MCAT® ExamBiological and Biochemical Foundations of Living SystemsEasy
A cellular biologist observes a eukaryotic cell undergoing a process where chromatin condenses, the nuclear envelope breaks down, and spindle fibers begin to form. This cell is most likely in which phase of mitosis?
- AMetaphase
- BTelophase
- CAnaphase
- DProphase
Show answer & explanationAnswer & explanation
Correct answer: D. Prophase
These events—chromatin condensation, nuclear envelope breakdown, and spindle formation—are characteristic hallmarks of prophase, the first stage of mitosis.
Why the other options are wrong
- A. Metaphase involves chromosomes aligning at the metaphase plate.
- B. Telophase involves chromosomes decondensing, nuclear envelopes reforming, and cytokinesis beginning.
- C. Anaphase involves sister chromatids separating and moving to opposite poles.
Mitotic Prophase
The first stage of mitosis, characterized by the condensation of chromatin into visible chromosomes, breakdown of the nuclear envelope, and formation of the mitotic spindle.
- Chromosomes become visible under a light microscope.
- Centrosomes move to opposite poles.
- Initiates the precise segregation of genetic material.
Memory trick: PMAT: Prophase prepares, Metaphase meets, Anaphase apart, Telophase terminates.