase: In G1 phase, the cell has a single set of DNA. During S phase, DNA replication occurs, doubling the DNA content. In G2 phase, the cell has twice the DNA content as in G1. During mitosis, the DNA content remains doubled until cytokinesis.
3. Analyze the given information: Cell A has half the DNA content compared to cells B, C, and D. This suggests that Cell A has not yet undergone DNA replication.
4. Determine the phase of Cell A: Since Cell A has half the DNA content, it is likely in the G1 phase, where the DNA has not yet been replicated.
5. Conclude the reasoning: Based on the DNA content, Cell A is most likely in the G1 phase, as it has not yet entered the S phase where DNA replication occurs.

Key Concepts

Cell Cycle Phases

The cell cycle consists of distinct phases: G1, S, G2, and M. G1 is the first gap phase where the cell grows and prepares for DNA replication. S phase is where DNA replication occurs, doubling the DNA content. G2 is the second gap phase, where the cell prepares for mitosis. M phase includes mitosis and cytokinesis, where the cell divides into two daughter cells.

DNA Content During Cell Cycle

DNA content varies throughout the cell cycle. In G1, cells have a normal diploid amount of DNA. During S phase, DNA is replicated, doubling the DNA content. In G2, cells maintain this doubled DNA content until mitosis, where the DNA is equally divided between two daughter cells. Understanding DNA content helps identify the cell cycle phase.

Mitosis Stages

Mitosis is divided into stages: prophase, metaphase, anaphase, and telophase. Prophase involves chromatin condensation into visible chromosomes. Metaphase is characterized by chromosomes aligning at the cell's equatorial plane. Anaphase involves the separation of sister chromatids, and telophase concludes with the formation of two nuclei. DNA content remains doubled until cytokinesis.