One event occurring during prophase is __________.

• A. the synthesis of a new nuclear envelope
• B. the alignment of chromosomes in a single plane
• C. cytokinesis
• D. the division of the centromere
• E. the beginning of the formation of a spindle apparatus

Answer: (E)

Verified step by step guidance

1. Understand the phases of mitosis: Mitosis is divided into several stages, including prophase, metaphase, anaphase, and telophase. Each stage has distinct events that occur.
2. Identify the key events of prophase: During prophase, the chromatin condenses into visible chromosomes, and the nuclear envelope begins to break down. The spindle apparatus starts to form, which is crucial for chromosome movement.
3. Differentiate between the options: Analyze each option provided in the problem. The synthesis of a new nuclear envelope occurs during telophase, not prophase. The alignment of chromosomes in a single plane happens during metaphase. Cytokinesis is the division of the cytoplasm, occurring after mitosis. The division of the centromere occurs during anaphase.
4. Focus on the spindle apparatus: The formation of the spindle apparatus is a key event in prophase. It involves the assembly of microtubules that will eventually attach to chromosomes and help in their movement.
5. Conclude with the correct event: Based on the analysis, the beginning of the formation of a spindle apparatus is the correct event occurring during prophase.