# For Teachers

## Objectives

To set up a lesson plan, have the students learn the vocabulary terms since these terms will appear in the text and animations as you go through the module. Then have then do the pre-test. You may want to review cell structure with your own text and diagrams since the first part, Basic Cell Parts Involved In Mitosis, deals only with these parts. You may want to quiz the students on the parts mentioned as knowledge of these parts is essential to understanding the process of cell division.

The next section, Why Must A Cell Divide?, is a demonstration of the surface to volume ratio concept to show that the cell membrane cannot continue to diffuse in and transport in the food and oxygen that the cytoplasm needs if growth continues beyond a certain point. The student is directed to solve the mathematical problems of determining surface area and volume of cubes, and the ratios between the two. The purpose is to show that a cell has two choices, either divide or die. It may be helpful to review the mathematics involved before viewing this portion.

The section, What Does Mitosis Do?, deals with the functions of mitosis, growth and repair. The animations clearly show growth from infancy to adulthood and repair in the healing of a broken bone. After viewing the pictures, the student should be able to answer that particular question about the functions of mitosis.

The last section, Built-In Controls In Mitosis, shows one of the controls, contact inhibition, where cells placed in a petri dish will continue to divide until the bottom of the dish is filled and the cells are all in contact with one another. Then division stops. There are also “go, no-go” switches at certain points in the cell cycle and in mitosis itself. Further, cells have growth factors, proteins that promote cell division. Strands of DNA called genes direct the assembly of amino acids into proteins. If mutations occur in the DNA, then genes are altered resulting in a change in the function of one or more of the several proteins that normally control growth. Abnormal division, i.e., cancer will result. Abnormal cell division in cancer is also presented in animation.

## Vocabulary List

 Centrioles Chromatin Chromosomes DNA Mitosis Nucleus Nucleolus Organelles Diploid Haploid Receptors Ribosomes Cytoplasm Contact inhibition Spindle fibers

## Pre and Post-Exercise Questions

1. What are different methods of cell reproduction?
2. What is in the nucleus?
3. Describe the structure of a chromosome.
4. What is the function of the nucleus?
5. Why must a cell divide? Why can’t it just keep on growing?
6. What are the two functions of mitosis?
7. Is mitosis going on in your body right now?

1.
1. Fission – binary – cell divides into two equal halves (bacteria)
2. Budding – outgrowths from the outer surface of an organism
3. Asexual – mitosis – produces tow cells that are exact copies of the original
4. Sexual – meiosis - produces the sex cells and each cell has half the number of
2. The chromosomes.
3. Chromosomes are made of one long strand of DNA that is wound around bits of protein and all coiled up.
4. What is the function of the nucleus?
1. It plays a central role in cell reproduction, mitosis and meiosis.
2. The DNA of the chromosomes carries hereditary information that is passed on intact to new cells.
3. The DNA carries information for putting together proteins by ribosomes in the cytoplasm of the cell. Proteins are used for structure of cells and tissues, and most enzymes are proteins. Enzymes are involved in all of the cell’s chemical reactions.
5. As a cell gets larger, the ability of the outside, the cell membrane, cannot supply the inside, the cytoplasm and all of its organelles, with all that it needs. This is demonstrated by the surface to volume ratio of cells as they grow
6. Growth and repair.
7. Yes, in many parts of your body. Cells of your skin, digestive tract, tongue, and of course, if you have a cut or broken bone at the moment.