CELLs alive! - Cell Cycle Worksheet illustrating the stages of the cell cycle with descriptive text.

This worksheet is asking you to match the numbered descriptions (1–10) with the correct phase or checkpoint of the cell cycle, based on the diagram and your knowledge of cell biology.

Let’s go step by step to solve this.

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🔁 The Cell Cycle Phases (in order):

The main phases of the cell cycle are:

1. G₁ Phase – Gap 1: Cell grows, synthesizes RNA/proteins, prepares for DNA replication.
2. S Phase – Synthesis: DNA replication occurs.
3. G₂ Phase – Gap 2: Cell grows more, checks DNA integrity, prepares for mitosis.
4. M Phase – Mitosis: Cell divides its nucleus and cytoplasm → two daughter cells.
5. G₀ Phase – Resting state: Cell is not actively preparing to divide; can be temporary or permanent.

There are also checkpoints:
- G₁/S checkpoint – Decides if cell enters S phase.
- G₂/M checkpoint – Ensures DNA is replicated and undamaged before mitosis.
- M checkpoint (Spindle Assembly Checkpoint) – Ensures chromosomes are properly attached to spindle before anaphase.

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## ✔ Matching Each Statement to the Correct Phase/Checkpoint

Let’s match each numbered description to the correct part of the diagram:

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1.) The cells increase in size and produces RNA and synthesize protein. It ensures that cells are ready for DNA Synthesis.

→ This describes G₁ Phase (Gap 1).
✔ Answer: G₁

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2.) Cell may remain metabolically active but quit dividing in Go. This stage can be temporary or permanent.

→ This is describing G₀ Phase (resting state).
✔ Answer: G₀

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3.) Cells decides whether to proceed S Phase (DNA Synthesis) or not.

→ This is the G₁/S checkpoint — the decision point before entering S phase.
✔ Answer: G₁/S checkpoint

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4.) The cell passes through the G2 checkpoint, it then proceeds to S phase.

⚠️ Wait — this is incorrect!
After G₂, the cell proceeds to M phase, NOT S phase. S phase comes *before* G₂.

This might be a typo in the worksheet. But based on context, it likely means:
> “The cell passes through the G₁ checkpoint, it then proceeds to S phase.”
OR
> “The cell passes through the G₂ checkpoint, it then proceeds to M phase.”

But since it says “proceeds to S phase”, and S phase comes after G₁, this must refer to passing the G₁ checkpoint → entering S phase.

So we’ll assume it’s meant to say G₁ checkpoint → S phase.

✔ Answer: G₁ checkpoint

*(Note: If strictly following wording, this statement is biologically inaccurate — but in context, it’s referring to the G₁ checkpoint.)*

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5.) DNA replication takes place. After the DNA is copied, it then proceeds to G2.

→ This is clearly S Phase.
✔ Answer: S

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6.) This is where cells organize and condense the genetic materials and prepares to divide.

→ This describes events in Prophase of Mitosis (M Phase) — chromosomes condense, spindle forms.
✔ Answer: M Phase

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7.) G2 checkpoint ensures that all chromosomes have been replicated and DNA is not damaged before it enters mitosis.

→ This is the G₂/M checkpoint.
✔ Answer: G₂/M checkpoint

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8.) Resting state

→ This is G₀ Phase.
✔ Answer: G₀

*(Note: #2 also described G₀ — so both 2 and 8 point to G₀. That’s fine — different descriptions of same phase.)*

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9.) M checkpoint ensures that all cell is ready to complete cell division.

→ This is the M checkpoint (Spindle Assembly Checkpoint) — occurs during metaphase to ensure chromosomes are aligned.
✔ Answer: M checkpoint

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10.) This is where the cell actually partitions the two copies of the genetic material into the two daughter cells.

→ This is Mitosis (M Phase) — specifically, anaphase/telophase/cytokinesis.
✔ Answer: M Phase

*(Note: #6 also points to M Phase — again, different aspects of the same phase.)*

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## 🧩 Final Answer Key (Matching Numbers to Phases/Checkpoints)

| Number | Description | Answer |
|--------|-----------------------------------------------------------------------------|---------------------|
| 1 | Cell grows, makes RNA/protein → ready for DNA synthesis | G₁ |
| 2 | Metabolically active but not dividing → G₀ | G₀ |
| 3 | Decides whether to enter S phase | G₁/S checkpoint |
| 4 | Passes checkpoint → proceeds to S phase *(assumed G₁ checkpoint)* | G₁ checkpoint |
| 5 | DNA replication → proceeds to G₂ | S |
| 6 | Organizes/condenses genetic material → prepares to divide | M Phase |
| 7 | G₂ checkpoint → checks DNA replication & damage before mitosis | G₂/M checkpoint |
| 8 | Resting state | G₀ |
| 9 | M checkpoint → ensures readiness to complete division | M checkpoint |
| 10 | Partitions genetic material into two daughter cells | M Phase |

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## 📌 Summary of Diagram Labels (for reference):

- Purple arc: G₀
- Yellow arc: G₁
- Blue arc: S
- Green arc: G₂
- Red arc: M
- Arrows pointing to checkpoints: G₁/S, G₂/M, M checkpoint

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## 💡 Teaching Tip:

This worksheet reinforces understanding of:
- The sequence of the cell cycle.
- The purpose of each phase.
- The role of checkpoints in ensuring fidelity of division.
- The difference between phases and checkpoints.

If you’re using this for study, try drawing the cycle yourself and labeling each part with its function!

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✔ You’ve now solved the worksheet! Let me know if you’d like a labeled diagram or flashcards for review.