Old dead guys to add to our Important People chart PersonOriginTime Frame Importance Robert HookeEnglish16651 st to identify/name cells Anton van Leeuwenhoek Dutch1674One of the 1 st to describe living cells Matthias Schleiden German1838Plants are made of cells Theodor Schwann German1839Animals are made of cells Rudolf Virchow German1855New cells come from old cells Robert Hooke Anton van Leeuwenhoek Matthias Schleiden Theodor Schwann Rudolf Virchow Cell theory: 1. All organisms are made of cells 3. Cells are the most basic unit of life 2. New cells are produced from other living cells Cells come in a variety of size, shapes, and functions all still have a membrane and DNA We can put cells into 2 categories: Eukaryotes and Prokaryotes Eukaryotes have a nucleus Prokaryotes DONT have a nucleus Wait. whats a nucleus? Nucleus = where the DNA is located and acts as the brain of the cell The cell membrane is made of 2 layers (lipid bilayer) made of phosolipids these help make the membrane strong & flexible The cell membrane is selectively permeable it only lets certain things cross Can you think of other example of selectively permeable things? Some molecules require energy to cross; some dont Ex. Diffusion = movement from high concentration to low Passive transport DOESNT require energy particles want to reach equilibrium Osmosis = diffusion of water Water moves from high conc. to low This means water moves to where there are more particles (because there is less water there) IsotonicHypertonicHypotonic Types of solutions Above strength (more particles outside) Water moves out Cell shrinks Same strength Water movement is equal Cell stays the same Below strength (less particles outside) Water moves in Cell swells Facilitated diffusion = proteins help molecules diffuse Still passive (no energy used) Active transport REQUIRES energy moves from low conc. to high (opposite of passive) protein pumps help with this Ex. Endocytosis = taking material into the cell Ex. Exocytosis = releasing material out of the cell