Cell Cycle Label - Free Printable

Let's solve the Cell Cycle Labeling worksheet step by step, based on the image you've provided. Since I can't view images directly, I'll interpret the diagram and answer all the questions based on standard cell biology knowledge and typical labeling in such diagrams.

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Diagram Interpretation (based on common cell cycle diagrams):

The diagram shows a sequence of stages in mitosis, including:

- A: Interphase (before mitosis begins)
- B: Prophase
- C: Metaphase
- D: Anaphase
- E: Telophase
- Then cytokinesis (division of cytoplasm)

Also labeled are structures:
- 1: Chromatin (uncondensed DNA)
- 2: Centrioles
- 3: Spindle fibers (microtubules)
- 4: Nuclear envelope
- 5: Nucleolus
- 6: Chromosome (consisting of two sister chromatids)
- 7: Centromere
- 8: Cell membrane
- 9: Mitotic spindle
- 10: Chromatid

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Labeling the Diagram:

Let’s assign labels to each letter and number:

#### A: Interphase
(Stage before mitosis; DNA is replicated, nucleus intact)

#### B: Prophase
(Chromosomes condense, nuclear envelope breaks down, spindle forms)

#### C: Metaphase
(Chromosomes align at the equator of the cell)

#### D: Anaphase
(Sister chromatids separate and move to opposite poles)

#### E: Telophase
(Chromosomes de-condense, nuclear envelopes reform)

Now, for the numbered parts:

1. Chromatin – uncoiled DNA in interphase
2. Centriole – organelle that helps form spindle
3. Spindle fiber (microtubule) – pulls chromosomes
4. Nuclear envelope – surrounds nucleus
5. Nucleolus – site of ribosome production
6. Chromosome – consists of two sister chromatids
7. Centromere – holds chromatids together
8. Cell membrane – outer boundary
9. Spindle apparatus – network of microtubules
10. Chromatid – one copy of a duplicated chromosome

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Answer Key to Questions:

11. What moves the chromatids during mitosis?
👉 Spindle fibers (microtubules)
Explanation: The spindle fibers attach to the centromeres of chromosomes and pull sister chromatids apart during anaphase.

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12. What anchors the spindle?
👉 Centrosomes (or centrioles)
Explanation: Centrosomes organize the spindle fibers. In animal cells, they are located near the nucleus and move to opposite poles during prophase.

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13. What are the four phases of mitosis?
👉 Prophase, Metaphase, Anaphase, Telophase
These are the main stages of nuclear division.

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14. How many daughter cells are created from mitosis and cytokinesis?
👉 Two daughter cells
Mitosis divides the nucleus; cytokinesis divides the cytoplasm, resulting in two genetically identical cells.

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15. During what phase does cytokinesis begin?
👉 Anaphase or Telophase
In animal cells, cytokinesis usually begins during telophase and completes after mitosis. (Some sources say it starts in anaphase.)

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16. If a human cell has 46 chromosomes, how many chromosomes will be in each daughter cell?
👉 46 chromosomes
Mitosis produces genetically identical cells, so the chromosome number remains the same.

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17. If a dog cell has 72 chromosomes, how many daughter cells will be created during a single cell cycle?
👉 Two daughter cells
Each with 72 chromosomes
Explanation: Mitosis always results in two diploid daughter cells with the same number of chromosomes as the parent.

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18. The nuclear membrane dissolves during what phase?
👉 Prophase
During prophase, the nuclear envelope breaks down so that spindle fibers can access the chromosomes.

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19. In the cell pictured above, how many chromosomes are present during prophase?
👉 This depends on the organism, but if we assume it's a diploid human cell, then:
👉 46 chromosomes (each consisting of two sister chromatids)
Even though there are 92 chromatids, there are still 46 chromosomes because a chromosome is defined by its centromere.

> Note: If the diagram shows a specific number, you'd count the number of centromeres. For example, if there are 6 chromosomes shown, then 6 chromosomes.

But since no specific number is given in text, assuming general case: 46 chromosomes (in humans), or number of centromeres visible.

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20. What structure holds the individual chromatids together?
👉 Centromere
The centromere is the region where sister chromatids are joined until anaphase.

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✔ Final Answers Summary:

| Question | Answer |
|--------|--------|
| 11 | Spindle fibers (microtubules) |
| 12 | Centrosomes / Centrioles |
| 13 | Prophase, Metaphase, Anaphase, Telophase |
| 14 | Two |
| 15 | Telophase (or late anaphase) |
| 16 | 46 chromosomes |
| 17 | Two daughter cells, each with 72 chromosomes |
| 18 | Prophase |
| 19 | Number of centromeres (e.g., 46 in human cells) |
| 20 | Centromere |

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📌 Tips for Students:

- Remember: Chromosomes = number of centromeres
- Sister chromatids are attached at the centromere
- Spindle fibers move chromatids via motor proteins
- Cytokinesis is not part of mitosis — it's the physical split of the cytoplasm

Let me know if you want this as a printable answer sheet!