Microscopes and Other Tools

DISSECTING MICROSCOPE

• Allows you to see the surface of the specimen

• Light reflects off the surface of specimen

• Organisms can be alive

• Image is in color

• Seen in 3-D

• Not for viewing cells

COMPOUND MICROSCOPE

• Used to view cells• Magnification up to 1500 X (Most up to 400X)• Image appears upside down and backwards• We can look at living cells and small organisms• Specimen must be cut very thin because light must shine

through

SCANNING ELECTRON MICROSCOPE

• Allows you to see surface of specimen• Specimen is covered in a thin layer of gold which

allows electrons to “bounce off”• Viewed in a vacuum (all air is removed)• Specimen is NOT alive• Seen in black and white

and in 3D

PHASE CONTRAST MICROSCOPE

• Widely used for examining such specimens as biological tissues.

• Enhances contrasts of transparent and colorless objects • Able to show parts in a cell or bacteria, which would be

very difficult to see in an ordinary light microscope.• Important instrument in biological and medical research.• When dealing with transparent and colorless parts in a

cell, dyeing is an alternative but at the same time stops all processes in it.

• The phase contrast microscope has made it possible to study living cells, and cell division is an example of a process that has been examined in detail with it.

• The phase contrast microscope was awarded with the Nobel Prize in Physics, 1953.

CENTRIFUGE• Spins test tubes at a very high rotation

speed

• Separates out the parts of the liquid by density

• Ex. Separates blood into RBC, WBC, Plasma and Platelets

ULTRACENTRIFUGE

• Separates all of the organelles in a cell

GEL ELECTROPHORESIS

• Used to analyze DNA

• DNA is cut into pieces and “banding pattern” is seen– Pieces of DNA move through an “electric” field

SCIENTISTS

• Leewenhoek– First to look at cells in microscope

• Hooke– Named what he saw “cells”

• Schleiden– Looked at plant cells

• Schwann– Looked at animal cells

• Brown– Named the “nucleus”