A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in a cell doubled a. between prophase and anaphase of mitosis. b. between the G1 and G2 phases of the cell cycle. c. during the M phase of the cell cycle. d. between prophase I and prophase II of meiosis.

Verified step by step guidance

1. Understand the context of the problem: The biochemist is measuring the amount of DNA in cells and observing when the DNA quantity doubles. This doubling occurs during DNA replication, which is a key event in the cell cycle.
2. Recall the phases of the cell cycle: The cell cycle consists of interphase (G1, S, and G2 phases) and the M phase (mitosis or meiosis). DNA replication occurs during the S phase (synthesis phase) of interphase, which is between the G1 and G2 phases.
3. Analyze the options: Option (a) refers to mitosis, where DNA is already replicated before prophase begins. Option (b) refers to the G1 and G2 phases, which are separated by the S phase where DNA replication occurs. Option (c) refers to the M phase, where DNA is divided but not replicated. Option (d) refers to meiosis, where DNA replication occurs before prophase I, not between prophase I and prophase II.
4. Focus on the correct phase: DNA doubling occurs during the S phase, which is part of interphase and specifically between the G1 and G2 phases. This matches option (b).
5. Conclude: The correct answer is that the DNA quantity doubles between the G1 and G2 phases of the cell cycle, as this is when DNA replication occurs during the S phase.

Key Concepts

Mitosis

Mitosis is the process of cell division that results in two genetically identical daughter cells from a single parent cell. It consists of several phases: prophase, metaphase, anaphase, and telophase. During mitosis, the DNA is replicated during the S phase of the cell cycle, and the actual separation of the duplicated chromosomes occurs during anaphase.

Cell Cycle

The cell cycle is a series of phases that a cell goes through to grow and divide. It includes the G1 phase (cell growth), S phase (DNA synthesis), G2 phase (preparation for mitosis), and M phase (mitosis and cytokinesis). The G1 to G2 transition is crucial for DNA replication, where the amount of DNA in the cell doubles in preparation for division.

Meiosis

Meiosis is a specialized form of cell division that reduces the chromosome number by half, resulting in four non-identical gametes. It consists of two rounds of division: meiosis I and meiosis II. During prophase I, homologous chromosomes pair and exchange genetic material, but the DNA does not double again between prophase I and prophase II, making it distinct from mitosis.