Download The Cell Cycle

The Cell Cycle
Textbook pages 244 – 252
Introduction:
The cell cycle is a continuous cycle of growth and division in which eukaryotic cells reproduce. In
unicellular organisms like the amoeba and paramecium, cell division is the primary means of asexual
reproduction, but in multicellular organisms, cell division allows for growth.
Humans have two basic types of cells, somatic cells and reproductive sex cells called gametes. The main
difference in these types of the cells is the number of chromosomes. Human somatic cells, also called "body"
cells have 46 chromosomes or 23 pairs. The gametes (egg and sperm) only have 23 chromosomes. The number
of chromosomes in the gametes is "half" that of the somatic cells. The main reason is because the sex cells are
used for sexual reproduction. The number of chromosomes in the gametes is referred to as "haploid" while the
"diploid" number is 46. When egg and sperm come together during sexual reproduction, they fuse to form a
zygote. The zygote is a single cell with 46 chromosomes, 23 from the egg and 23 from the sperm. After
fertilization, the zygote will begin to divide through the process of mitosis. A human somatic cell takes
approximately 22 hours to divide. The division process called the Cell Cycle is divided into 3 parts:
Interphase, Mitosis and Cytokinesis. The original cell is called the "parent cell." The resulting cells after
division has taken place are called "daughter cells." Other than size, the daughter cells are identical to the
parent cell as well as identical to each other.
Procedure: In this activity, you will create a foldable that illustrates each stage of the cell cycle.
1. Fold your sheet with the phase of the Cell Cycle in half so the diagrams are in the left side on the inside.
2. On the outside, LABEL each phase of the Cell Cycle
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
* Use COLOR to distinguish between the 3 parts of the cell cycle: Interphase, Mitosis and Cytokinesis
3. DRAW and LABEL a double-stranded chromosome in the prophase section next to the diagram.
- sister chromatids
- centromere
4. In each diagram, color each structure the color indicated below IF it is present.
5. LABEL each of the structures in the phase indicated below.
Ex: The nuclear envelope is visible during Interphase, Prophase, Telophase and Cytokinesis, so it
should be colored in all four phases….BUT should only be labeled in Interphase & Telophase.
Structure
Plasma Membrane (Parent Cell)
Nuclear Envelope
Nucleolus
Chromatin
Centrioles
Spindle Fibers
Sister Chromatids
Centromere
Plasma Membrane (Daughter Cells)
Color
Purple
Red
Black
Blue
Yellow
Orange
Blue
Black
Green
Only LABEL it in ….
Interphase
Interphase & Telophase
Interphase & Cytokinesis
Interphase & Telophase
Metaphase
Metaphase
Prophase
Prophase
Telophase & Cytokinesis
6. For each event listed, determine which of the 6 stages of the Cell Cycle it occurs and then write
a I, P, M, A, T or C beside it.
Example:  I
Longest stage of the Cell Cycle
They are not in the order in which they occur. Use pages 246 – 252 of your textbook.

Nuclear envelope disappears.

DNA is in the form of chromatin. No chromosomes are visible.

Spindle fibers stretch across the cell to form a spindle apparatus.
 I
Longest stage of the Cell Cycle

Cytoplasm is divided between the two daughter cells.
 ___ Shortest phase of Mitosis

Double stranded chromosomes line up along the equator of the cell.

Nuclear envelope reforms around each new set of chromosomes.

DNA replicates, doubling the number of chromosomes from 46 to 92.

Sister chromatids are separated at the centromere.
 ___ Nucleolus disappears.

Chromosomes uncoil to form chromatin.

Chromosomes begin to move to opposite poles of the cell.

Spindle apparatus is disassembled.
 ___ Longest phase of Mitosis

In plant cells, the cell plate forms between the daughter cells.

Proteins that make microtubules (spindle fibers) are assembled.

Chromatin condenses into chromosomes.

Cell growth is rapid as the cell doubles all the contents of the cell.

Centrioles move to opposite sides (poles) of the cell.
7. Once you have determined which stage of the cell cycle each step belongs, write them on the right side of
the inside your foldable. Make sure the steps are IN ORDER for each phase.
8. Answer the Analysis Questions.
DOUBLE CHECK
Make sure you have DRAWN, COLORED & LABELED everything as
indicated in the directions #2 - #5.
-
Longest stage of the cell cycle
The Cell Cycle
Name:
Date: 3/7/2017
Block: 4A
Analysis Questions: Use the Introduction and Sections 9-2 & 9-3 in the textbook to answer the following
questions.
1. What are the two main types of cells in most organisms?
2. How do somatic cells differ from gametes?
3. How many chromosomes are in a human somatic cell?
4. How many chromosomes are in a human gamete?
5. When two gametes fuse, what is the new cell called?
6. For each of the following, indicate what phase of Interphase that each occurs, G1, S or G2. (pg 247)
Cell makes copies (replicates) it’s DNA
Cell prepares for nuclear division
Period of normal growth
Cell takes inventory of contents of the cell.
Cell carries out normal functions.
7. LABEL the diagram of the cell cycle with the following:
Metaphase
Synthesis (S)
Anaphase
Interphase
Cytokinesis
Gap 1 (G1)
Telophase
Mitosis
Prophase
Gap 2 (G2)
8. The division of the chromosomes between the new cells is called
9. Because prokaryotes don’t have a nucleus, they divide in a process called
(pg 247)
. (pg 246, 247, 248)
10. What 3 things make up the spindle apparatus? (pg 250)
11. What two molecules control activities in the cell cycle? (pg 253)
a.
b.
12. Describe four activities that are controlled by cyclin/CDK. (pg 253, Fig 9.11)
a.
b.
c.
d.
13. When do the checkpoints occur in the cell cycle? See pages 253-254.
Checkpoint
When does it occur?
1
2
3
4
14. Why are the checkpoints important? (pg 254)
15. What can happen if a cell divides uncontrollably? (pg 254)
16. What is apoptosis?(pg. 256)
How is it beneficial? (pg. 256)
16. What are stem cells?
17. What are the two types of stem cells? (pg. 256 – 257)
a.
b.
18. Give 3 Benefits of Stem Cell Research (pg. 258)
a.
b.
c.
What is checked?