Cell Division, Cell Cycle, Mitosis, and Meiosis Webquest Name ______

Cell Division, Cell Cycle, Mitosis, and Meiosis WebQuest Name ______

Previous Knowledge:

1. How would you describe the process by which a unicellular organism increases its size?
2. Why do cells stay small?

Lesson Objectives:

Lesson Summary: Limits to Cell Size

There are two main reasons why cells divide: 1) either because of “information overload” or 2) because of material exchange issues. The larger a cell becomes, the more demands it puts on its DNA. A larger cell is inefficient in moving nutrients and waste products across the cell membrane. When a cell gets so large that it has put too many demands on its DNA, the cell has to divide. Cells also divide to resolve material exchange issues because cells need to take in nutrients and eliminate wastes through the cell membrane. As the cell gets larger, these processes become less efficient: the larger a cell’s volume, the more materials it needs to function and consequently, the more wastes it produces. If a cell’s volume increases at a faster rate than its surface area, its surface-area-to-volume ratio becomes too small; and the larger a cell gets, the harder it is for enough materials to move across its cell membrane. Cell division solves the information overload and materials exchange problems.

While waiting the 10 minutes in the activity, answer the following questions.

1. Describe “information overload” in your own words. ______

______

______

______

1. In the table below, calculate the Surface Area to Volume Ratio for each “cell”. Answer the questions below.

1. What are your observations? ______
2. What are the ratios comparing? ______
3. Which ratio is the best? Why? ______

Cell Division and Reproduction: Cell division is part of both types of reproduction.

 Asexual Reproduction:

• Produces genetically identical organisms
• Occurs in many single-celled organisms and in some multicellular organisms
• Allows rapid reproduction of organisms in favorable environments

 Sexual Reproduction:

• Produces organisms with genetic information from both parents
• Occurs in most animals and plants; and in many single-celled organisms
• Increases genetic diversity, which aids species survival in changing environments

Follow-up Questions: True or False: Correct the FALSE statements by changing words to make the statement TRUE.

______1. As a cell’s size increases, its amount of DNA increases.

______2. The amount of activity in a cell is related to its volume.

______3. The smaller the cell, the smaller its surface area to volume ratio.

______4. The information overload in a cell is solved by the replication of the DNA before cell division.

Prokaryotic Cell Division:

Go to the following sites to learn about prokaryote cells:

 Cells Alive

 Wikipedia: Binary Fission

1. Name three ways prokaryote cells differ from eukaryote cells (name characteristics of the prokaryote cells):

1. ______
2. ______
3. ______

2. Draw a prokaryote cell:

Prokaryote cells use a process called binary fission to divide. Go to the following site for the definition of binary fission: Binary Fission Definition

3. Binary fission is ______

Watch the animation on binary fission: Binary Fission Animation and click on “Prokaryotic Cell Division”

4. Describe what you saw in the animation. How does binary fission work: ______

______

______

______

Eukaryotic Cell Division:

There are several reasons for the cell to divide. Two reasons are shown at the following website:

Why Eukaryotic Cells Divide

5. Name the two reasons shown for cell division.

1. ______
2. ______

There are several parts of the cell involved in cell division. Click on the parts shown at the following site and read what they do. Parts of the Cell Involved in Cell Division

6. List the four organelles involved in cell division. What does each organelle do???

1. ______
2. ______
3. ______
4. ______

DNA can take many forms. When the cell is resting, it takes the form of chromatin. Look at chromatin in the following site: Chromatin Image

7. Describe the appearance of chromatin? ______

When the cell needs to divide, the DNA must coil up tightly into chromosomes. When DNA has not copied itself, the chromosomes will only have one strand. These strands are called chromatids. After DNA replicates, each strand (chromatid) has a twin that is attached to it. These pairs of twin chromatids are called sister chromatids. Sister chromatids are connected by a centromere. See what chromatids and sister chromatids look like on the following site: Chromatids & Their Sisters

8. Draw and label a picture of the sister chromatids and the centromere.

Stages of Mitosis: Go to the following website: Cells Alive: Mitosis

On the left side of the screen is a navigation bar, click on the link to “MITOSIS”. View the animation and read the text below the animation on this page.

9. List the stages of mitosis (Notice – there’s an extra phase here…”prometaphase” – sometimes that is added as an “in-between” phase between prophase and metaphase. In my class you are only responsible for knowing PMAT)

1. P______
2. M______
3. A______
4. T______

10. In which stage does each of the following occur???

 Chromatin condenses into chromosomes.

 Chromosomes align in center of the cell.

 Longest part of the cell cycle.

 Nuclear Envelope breaks down.

11. Identify the stages of mitosis in these cells:

a.______b.______c.______d. ______

Onion Root Tip - Online Lab Activity: Onion Root Tip Cell Cycle

 Read the introduction, then click the “next” button.

 Check out the different phases & read them & hit “next”.

 Read the “assignment” then hit “next”

 You will have 36 cells to classify. When you're finished, record your data in the chart below.

(Calculate percentage: number of cells divided by total cells x 100)

12. What do you notice about the stages from your calculations in the table?

13. What did you notice about the difference between Interphase & Prophase?

Cell Cycle Review: Use three (3) paper plates. On the bottom (1st) paper plate, define the “divisions” as seen in the illustration below. On the middle (2nd) paper plate, cut a “wedge” and identify each step in the cycle. On the top (3rd) paper plate, label the four (4) cell cycle phases. Attach the plates in the center with a brad.

Stages of Meiosis: Internet Investigation

Go to Stages of Meiosis Animation and watch the animation. Then click on the arrow to learn about meiosis.

1. What is the purpose of Meiosis and in what parts of the body does it occur???

______

1. With how many chromosomes does the cell in this animation begin? ______
2. The homologous pairs are represented by similar ______
3. Copies of chromosomes are held together by the ______
4. Each chromosome finds its ______
5. Draw “crossing over” – using your pencil to shade in the areas that exchange parts.

1. How many chromosomes are at each pole of the cell? ______
2. During meiosis 2, chromosomes line up again along the cell’s ______
3. Only ______copy of each chromosome moves toward the poles, which means only ______chromosomes of the original ______chromosomes.
4. New membranes form around each ______.
5. Each cell divides, forming a total of ______cells.

Mitosis vs. Meiosis:

1. Go to: Nova: How Cells Divide and Click on “How Cells Divide”. Read the Introduction and then click on “Mitosis vs. Meiosis”.
2. After viewing the animation. Fill out the chart below, by placing a check in the box or boxes.

1. Mitosis Game

1. Read the instructions on the web site and complete the activity asked.
2. When you have successfully completed the activity, you will see “You Win” and you can see the hidden picture. ((Notice – there’s an extra phase here...”prometaphase” – sometimes that is added as an “in-between” phase between prophase and metaphase. In my class you are only responsible for knowing IPMATC) EXPLAIN WHAT THE PICTURE IS: ______

1. Rags to Riches Game

1. Press “Start”!! Answer the questions to gain $$!!
2. Write down 10 questions and the correct answers for each of the 10 questions.
3. Attach the questions to this paper.

1. Overview of Mitosis

1. For an overview of what Mitosis looks like, go to the following site and watch the animation:
2. Write down the main events for each of the 6 main stages show in the animation.