In the testes of a healthy male mammal, spermatogenic cells undergo mitotic division to maintain the stem cell line (spermatogonia), or meiotic division to produce haploid spermatids.
A diploid spermatogonium in the G1 phase of interphase has a DNA content of 6.0 pg6.0\text{ pg}6.0 pg.
The following diagram illustrates how the DNA mass per cell (in picograms, pg\text{pg}pg) changes over time through these cell divisions:
Based on this information and the patterns of cell division, consider these four potential sequences describing the DNA content per cell at successive stages (from G1 of the parent cell, through any replication phase, to the completion of the respective division or divisions):
- Sequence I: 6.0 pg→12.0 pg→6.0 pg6.0\text{ pg} \to 12.0\text{ pg} \to 6.0\text{ pg}6.0 pg→12.0 pg→6.0 pg
- Sequence II: 6.0 pg→12.0 pg→6.0 pg→3.0 pg6.0\text{ pg} \to 12.0\text{ pg} \to 6.0\text{ pg} \to 3.0\text{ pg}6.0 pg→12.0 pg→6.0 pg→3.0 pg
- Sequence III: 12.0 pg→6.0 pg→3.0 pg12.0\text{ pg} \to 6.0\text{ pg} \to 3.0\text{ pg}12.0 pg→6.0 pg→3.0 pg
- Sequence IV: 6.0 pg→6.0 pg→3.0 pg6.0\text{ pg} \to 6.0\text{ pg} \to 3.0\text{ pg}6.0 pg→6.0 pg→3.0 pg
Which of the following correctly identifies the sequences for mitosis and meiosis in these cells?
Mitosis: Sequence I; Meiosis: Sequence III
Mitosis: Sequence II; Meiosis: Sequence I
Mitosis: Sequence I; Meiosis: Sequence II
Mitosis: Sequence IV; Meiosis: Sequence III