7-4 The Diversity of Cellular Life

1. 7-4 The Diversity of Cellular Life

2. The Diversity of Cellular Life • Life on Earth is very diverse, but all living things are composed of cells, use the same basic chemistry, follow the same genetic code, and even have the same kinds of organelles

3. Unicellular Organisms • A single-celled organism is also called a unicellular organism. Unicellular organisms do everything that you would expect a living thing to do. They grow, respond to the environment, transform energy and reproduce. • Unicellular organisms dominate life on earth

4. Multicellular Organisms • Organisms that are made up of many cells are called multicellular. All multicellular organisms depend on communication and cooperation among specialized cells. Cells throughout an organism can develop in different ways to perform different tasks. This process is called cell specialization.

5. Specialized Animal Cells • Animal cells are specialized in many ways: • Red blood cells are specialized to carry oxygen • Cells specialized to produce proteins, for example, are found in the pancreas • The human ability to move is a result of the specialized structures of muscle cells. These cells generate force by using a dramatically overdeveloped cytoskeleton

6. Specialized Animal Cells • Skeletal muscle cells are packed with fibers arranged in a tight, regular pattern. • These fibers are actin microfilaments and a cytoskeletal proetein called myosin • When they contract, muscle cells use chemical energy to pull these fibers past eachother, generating force

7. Specialized Plant Cells • A plant rapidly exchanges carbon dioxide, oxygen, water vapor, and other gases through tiny openings called stomata on the undersides of leaves. • Highly specialized cells, known as guard cells, regulate this exchange. Guard cells monitor the plants internal conditions, changing their shape according to those conditions.

8. Specialized Plant Cells

9. Levels of organization • The levels of organization in a multicellular organism are individual cells, tissues, organs, and organ systems

10. Levels of Organization

11. Levels of Organization

12. Tissues • A tissue is a group of similar cells that perform a particular function • Most animals have 4 main types of tissue: muscle, epithelial, nervous, and connective tissue.

14. organs • Many tasks in the body are too complicated to be carried out by just one type of tissue. In these cases, many groups of tissues work together as an organ

15. Organ system • A group of organs that work together to perform a specific function is called an organ system