Biology cells History of cell theory Before microscopes

Biology : cells

History of cell theory ► Before microscopes people believe that illnesses were caused by the supernatural. ► They had no idea bacterial and viral organisms existed. ► Microscopes allowed scientists to view and study cells – the basic units of living organisms.

Cell theory: ► Robert Hooke – scientist used compound light microscope to study cells of oak and cork. ► Hook observed geometric shapes – called cells. Published drawings and descriptions. ► Another scientists : Matthias Schleiden observed cells, as well as Theodore Schwann.

Cell theory ► 1. all organisms are composed of one or more cells. ► 2. the cell is the basic unit of organization of organisms. ► 3. All cells come from preexisting cells.

Types of Microscope ► Development of light microscopes : § Microscope van Leeuwenhoek – simple light microscope. One lens. Natural light. § Compound light microscope – series of lenses to magnify objects in steps. § Electron microscope – 1950’s – uses beam of electrons to magnify structures up to 500, 000 times!!

Two basic cell types ► Prokaryotes – do not have membrane bound organelles. Unicellular organisms such as bacteria. ► Eukaryotic – contain membrane bound organelles. Each organelle has a specific function for cell survival.

Scientific Diagram ► Draw and label on the given paper, a eukaryotic cell, and a prokaryotic cell. ► Label structures. ► Attach ► P. 180 to notebook. Color, and label.

1 pg essay writing each! ► Prokaryotic/eukaryotic p. 180 1 page essay question : Look at the eukaryotic and prokaryotic cells. § § How are they similar? How are they different? ► Animal and plant cell p. 192 ½ page essay question: Look at the diagrams of the plant and animal cells. § How are they similar? § How are the different?