1. Tissues: Beyond Cells

2. All cells come from previously existing cells. One fertilized egg (zygote) undergoes mitosis many, many times to produce a baby. An adult human contains 75 – 100 trillion cells. 300 different types of cells in the body. Mitosis

3. How does one fertilized egg develop into all of the different types of cells found in a human? fat cells bone cells skin cells muscle cells

4. Answer: Cell Specialization Specialized cells have physical and chemical differences that allow them to perform different functions Red blood cells carry oxygen in the blood Nerve cells transmit electrical impulses Plant leaf cells perform photosynthesis

5. Genes How did one cell give rise to so many different types of cells in one organism? Genes (base pair sequences) turn on and off to control the characteristics and functions of a cell. Many factors influence what genes are turned on and off, including the environment and neighbouring cells.

6. Stem Cells Stem cells are undifferentiated cells that can divide to form specialized cells.

7. Levels of Organization Cells in organisms are organized into tissues. Tissues are collections of similar cells that perform a particular function. Tissues are organized into organs. Organs are organized into organ systems.

8. More than one kind of cell or tissue are found in any organ.

9. Different cells, tissues, organs and organ systems are found in animals and plants.