Biology 2

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PRE-LAB EXERCISES

Open the A&P app, and from the left-side menu, select Cells and Tissue, and then choose Chapter
3. Cell Life Cycle.

Use the modules to guide your exploration of the life cycle of cells. Be sure to use the book icon to
learn more about the cellular concepts that you are exploring.

You are responsible for the identification of all bold terms and all answers to the questions.

A. DNA Replication and the Cell Cycle

1. Examine the illustration in Module 3.1 Replication to learn about the principles of DNA replication.
Use this module to answer the following questions.

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a. DNA is made of two long strands of nucleotides that form a double helix. The nucleotides in
each strand pair up with a specific complementary base on the other strand. In the following
illustration, examine a short piece of DNA, and based on the nucleotides that are labeled, fill in
the blank nucleotides.

b. When do cells copy their DNA?

2. Examine the illustration in Module 3.2 Cell Cycle and use it to match each of the following terms with
the correct description.

A= Adenine
T= Thymine
C= Cytosine
G= Guanine

A

AT

G

G

TC

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A. G0 Phase

B. G1 Phase

C. S Phase

D. G2 Phase

E. Interphase

F. Mitosis

G. Cytokinesis

_______ DNA replication, or synthesis, occurs during this phase.

_______ One cell splits into two cells during this phase.

_______ This phase is characterized by cell growth, organelle duplication, and protein synthesis.

_______ This phase includes all the phases except mitosis and cytokinesis.

_______ This phase includes a series of events that a cell undergoes leading up to cell division.

_______ This phase follows the S phase.

_______ In this phase, cells are not actively progressing through the cell cycle. These cells are
sometimes described as existing in a resting stage.

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IN-LAB EXERCISES

Use the following modules in Visible Body’s Anatomy & Physiology app to guide your exploration of
the cell cycle. Be sure to select the book icon under the structure name to read information specific
to that structure.

You are responsible for the identification of all bold terms and all answers to the questions.

Go to the Cells and Tissue unit and select Chapter 3. Cell Life Cycle.

A. Mitosis and Meiosis

1. Watch the video in Module 3.3 Mitosis and answer the following questions.

a. In which stage of mitosis do the chromosomes condense and organize into chromatid pairs?

b. In which stage of mitosis do the chromatid pairs line up along the cell’s midline?

c. In which stage of mitosis are the chromatid pairs pulled apart, each toward an opposite end of
the cell?

d. In which stage of mitosis does the nuclear membrane reform?

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2. Explore the 3D anatomical view in Module 3.4 Mitotic Spindle and answer the following questions.

a. The mitotic spindle is composed of a network of which cytoskeletal filaments?

b. Some types of chemotherapeutic drugs, used to treat cancer, disrupt microtubules and the
mitotic spindle. Why are drugs that disrupt the mitotic spindle effective cancer treatments?

Centrosome

Microtubules

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3. Examine the illustration in Module 3.5 Meiosis, comparing cells undergoing meiosis and mitosis, and
answer the following questions.

a. In humans, both meiosis and mitosis start with a cell that has __________duplicated
chromosomes. Remember, cells duplicate their DNA during S phase in the cell cycle; this
happens prior to meiosis or mitosis. Meiosis includes two rounds of cell division, whereas mitosis
only has one. As a result, cells that arise from meiosis have __________ chromosomes and cells
that arise from mitosis have __________ chromosomes.

b. What is the difference between a diploid cell and a haploid cell?

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4. Explore the 3D anatomical view in Module 3.6 Meiosis and Gametes and answer the following
questions.

1. Where does meiosis occur?

2. Why is mitosis incompatible with the production of sex cells, specifically, sperm and oocytes?

TIME TO PRACTICE!
GO TO THE QUIZZES MENU AND COMPLETE CELL LIFE CYCLE QUIZ 3.A.

Testes

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PUTTING IT ALL TOGETHER

In cellular physiology, there are almost always exceptions to the rules! Here are a few examples of rule
breakers in the world of the cell cycle.

1. During the first few days of human development, cell proliferation is very rapid, and as cells divide by
mitosis, the G1 and G2 phases are very short. How do you think this impacts cell size during this period
of development?

2. The cells in red bone marrow that produce blood platelets are called megakaryocytes, which can be
loosely translated as big nucleus cells. These cells continue to move through the cell cycle, but they
skip mitosis and cytokinesis. Review the steps of the cell cycle. What do you think the result of this
modified cell cycle would be?

3. Cell growth and progression through the cell cycle is a process that requires tight regulation. We
have specific genes that can inhibit the progression of a cell through the cell cycle. If these genes are
damaged through a mutation, what could be the consequence?

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Module 3.4 Mitotic Spindle

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Module 3.6 Meiosis and Gametes

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