A cell examined during prophase of cell cycle contained 100 units of DNA and 50 chromosomes. What would be the number of DNA and chromosome in anaphase of this cell cycle?

Options

A. 200 DNA & 100 chromosomes
B. 100 DNA & 50 chromosomes
C. 100 DNA & 100 chromosomes
D. 50 DNA & 25 chromosomes

Answer

To solve the question regarding the number of DNA units and chromosomes in anaphase, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Initial Conditions**:
- During prophase, the cell contains 100 units of DNA and 50 chromosomes.

2. **Understand the Cell Cycle Phases**:
- The cell cycle includes interphase (where DNA is replicated) and mitotic phase (M phase), which includes prophase, metaphase, anaphase, and telophase.
- During interphase, specifically in the S phase, DNA replication occurs, resulting in duplicated chromosomes.

3. **Determine DNA Content in Anaphase**:
- In prophase, the DNA content is represented as 2C (where C is the amount of DNA in a haploid set).
- By the time the cell reaches anaphase, the DNA content remains the same as it was in prophase because DNA replication occurs during the S phase, before prophase.
- Therefore, the DNA content in anaphase is still 100 units.

4. **Determine Chromosome Count in Anaphase**:
- In prophase, the chromosome count is represented as 2N (where N is the number of chromosomes in a haploid set).
- During anaphase, the sister chromatids are pulled apart, effectively doubling the number of chromosomes counted.
- Since there were 50 chromosomes in prophase (2N), in anaphase, the number of chromosomes will be 100 (as each chromosome splits into two).

5. **Final Answer**:
- Thus, in anaphase, the number of DNA units remains 100, and the number of chromosomes becomes 100.

### Summary:
- **DNA in Anaphase**: 100 units
- **Chromosomes in Anaphase**: 100 chromosomes