Microscopy

MICROSCOPE 18th Century

A compound microscope used in 18th-century France A compound microscope used in 18th-century France. First developed in the late 16th century, compound microscopes use two or more sets of lenses to achieve high magnification.

TYPES OF MICROSCOPE

I. OPTICAL MICROSCOPES

Hooke’s Microscope

English scientist Robert Hooke built this microscope in the 17th century and used it to conduct pioneering research. He discovered the cell structure of plants by observing a thin slice of cork under his microscope.

Important Tools in Biology Microscopes – is an instrument that uses lenses to produce an enlarged and focused image of a specimen. Two properties: 1. Magnification – is the ratio between the image size and the object size. 2. Resolution (Resolving power) – refers to the smallest degree of separation at which two objects are viewed as distinct from one another, rather than as a blurry, single image.

Micron (µ)- unit of measurement used in microscope study. Conversion of Units: 1µ = 0.000001m 1µ = 0.001mm Examples: Range of Bacteria = 0.5 to 2µ Range of some nerve cells = 1000µ

Types of Microscopes 1. Compound Light Microscope – focuses and bends visible light through a specimen to produce a magnified image. *Magnification = up to 1500x *Resolution = 0.1 to 0.2µ

TM =OLM x OL Computation for the size of specimen Where: TM = Total Magnification OLM = Objective Lens Magnification OL = Ocular Lens

Types of Microscopes 2. Stereomicroscope (Dissecting Microscope) – consists of two eyepieces and two objective lenses. - used for dissecting small specimens. Magnification = ranging from 4x to 50x

Resolution power = about 1,000 times Types of Microscopes 3. Electron Microscope – uses a beam of electrons instead of light to create image. - the beam of electrons is focused using magnetic lenses. Resolution power = about 1,000 times

Types of Electron Microscopes Transmission Electron Microscope (TEM) – uses a magnetic field beam to focus a beam of electrons through a thin section of the specimen. Magnification = about 100,000 times

Types of Electron Microscopes b. Scanning Electron Microscope (SEM) – gives a surface view of a three-dimensional specimen by bouncing electrons off its surface. Magnification = about 10,000 times

Types of Electron Microscopes c. Scanning Tunneling Microscope (STM) – allows viewing of atoms on the surface of a solid. Magnification = over 1 million times

OTHER SCIENTIFIC TOOLS Ultracentrifuge – a machine used to separate suspended particles in a mixture.

OTHER SCIENTIFIC TOOLS 2. Chromatography – used in separating substances in a mixture. Types: Paper Chromatography Column Chromatography

OTHER SCIENTIFIC TOOLS 3. Electrophoresis – used to separate substances in a mixture according to how fast they move when subjected to an electric current. - commonly used to purify proteins based on their sizes and shapes.

OTHER SCIENTIFIC TOOLS 4. X-ray Diffraction – useful for analysis of protein crystals using X-rays of a single wavelength.

OTHER SCIENTIFIC TOOLS 5. Spectrophotometer – used to determine the amount of proteins or nucleic acid present in a solution. - measures the amount of light absorbed by the solution at specific wavelength.

OTHER SCIENTIFIC TOOLS 6. Computer – useful in storing vast amounts of information. - also used to organize data, make long and complex calculations and make graphs to summarize results.