Investigation 7-1
Cell Structure and Function
Introduction
Although the cell is considered to be the building block of all organisms, cells differ enormously in shape, size (structure)
and capability (function). Prokaryotic (bacteria) cells are less complex, are usually found only in unicellular organisms
and have more limited capabilities than eukaryotic (animal and plant) cells. Multicellular organisms are made up of highly
integrated combinations of specialized eukaryotic cells, but some complex organisms consist of a single eukaryotic cell.
In this investigation, you will look at four different cell types from a frog and explain how the structure of each of the cell
types helps it to fulfill its function in the body.
1) Blood Cells – These cells carry oxygen throughout the entire body. They travel through the circulatory system, a
system of smooth tubes called veins, arteries, and capillaries. The capillaries are often so small that only one blood cell
can pass at a time.
2) Sperm Cells – Their function is to carry the DNA they contain to an egg cell. Only one sperm cell fertilizes an egg cell.
3) Skin Cells – The skin is made of multiple layers. The outermost layer (epidermis) provides protection. The dermis
(inner layer) provides structure and flexibility. It also contains important glands and nerves.
4) Epithelial Cells – These cells are the inner lining of many organs, such as the lungs, kidneys, and intestines. They
facilitate nutrient and gas exchange.
Procedure
1. Place one of the four cell type slides on the microscope stage and get it into focus on low power. Have your partner
look at the cells.
2. Switch to medium power, and refocus. Have your partner look at the cells.
3. Switch to high power, and refocus. Have your partner look at the cells.
4. Decide which magnification is best for drawing the cells.
5. Draw a few cells (in the case of the sperm, blood, or epithelium cells) or a section of cells (in the case of the skin crosssection). Make your drawing as detailed and accurate as time allows. Label all visible structures in the drawing according
to the directions below. Remember to title the drawing and list the magnification used.
Blood/Epithelium: Label the nucleus, cell membrane, and cytoplasm
Sperm: Label the head and flagella (whip like structure used for movement)
Skin: Label the epidermis and dermis
6. Allow everyone in your lab group to make their own drawings from the microscope (not by copying another
drawing).
7. Return the slide to the box and repeat steps 1-5 with the other three slides.
Analysis
Obtain a poster paper from the teacher, divide it into three sections and label with Blood, Sperm, and Skin. Working in
pairs, draw ONE of each type of cell in each section. Under the drawing, write a summary paragraph (4+ Sentences) to
explain what you have seen. Your summary should include a statement that describes the relationship between structure
and function in cells. You should then back up your statement with specific descriptions of each cell type that you have
looked at. For each cell type, describe the structure you observed; describe the function of those cells; then explain how
the structure relates to the function. You may label important parts of your drawing to help you description. When you are
finished, staple your individual microscope observation drawings to the back, write your names are on it, and turn it in.