Cell Theory & Eukaryotic Structures Cellular timeline – 1665… Robert Hooke views cork under a microscope and describes tiny chambers he calls cells – 1674… Anton van Leeuwehoek observes single celled organisms in pond water using a microscope – 1838… Matthias Schleiden states that all plants are made of cells – 1839… Theodor Schwann states that all animals are made of cells – 1855… Rudolph Virchow… establishes the cell theory Cell theory – All living things are made of cells – Cells are the basic unit of life – New cells come from existing cells

Exploring the Cell Study called cytology – Light microscopy - a device using light and mirrors to magnify an object. Its resolution (measure of clarity) is limited to 0.2 mm. good for seeing the gross structure of most cells and bacteria most appropriate for viewing live specimens – Electron Microscopy - a device that concentrates a beam of electrons onto a plated surface. Its resolution is to around 2nm. (good for seeing organelles and some macromolecules) (SEM) scanning electron microscope - good for detailed investigation of surface structure (TEM) transmission electron microscope - good for seeing internal structures of cells – Cell fractionation uses a centrifuge to separate the parts of the cell by mass

Prokaryote vs Eukaryote Prokaryotes - no true nucleus – DNA is not separated from the rest of the cell (no nuclear membrane) but is concentrated in a nucleoid region Eukaryote - true nucleus – DNA is located in a membrane bound compartment called the nucleus The nucleus houses the genetic information of the cells. It is responsible for directing protein synthesis which effects every function of the cell. – area between the nucleus and the plasma membrane is called the cytoplasm contains the membrane bound organelles

Prokaryote vs Eukaryote Common features – plasma membrane - all cells are bound by a plasma membrane functions as a selective barrier - hydrophobic interior with hydrophilic exterior which is embedded with channel proteins used to transport materials. has a very large surface to volume ration in order to efficiently transfer gases, nutrients, & waste in and out of the cell

Prokaryote vs Eukaryote Prokaryote (Bacteria) – The cell performs everything required for survival Growth Reproduction Response to environment Movement Eukaryote (Protists, Fungi, Plants, Animals) – Larger and more complex than prakaryotes – Single celled (protists) or multicelled Cells may highly specialized to carry out specific functions