LifeSciTRC.org - Cells alive! - Cell Cycle Worksheet - Free Printable

The image you've uploaded is a "CELLS alive! - Cell Cycle Worksheet" that shows a diagram of the cell cycle, with labeled phases and arrows pointing to different parts of the cycle. The task is to identify what is happening at each numbered point (1 through 11) in the cell cycle.

Let’s go step-by-step to solve this worksheet.

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🔬 Understanding the Cell Cycle Diagram

The circular diagram represents the eukaryotic cell cycle, which includes:

1. Interphase – The phase where the cell grows and duplicates its DNA.
- Includes:
- G₁ phase: Cell growth
- S phase: DNA synthesis (replication)
- G₂ phase: Preparation for mitosis
2. M phase – Mitosis and cytokinesis
- Mitosis: Division of the nucleus
- Cytokinesis: Division of the cytoplasm
3. G₀ phase – A resting state where cells are not actively dividing

The diagram shows:
- Green: G₁
- Blue: S
- Yellow: G₂
- Red: M (mitosis)
- Purple: G₀ (optional, non-dividing state)

Arrows point to specific locations on the cycle, and we need to describe what's happening at each number.

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✔ Step-by-Step Answers

Here is the interpretation of each numbered label based on the standard cell cycle:

#### 1)
- Points to G₁ phase
- What's happening?
→ The cell is growing and carrying out normal functions. It prepares for DNA replication.

> Answer: Cell growth and preparation for DNA replication.

#### 2)
- Points to G₂ phase
- What's happening?
→ The cell is preparing for mitosis. It checks that DNA replication is complete and synthesizes proteins needed for division.

> Answer: Final preparations for cell division; checking DNA replication and protein synthesis.

#### 3)
- Points to M phase (mitosis)
- What's happening?
→ The nucleus divides (mitosis), followed by cytoplasmic division (cytokinesis).

> Answer: Nuclear division (mitosis) and cytoplasmic division (cytokinesis).

#### 4)
- Points to S phase
- What's happening?
→ DNA replication occurs. Each chromosome is duplicated into two sister chromatids.

> Answer: DNA replication; chromosomes are copied.

#### 5)
- Points to G₁ phase again (after cytokinesis)
- What's happening?
→ The daughter cells enter G₁ phase and begin growing.

> Answer: Daughter cells grow and prepare for next round of DNA replication.

#### 6)
- Points to interphase (specifically between G₁ and S)
- What's happening?
→ This is the transition from G₁ to S phase. The cell is still in interphase but moving toward DNA replication.

> Answer: Transition from G₁ to S phase; decision point (restriction point).

#### 7)
- Points to the beginning of mitosis (M phase)
- What's happening?
→ Chromosomes condense, nuclear envelope breaks down, spindle fibers form.

> Answer: Start of mitosis; chromosomes condense and spindle forms.

#### 8)
- Points to end of mitosis / cytokinesis
- What's happening?
→ Cytoplasm divides, forming two separate daughter cells.

> Answer: Cytokinesis; two daughter cells are formed.

#### 9)
- Points to G₀ phase
- What's happening?
→ The cell has exited the cycle and is not dividing. It may be performing specialized functions or resting.

> Answer: Cell is in a non-dividing state; may differentiate or remain dormant.

#### 10)
- Points to G₂ phase
- What's happening?
→ Same as #2 — final checks and preparations before mitosis.

> Answer: Preparing for mitosis; checking DNA integrity and producing necessary proteins.

#### 11)
- Points to G₁ phase (just before S phase)
- What's happening?
→ Cell is growing and assessing conditions to proceed into S phase.

> Answer: Cell growth and evaluation for entry into DNA synthesis.

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📝 Summary Table

| Number | Phase | What's Happening Now? |
|--------|-------------|------------------------|
| 1 | G₁ | Cell growth and preparation for DNA replication |
| 2 | G₂ | Final preparations for mitosis |
| 3 | M | Mitosis and cytokinesis |
| 4 | S | DNA replication |
| 5 | G₁ (post-M) | Daughter cells grow |
| 6 | G₁ → S | Transition point; decision to replicate DNA |
| 7 | M (start) | Chromosomes condense, spindle forms |
| 8 | Cytokinesis | Cytoplasm divides, two daughter cells form |
| 9 | G₀ | Cell exits cycle; not dividing |
| 10 | G₂ | Preparing for mitosis |
| 11 | G₁ | Growth and readiness for DNA synthesis |

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✔ Final Answer:

You should fill in the blanks on the worksheet as follows:

1. Cell growth and preparation for DNA replication
2. Final preparations for cell division
3. Nuclear and cytoplasmic division
4. DNA replication
5. Daughter cells grow
6. Transition from G₁ to S phase
7. Start of mitosis; chromosomes condense
8. Cytokinesis; formation of two daughter cells
9. Cell is in a non-dividing state (G₀)
10. Preparing for mitosis
11. Cell growth and evaluation before DNA synthesis

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