CELL DIVISION: MAIN

Agenda: Last updated 05/03/04 -- This online tutorial teaches the basics of cell division. You will learn about the four stages of mitosis: prophase, metaphase, anaphase, and telophase. Images, defined words and other facts about cell division are also included. At the end, you can take a quick quiz to review what you learned.

CELL DIVISION: PROCESS

In mitosis, eukaryotic cell nuclei divide to form two nuclei, each containing a complete set of the cell's chromosomes. It undergoes many stages before it can divide. More detailed information is provided below.

DNA Replication
Chromosomes are not yet visible because they are extended and uncoiled. The DNA of each chromosome is copied. Each chromosome consists of two identical strands.

Prophase (considered to be the first stage of mitosis, 1 parent cell)
Mitosis begins. The chromosomes coil into short, fat rods. The nuclear envelope breaks up. A network of protein cables called spindle fibers assemble across the cell.

Since each daughter nucleus (the splitting cells) must receive a copy of each chromosome, DNA must replicate before mitosis can begin.

Metaphase
The nuclear membrane diminishes completely. Chromosomes attach to the spindle fibers and line up in the center of the cell.

Anaphase
Each chromatid separates from its identical copy. Chromosomes are pulled to opposite sides of the cell. The spindle fibers begin to break down.

At the end of anaphase, each opposite side contains a complete cluster of chromosomes.

Telophase
Each side of the cell now has a complete set of chromosomes. A nuclear envelope forms around each new set of chromosomes. The chromosomes uncoil so that proteins can be built. The spindle fibers disappear.

Cytokinesis (Cell Division, 2 daughter cells)
The cytoplasm is pinched in half, forming two new cells. These two cells are refered to as the daughter cells. Each new cell contains identical DNA with its own nucleus. After growth and replication, the cells repeat process 2-6 and divide again.

In summary, mitosis occurs in a 3-step fashion:
1. Replication of the genetic material in the parent cell.
2. Seperation of the replicated DNA and chromosomes.
3. Formation of two daughter cells.

CELL DIVISION: TERMS

To better understand cell division, you should familiarize yourself with the terms below (listed in alphabetical order).

Cell - Smallest unit that can carry out all the activities necessary for life; from Latin cella, meaning "small room"

Chromosome - Compact structure of tightly coiled DNA that forms prior to mitosis; from the Greek chrōma, meaning "color"

Chromatid - A threadlike complex of DNA and proteins in the nucleus of a nondividing cell; chromatin, plural form

Cytoplasm - Material inside the cell membrane containing the necessary components for cell life, mostly fluid; from the Greek plassein, meaning "to form"

DNA - (DeoxyriboNucleic Acid) An acid found inside the cell nucleus that carries the genetic information in the cell and is capable of self-replication. Consists of two long chains of proteins that determines individual hereditary characteristics.

Mitosis - Nucleur division; involves copying and separating chromosomes into two new nuclei; from the Greek mitos, meaning "thread"

Nuclear membrane - The double-layered material enclosing the nucleus of a cell, also called nuclear envelope.

Nuclei - A membrane-bound organelle that directs cell activities and stores DNA; from the Latin nucleus, meaning "nut or kernel"; nucleus, plural form

Spindle fibers - A cluster of microtubules that direct the movement of the chromosomes for proper cell division.

CELL DIVISION: REVIEW

Take the cell division quiz to see how much you've learned. After you answer a question, you may click [see answer] to see the correct answer immediately; or you may choose to compare all answers after you have completed the test.

1) What are the steps of mitosis from beginning to end?

2. During metaphase, where do the chromosomes line up in the cell?

3. During DNA replication, what is true about the DNA that is copied?

4. Which phase do spindle fibers first appear in?

5. During which phase is the cytoplasm of the cell pinched in half to form two new cells?

CELL DIVISION: ANSWERS

Compare your answers from the Review with the correct answers. If you got any answers incorrect, you may read about the Process again.

1) What are the steps of mitosis from beginning to end?

2. During metaphase, where do the chromosomes line up in the cell?

3. During DNA replication, what is true about the DNA that is copied?

4. Which phase do spindle fibers first appear in?

5. During which phase is the cytoplasm of the cell pinched in half to form two new cells?

CELL DIVISION: OTHER

E-mail addresses are provided for any further questions you may have. Additional links to cell division information are also provided if you wish to learn more.

CONTACT
E-mail Paulette Pham any questions/comments regarding the site, cell division, mitosis images, etc.
E-mail Kim Pham for technical difficulties, troubles viewing the site, or any other problems.

ADDITIONAL INFORMATION
Holt Biology: Visualizing Life An online text book with extended information about cell division and an in-depth look of biology.
Biology Project: Cell Cycle & Mitosis A tutorial about cell division and mitosis. Includes DNA basics, a brief overview of the cell cycle and mitosis, and a self test.
Microscopy: Interactive Java Tutorial Learn the steps in mitosis with an interactive Java tutorial. Includes photographs and details.

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Site created 02/29/04

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