1. 3.1 Discovering Cells 7.1 All living organisms are composed of cells, from just one to many trillions, whose details usually are visible only through a microscope

2. An Overview of Cells Key concept: Cells are the basic units of structure and function in living things. Examples of function: obtaining oxygen, getting rid of waste, obtaining food, growing, and more… Cells function similarly in all organisms, they carry out the basic processes of life similarly Cells are so small they are measured in micrometers One square centimeter of Skin is more than 100,000 cells Cells are visible only through microscope

3. First Observations of Cells 1590ish invention of the microscope Key concept: The invention of the microscope made it possible for people to discover and learn about cells. Robert Hooke one of first people to observe cells built his own microscope- one of the best of his time observed cork which looked like small rectangular rooms they called cells

4. First Observations of Cells Anton van Leeuwenhook Dutch businessman Built simple microscopes in his spare time Looked at drops of lake water, scrapings from teeth and gums, water from rain gutters Animalcules- means “little animals,” small organisms that moved that he found in things like lake water

5. Development of the Cell Theory Schleiden- all plants are made of cells Schwann- all animals are made of cells Virchow- new cells are formed only from cells that already exist Until these men’s time people believed that cells can come from non-living matter

6. Cell Theory An explanation of the relationship between cells and living things i.All living things are made of cells. ii. Cells are the basic units of structure and function iii. All cells are produced from other cells

7. Unicellular and Multicellular Unicellular- single celled Multicellular- many cells Key concept: “In multicellular organisms, cells are often organized into tissues, organs, and organ systems. Tissue- a group of singular cells that work together Organs- is made up of different kinds of tissue Organ system- a group of organs wanted to what those