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 problem, we need to understand the changes that occur in the number of DNA units and chromosomes during the different phases of the cell cycle, particularly focusing on prophase and anaphase.

### Step-by-Step Solution:

1. **Understanding Prophase**:
- In prophase, the cell has 50 chromosomes and 100 units of DNA.
- Each chromosome consists of two sister chromatids, which means that the total number of chromatids is equal to the number of DNA units. Therefore, each of the 50 chromosomes is made up of 2 chromatids.

2. **Chromosome and DNA Count in Prophase**:
- Number of chromosomes = 50
- Number of DNA units = 100 (since each chromatid represents one unit of DNA)

3. **Transition to Anaphase**:
- During anaphase, the sister chromatids of each chromosome are pulled apart and move towards opposite poles of the cell.
- As a result, the total number of chromosomes doubles because each chromatid is now considered an individual chromosome.

4. **Counting Chromosomes in Anaphase**:
- Since the 50 chromosomes split into 100 chromatids, the number of chromosomes in anaphase will be 100.

5. **Counting DNA in Anaphase**:
- The number of DNA units remains the same as in prophase because the DNA itself does not change; it is just the organization of the chromatids that changes.
- Therefore, the number of DNA units in anaphase will still be 100.

### Final Answer:
- Number of DNA in anaphase = 100
- Number of chromosomes in anaphase = 100

Thus, the correct answer is **100 DNA and 100 chromosomes**.