Study aid showing the phases of mitosis in an animal cell, from interphase to the formation of two daughter cells.

Problem Overview:

The task involves analyzing the stages of mitosis in an animal cell and answering questions about the changes that occur during each stage. The diagrams provided show the cell before, during, and after mitosis.

Solution:

#### BEFORE MITOSIS: Interphase
1. Label the cell membrane, cytoplasm, nucleus, and chromosomes.
- Cell membrane (1): The outer boundary of the cell.
- Cytoplasm (2): The gel-like substance inside the cell, surrounding the nucleus.
- Nucleus (3): The central organelle containing genetic material.
- Chromosomes (4): Visible as thin, thread-like structures within the nucleus.

2. How many chromosomes are present?
- In the diagram, there appear to be 4 chromosomes. This is a simplified representation; in real cells, the number varies depending on the species.

3. In prophase, what has happened to the chromosomes since interphase?
- During prophase, the chromosomes condense and become more visible. They coil tightly, making them shorter and thicker. The nuclear envelope begins to break down, and the nucleolus disappears.

#### MITOSIS, Stage 1: Prophase
4. Describe any new structure that has formed.
- During prophase, the spindle fibers begin to form. These fibers will eventually help separate the chromosomes into two daughter cells.

#### MITOSIS, Stage 2: Metaphase
5. In metaphase, what has happened to the nucleus?
- The nuclear envelope has completely broken down, and the chromosomes are no longer contained within the nucleus.

6. How have the arrangement and the location of the chromosomes changed?
- The chromosomes align at the metaphase plate (the equatorial plane of the cell). Each chromosome is attached to spindle fibers at its centromere, ensuring they are evenly positioned for separation.

#### MITOSIS, Stage 3: Anaphase
7. In anaphase, how have the chromosomes changed since metaphase?
- During anaphase, the sister chromatids (halves of each chromosome) are pulled apart by the spindle fibers. They move toward opposite poles of the cell, ensuring that each pole receives one complete set of chromosomes.

#### MITOSIS, Stage 4: Telophase
8. In telophase, how have the location and arrangement of the chromosomes changed?
- In telophase, the chromosomes reach the opposite poles of the cell. The nuclear envelope begins to reform around each set of chromosomes, and the chromosomes start to uncoil, becoming less visible. The spindle fibers disassemble.

#### AFTER MITOSIS: Two Daughter Cells
9. After mitosis and cell division are over, how are the two new cells similar to the original cell in interphase?
- The two daughter cells are genetically identical to the original cell. Each daughter cell contains the same number and type of chromosomes as the original cell. They also have the same cellular components (cell membrane, cytoplasm, etc.) and are ready to enter interphase and grow before undergoing another round of mitosis if necessary.

Final Answers:

1. Labels:
- Cell membrane (1)
- Cytoplasm (2)
- Nucleus (3)
- Chromosomes (4)

2. Number of chromosomes: 4

3. Prophase change in chromosomes: Chromosomes condense and become visible; the nuclear envelope breaks down.

4. New structure in prophase: Spindle fibers form.

5. Metaphase change in nucleus: The nuclear envelope has completely broken down.

6. Metaphase arrangement of chromosomes: Chromosomes align at the metaphase plate, attached to spindle fibers.

7. Anaphase change in chromosomes: Sister chromatids are separated and pulled to opposite poles.

8. Telophase change in chromosomes: Chromosomes reach opposite poles; the nuclear envelope reforms, and chromosomes uncoil.

9. Similarities between daughter cells and original cell: Genetically identical, same number and type of chromosomes, and same cellular components.

Final Answer Box:

\[
\boxed{
\begin{array}{l}
\text{1. Labels: Cell membrane (1), Cytoplasm (2), Nucleus (3), Chromosomes (4)} \\
\text{2. Number of chromosomes: 4} \\
\text{3. Prophase change in chromosomes: Condense and become visible; nuclear envelope breaks down} \\
\text{4. New structure in prophase: Spindle fibers form} \\
\text{5. Metaphase change in nucleus: Nuclear envelope breaks down} \\
\text{6. Metaphase arrangement of chromosomes: Align at metaphase plate, attached to spindle fibers} \\
\text{7. Anaphase change in chromosomes: Sister chromatids are separated and pulled to opposite poles} \\
\text{8. Telophase change in chromosomes: Reach opposite poles; nuclear envelope reforms, chromosomes uncoil} \\
\text{9. Similarities between daughter cells and original cell: Genetically identical, same chromosomes, same components}
\end{array}
}
\]