Phases of Mitosis - Mastery Review Graphic Organizer - Free Printable

The task involves identifying the phases of mitosis based on the provided diagrams and explaining what is happening in each phase. Let's analyze each diagram step by step:

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Diagram 1:

- Phase: Prophase
- What is happening?
- The nuclear envelope begins to break down.
- Chromosomes condense and become visible.
- Centrioles (in animal cells) move to opposite poles of the cell, forming the spindle fibers.

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Diagram 2:

- Phase: Metaphase
- What is happening?
- Chromosomes align at the metaphase plate (the equatorial plane of the cell).
- Spindle fibers attach to the kinetochores of the chromosomes, ensuring proper alignment for separation.

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Diagram 3:

- Phase: Anaphase
- What is happening?
- Sister chromatids are pulled apart by the spindle fibers.
- Each chromatid moves toward opposite poles of the cell.
- This ensures that each daughter cell will receive one copy of each chromosome.

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Diagram 4:

- Phase: Telophase
- What is happening?
- Chromosomes reach the opposite poles of the cell and begin to decondense.
- The nuclear envelope reforms around each set of chromosomes.
- Spindle fibers disassemble.

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Final Answer:

| PHASE | WHAT IS HAPPENING? |
|---------------|---------------------------------------------------------------------------------------|
| Prophase | Nuclear envelope breaks down; chromosomes condense; centrioles move to opposite poles. |
| Metaphase | Chromosomes align at the metaphase plate; spindle fibers attach to kinetochores. |
| Anaphase | Sister chromatids are pulled apart by spindle fibers; each moves to opposite poles. |
| Telophase | Chromosomes reach opposite poles; nuclear envelope reforms; spindle fibers disassemble. |

Boxed Final Answer:
\[
\boxed{
\begin{array}{|c|l|}
\hline
\text{Prophase} & \text{Nuclear envelope breaks down; chromosomes condense; centrioles move to opposite poles.} \\
\hline
\text{Metaphase} & \text{Chromosomes align at the metaphase plate; spindle fibers attach to kinetochores.} \\
\hline
\text{Anaphase} & \text{Sister chromatids are pulled apart by spindle fibers; each moves to opposite poles.} \\
\hline
\text{Telophase} & \text{Chromosomes reach opposite poles; nuclear envelope reforms; spindle fibers disassemble.} \\
\hline
\end{array}
}
\]