Methods of studying the cell
A light microscope consists of a system of objective and eyepiece lenses; the total magnification equals the product of the objective and eyepiece magnifications and usually reaches up to 2000 times. What matters is not magnification but resolving power, the ability to show two close points separately; the wavelength of light sets this limit. In an electron microscope the image is formed not by light but by a beam of electrons and is magnified hundreds of thousands of times; with it ribosomes, the endoplasmic reticulum and microtubules were discovered, and modern methods even give three-dimensional images of molecules. In the cytochemical method special dyes show where and how much of proteins, nucleic acids, fats and carbohydrates are in the cell. In centrifugation tissue is ground up and spun, and the nucleus, mitochondria and ribosomes separate by weight so that their properties can be studied. Today fluorescence microscopy and growing cells in artificial media are also widely used.
“Choose the method”. Match each question on the cards to a method: a) separating mitochondria from the nucleus, b) seeing where DNA is located in the cell, c) seeing the shape of a ribosome, d) watching a living amoeba.