Plant and Animal Cells

Cells vary in size, shape, and function. After many hours of peering through microscopes, scientists have determined that there is no single common cell, but all plant and animal cells have certain features in common.

Examining Animal Cells The entire animal cell is surrounded by a cell membrane. Inside the cell membrane, generally near the center of the cell, is the nucleus. The nucleus is surrounded by a fluid called the cytoplasm.

The Cell Membrane The membrane is the outermost edge of the animal cell. Composed of protein and lipid (fat) molecules, the membrane connects the cell to the outside environment. The membrane holds the contents of the cell in place and regulates the movement of materials into and out of the cell.

The Cytoplasm The cytoplasm is the area of the cell in which the work is done. Nutrients are absorbed, transported, and processed within the cytoplasm As the cell processes nutrients, waste products build up.

The cytoplasm stores the waste until it can be disposed of. This process is known as exocytosis of waste.

Some animal cells have a flagellum (plural is flagella), a whiplike tail to help them move.

The Nucleus The nucleus is the control center of the cell. It stores the information that tells the cell what to do and when. This genetic information is organized into threadlike structures called chromosomes.

Each chromosome contains many different units. These units, called genes, determine the specific traits of an individual. Every cell in an organism contains the same genes. The nucleus is also involved in cell division.

Identify Plant Cell Structures Plant cells also have structures not found in animal cells.

The cell membrane of a plant cell is surrounded by a cell wall. Composed of cellulose, the cell wall protects and supports plant cells. Gases, water, and some minerals can pass through small openings in the cell wall.

Unlike animal cells, plant cells can make their own food. Specialized organelles, called plastids, are associated with the production and storage of food. (An organelle is any structure found in the cytoplasm that has a specific form and function.)

Plastids are chemical factories and storehouses for food and colour pigments. Chloroplasts are plastids that contain green pigment chlorophyll, which is used in photosynthesis.

Photosynthesis Photosynthesis is the process by which plants combine carbon dioxide with water to make sugar and release oxygen. A large part of the cytoplasm of a plant cell consists of a fluid- filled space.

Vacuole This space is called a vacuole. The vacuole is filled with water, sugar, minerals, and proteins. Animal cells may have vacuoles, but they are much smaller.

Did You Know? Cells vary greatly in size and shape. An ostrich egg is the largest single cell, at about 75mm in diameter. A human nerve cell can be as long as 1000mm, but the same cell is only 0.01mm in diameter

What are the function of the nucleus and the cytoplasm of the cell? Self Check What are the function of the nucleus and the cytoplasm of the cell? Where would you find the genetic information in a cell? List two ways in which plant cells differ from animal cells. a) What is the function of the chloroplasts? b) Why are chloroplasts not found in animal cells? 5. Predict what might happen to a cell if the cell membrane were replaced by a plastic coating that allows nothing to get through. Explain your prediction.