CELLULAR HISTORY

Knowledge of cells originated from English scientist Robert Hooke in 1665 →Studied thin sections of cork and saw boxlike cavities he called “cells” Robert Hooke A. Cellular Scientists

Dutch scientist Antony van Leeuwenhoek examined pond water in 1676 →observed “animalcules” or tiny animals o Were single-celled amoeba, paramecium, and other water-borne pathogens Anton van Leeuwenhoek Water flea daphnia found in pond water

Matthias Schleiden in 1838 studied plants →cells make up every part of plant – stems, roots, leaves, flowers Matthias Schleiden

Theodor Schwann in 1839 viewed cartilage tissue cells →animals are also made out of cells o Published theory that cells are basic unit of life Theodor Schwann

Rudolf Virchow used work of Schwann and Schleiden to advance cell theory in 1858 Virchow

→Cell theory o All living things are made of one or more cells o Cells are basic units of structure and function in organisms o All cells arise from pre-existing cells Apple cells

living organisms may consist of one cell (bacteria) or many cells (plants and animals) that act as a unit or in coordination with each other Staphylococcus aureus Elodea plant

B. MICROSCOPE STRUCTURE Microscope: instrument used to magnify very small objects

Microscope PartsFunction ArmConnects to base and supports microscope head, also used to carry the microscope. BaseBottom of microscope, supports it and houses light source Body tubeHolds eyepiece in place above objective lens Course adjustmentFocuses microscope by moving stage up and down in large increments DiaphragmControls amount of light reaching specimen, located above light source and below stage Fine adjustmentSharpens focus of microscope by moving stage up and down in slight increments Light sourceLow voltage, halogen bulb for microscope, typically located in base

Microscope PartsFunction ObjectivesPrimary optical lenses on a microscope that magnify image  Scanning 4X – used to locate specimen  Low power 10X – used to locate specific area on specimen  High power 40X – used to magnify specific area on specimen Ocular lens (eyepiece) 10X Lens at top of microscope that eye looks through Revolving nosepieceHouses objectives mounted on a rotating turret so different objectives can be conveniently selected StageWhere specimen to be viewed is placed Stage clipsHolds the slide in place

AccessoriesFunction Cover slipSquare piece of glass or plastic to hold specimen on slide ForcepsType of tweezers used to grasp specimen SlidePiece of rectangular glass on which specimen is placed; held by stage clips Wet mountSetting specimen on slide, covering with a drop of water to stabilize specimen

QUIZ – can you name all the parts?

C. MAGNIFICATION Magnification of objective is not total magnification – must consider power of ocular lens, too –M–Multiply ocular lens by objective lens for correct magnification Ex: ocular lens has magnification of 4X. If objective lens is 40X, what is total magnification? –4–4 x 40 = 160X Ex: ocular lens has magnification of 10X. If objective lens is 100X, what is total magnification? –1–10 x 100 = 1,000X