Sections 4.1, 4.2 CELLS AND MICROSCOPES

 Microscopes allow us to identify organisms that cause food to spoil and cause disease.  1665 Robert Hooke- used simple microscope to look at cork. Saw little “rooms” which he called cells. MICROSCOPES

 1700s- Anton von Leewenhoek used a microscope to look at pond water and observe algae and other protozoans MICROSCOPES

 Work with microscopes led to the development of cell theory  1) all living things are made of at least one cell  2) cells are the basic unit of structure and function in living things  3) cells come from pre-existing cells  Cells may be prokaryotic (no nucleus or organelles) or eukaryotic ( have a nucleus and organelles) CELL THEORY

 Compound light – uses a slide, specimen must be thin and transparent, specimen may be alive  Cannot magnify more that 1000 times TYPES OF MICROSCOPES

 Much greater magnification and resolution  Up to 100, 000 times  Specimen must be dead and prepared specially  TWO TYPES  Scanning electron microscope – SEM – surface details  Transmission electron microscope- TEM – internal cells structures ELECTRON MICROSCOPES

SE MICROGRAPHS

TE MICROGRAPHS

 Use a circle as field of view  Give the diagram a title  Use color when appropriate  Use pencil  Label each structure, use straight lines  Identify the magnification  Total magnification = eyepiece x objective HOW TO MAKE GOOD DRAWINGS

 Eyepiece = 10 x  Low power objective = 4x  Medium power objective = 10x  High power objective = 40 x  Magnification numbers are printed on objectives. CALCULATING MAGNIFICATION