HANDOUT - Cell Cycle Review.docx - WLHS/Biology Name: THE CELL ... - Free Printable

Problem Analysis:

The image provided is a worksheet titled "The Cell Cycle Worksheet." The task involves identifying and labeling different stages of the cell cycle, as well as answering questions related to the cell cycle. Below is a detailed explanation of the solution for each part of the worksheet.

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Part A: Label the Stages

#### Instructions:
Label the stages of the cell cycle in the diagram below.

#### Solution:
The cell cycle consists of two main phases: Interphase and Mitosis (M Phase). Interphase is further divided into three sub-phases: G1, S, and G2. Mitosis is typically divided into four stages: Prophase, Metaphase, Anaphase, and Telophase. Additionally, there is a stage called Cytokinesis, which occurs after Telophase.

Here is how the stages should be labeled:

1. G1 Phase: This is the first gap phase where the cell grows and prepares for DNA replication.
2. S Phase: During this phase, DNA replication occurs.
3. G2 Phase: This is the second gap phase where the cell continues to grow and prepares for mitosis.
4. Prophase: Chromosomes condense, the nuclear envelope breaks down, and the mitotic spindle begins to form.
5. Metaphase: Chromosomes align at the metaphase plate (equatorial plane) with their kinetochores attached to spindle fibers.
6. Anaphase: Sister chromatids separate and are pulled toward opposite poles of the cell.
7. Telophase: Chromosomes decondense, the nuclear envelope reforms, and the cell begins to divide.
8. Cytokinesis: The cytoplasm divides, resulting in two daughter cells.

If the diagram shows these stages, label them accordingly.

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Part B: Answer the Questions

#### Question 1:
What is the purpose of the cell cycle?

#### Solution:
The purpose of the cell cycle is to ensure that a cell accurately duplicates its genetic material (DNA) and distributes it equally to two daughter cells during cell division. This process is essential for growth, development, tissue repair, and asexual reproduction in organisms.

#### Question 2:
Which phase of the cell cycle is the longest?

#### Solution:
The G1 phase is generally the longest phase of the cell cycle. During G1, the cell grows in size, synthesizes proteins and organelles, and performs various metabolic activities. It also checks whether conditions are favorable for DNA replication before entering the S phase.

#### Question 3:
What happens during the S phase?

#### Solution:
During the S phase (Synthesis phase), the cell replicates its DNA. Each chromosome is duplicated, resulting in two identical sister chromatids joined at the centromere. This ensures that each daughter cell will receive an exact copy of the genetic material.

#### Question 4:
Why is cytokinesis important?

#### Solution:
Cytokinesis is the final stage of the cell cycle where the cytoplasm of the parent cell divides, resulting in two separate daughter cells. It is crucial because it physically separates the genetic material and cellular components into two distinct cells, completing the process of cell division. Without cytokinesis, the cell would not split into two independent daughter cells, and the cell cycle would not be complete.

#### Question 5:
If a cell spends 10 hours in G1, 6 hours in S, and 4 hours in G2, how long is the entire interphase?

#### Solution:
Interphase consists of the G1, S, and G2 phases. To find the total duration of interphase, add the times spent in each phase:

\[
\text{Total Interphase} = \text{G1} + \text{S} + \text{G2}
\]
\[
\text{Total Interphase} = 10 \, \text{hours} + 6 \, \text{hours} + 4 \, \text{hours} = 20 \, \text{hours}
\]

Thus, the entire interphase lasts 20 hours.

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Final Answers:

1. Purpose of the cell cycle: To ensure accurate duplication and distribution of genetic material during cell division.
2. Longest phase: G1 phase.
3. S phase: DNA replication occurs.
4. Importance of cytokinesis: It physically separates the cell into two daughter cells, completing the cell division process.
5. Duration of interphase: 20 hours.

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Final Boxed Answer:

\[
\boxed{20 \, \text{hours}}
\]