Week 10 - Cells

1 Plant and Animal Cells

Lesson 5

Science in Action 8
Pages 103-108, 111-114

ScienceFocus 8
Pages 115, 121-127

Lesson 5: Plant and Animal Cells

Background Information
Figure 1. Illustration of the major regions of a living cell.

When Robert Hooke observed cork in 1665, he was looking at dead cells. All he could see was the cell wall of a plant cell. Living cells are dynamic and have several things in common.

All cells have a cell membrane . This is the outer boundary of the cell and controls what enters and leaves the cell.

All cells have a gel-like cytoplasm . The cytoplasm contains the chemicals and water that the cell needs to survive. It also contains the tiny structures that carry out the life process for the cell.

All cells, with the possible exception of red blood cells in humans, contain hereditary material. The hereditary material determines the structure and the function of the cell and is found in the nucleus of plant and animal cells. The Cell Factory

Each cell in your body has a specific job to do. The activities in your cells might be compared to a factory that operates around the clock making dozens of different products.

The factory has a definite structure. A cell is similar. It functions inside a structure called the cell membrane.

Products enter and leave the factory through doors. Similarly, substances move into a cell and products and wastes move out.
Machinery inside the factory make products and generate wastes that must be removed. The cell contains tiny structures that make products and generate wastes that must be removed.
The factory is controlled from a central office. The nucleus of a cell is described as the control center of the cell.

Animal Cells

Figure 2 represents the main parts of an animal cell.
  • Animal cells are surrounded by a cell membrane. You will learn more about the cell membrane in another lesson.
  • Most animal cells contain a nucleus. The nucleus is the largest structure in the cytoplasm. The nucleus directs all the activities of the cell. Chromosomes are found inside the nucleus. The chromosomes contain the hereditary material.
  • The cytoplasm of an animal cell contains structures called organelles. The nucleus, for example, is an organelle. Each organelle has a specific job or jobs. Some organelles break down food molecules. Others transform the chemical energy in food into another form of chemical energy that the cell can use. Some organelles move wastes to be expelled from the cell. The vacuoles are storage organelles in cells. They may store water, waste products, foods, and other cellular materials.

Plant Cells
Figure 3 represents the parts of a plant cell.

A plant cell has many of the same parts as an animal cell. There are two main differences between plant and animal cells.
  • Plant cells have a cell wall. The cell wall is a rigid structure that supports and protects the plant cell. It is composed of fibres made of cellulose. You are familiar with these fibres if you ever got the stringy stuff in celery stuck between your teeth.
  • Plants cells have the ability to manufacture their own food through the process of photosynthesis. Photosynthesis occurs in chloroplasts. Chloroplasts are organelles that contain the pigment chlorophyll. Chlorophyll is the pigment that traps and transforms light energy into chemical energy and stored in sugar molecules.

Exercise 2.1: Cells Alive
Experiment Time - Cells

Locate the web site named An Introduction to Microscopy. 
Select two organisms from the jar and read about more about them in the virtual field guide. 

Check Your Understanding
Do the Check and Reflect questions found on page 109.
Make sure you read all the information given and then compare the differences between animal and plant cells. 

Go to the Cells Alive web site http://www.cellsalive.com/cells/3dcell.htm ) and locate the model of the animal and plant cells. First click on the picture of the cell then click on the following structures-cell membrane, nucleus, vacuole, cytoplasm (cytosol), cell wall, and chloroplast

Use the information on this web site to complete the Animal and Plant Cell columns of your Cell Structure Chart. 

1. Answer the questions as stated here for both animal and plant cells: a) State whether the structures appear in animal, plant or both cells, then 
b) describe the structures as listed in the chart below.
Cell Structure
cell membrane
cytoplasm (cytosol)
cell wall
2. Answer the question as stated!
3. Answer the question as stated!
Do the Check and Reflect questions found on page 114.

1. Answer the three questions as stated.
2. Answer the question as stated!
3. Answer the question as stated!
4. Answer the question as stated!
5. Answer the question as stated!
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