Cell Theory and Cell Study The Cell Theory

Cell Theory and Cell Study

The Cell Theory • The cell is the basic unit of structure of all living things. • All living things are made up of cells. • The cell is the basic unit of function of all living things. • Cells come from pre-existing cells.

Exceptions to the Cell Theory • These are facts that can not be explained by the Cell Theory. • Viruses are not made up of cells, but they do contain genetic material. • The first cell could not have arisen from a previously existing cell, Scientists don’t know the origin of the first cell.

History of Cell Study • Scientists did not know much about cells until the discovery of the microscope. • Cells are so small they can not be seen w/o a microscope. • Anton van Leeuwenhoek- Dutch naturalist (1600’s). Developed the first microscope. • Robert Hooke- English (1665) was the first to develop a compound microscope. He came up with the term cell.

History cont…. . • Robert Brown- (1831) discovered the nucleus of the cell. • Matthias Schleiden- (German, around 1830’s) a Botanist, concluded that all plants were made up of cells. • Theodor Schwann- (German, worked during the same time as Schleiden), studied animal cells. Concluded that animals were made up of cells. • Rudolf Virchow- (1858) concluded that all new cells must come from previously existing cells.

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Tools and Techniques

The Compound Microscope • Microscopes are used to study materials that can’t be seen with the naked eye. • Microscopes use two lenses (compound microscope) to increase the size of a specimen. • A specimen must be thin enough for light to pass through it. • The total magnification of an object is found by multiplying the magnification of the objective x the magnification of the eyepiece.

The Dissecting Microscope • Allows the study of large specimens. • It has two eyepieces and two objectives. • It has low power magnification and 3 D quality. • It is also called a Stereo-microscope.

The Electron Microscope • Can magnify up to 100, 000 x. • Cannot use live specimens. • Use a narrow beam of electrons instead of light. • Magnets are used to focus the electron beam.

Magnification • Compound microscopes- each lens enlarges the image. • Total magnification is determined by multiplying the power of the eyepiece lens x the power of the objective lens. • Total magnification refers to the total amount the image is enlarged. • The unit of length used to measure specimens is the micrometer (u).

Staining Techniques • Many parts of the cell are colorless and hard to see. • Staining techniques “color” certain cell parts so they can be more easily studied. • The most commonly used stains are Methylene Blue, and Iodine (Lugol’s Solution).

The Centrifuge • Instrument used to separate cell parts. • Separate parts according to density. • Material is spun around in a test tube at very high speeds. • Heaviest material is at the bottom, lightest is at the top.