AP Biology Questions on Prophase and Chromosome Condensation

🧬 Quick Study Guide

• 🔬 Prophase is the first stage of mitosis and meiosis. It follows interphase.
• 📚 During prophase, chromatin condenses into visible chromosomes. This makes it easier to separate them later.
• 🌀 Each chromosome consists of two identical sister chromatids joined at the centromere.
• 🌟 The nuclear envelope breaks down during prophase, and the spindle fibers begin to form.
• 🧵 Spindle fibers attach to the kinetochores of the chromosomes, preparing them for separation.
• 🧮 Chromosome condensation involves supercoiling of DNA, reducing the chromosome length significantly.
• 🧪 Condensin proteins play a crucial role in chromosome condensation.

🧪 Practice Quiz

1. Which of the following events occurs during prophase?

   1. DNA replication
   2. Chromosome decondensation
   3. Nuclear envelope breakdown
   4. Cytokinesis

2. What is the primary function of chromosome condensation during prophase?

   1. To increase the rate of DNA replication
   2. To facilitate chromosome segregation
   3. To initiate transcription
   4. To protect the DNA from damage

3. Which structure holds sister chromatids together during prophase?

   1. Centrosome
   2. Kinetochore
   3. Centromere
   4. Spindle fiber

4. What protein complex is primarily responsible for chromosome condensation?

   1. Histone
   2. Condensin
   3. Cohesin
   4. Actin

5. During which phase does the nuclear envelope disappear?

   1. Interphase
   2. Prophase
   3. Metaphase
   4. Anaphase

6. What is the role of spindle fibers during prophase?

   1. To replicate DNA
   2. To degrade the nuclear envelope
   3. To attach to chromosomes
   4. To synthesize proteins

7. Which of the following best describes the state of chromosomes during prophase?

   1. Unreplicated and decondensed
   2. Replicated and decondensed
   3. Unreplicated and condensed
   4. Replicated and condensed