¨       Scientists use a variety of equipment and technology to conduct scientific experiments.

For example:

v      Computers

v      Electronic balances

v      Microscopes

v      Telescopes

A Common Measurement System

¨       Most scientists use the metric system when collecting data and performing experiments.

¨       The metric system is a decimal system of measurement whose units are based on multiples of 10.

¨       A revised version of the original metric system is called the International System of Units or SI.

Analyzing Biological Data

¨       Scientists record collected data in a table and then make a graph.

¨       A scientist can easily detect a pattern of change with data presented this way.

¨       With such large amounts of data, scientists use computers to help analyze it.

Ex) structure of molecules

¨       Computers also help gather data from satellites to make predictions about complex phenomena.

Ex) global climate changes

Microscopes

¨       A microscope is a device that magnifes images that are too small to see with an unaided eye.

¨       Light microscopes produce magnified images by focusing visible light rays.

¨       Electron microscopes produce magnified images by focusing beams of electrons.

Light Microscopes

¨       Light microscopes can produce clear images of objects at a magnification of about 1000 times.

¨       A compound light microscope allows light to pass through the specimen and use two lenses to form an image.

¨       Characteristics of a compound light microscope:

v      Used to observe dead organisms and their parts

v      Used to observe tiny organisms and cells while they are still alive

v      Chemical stains or dyes are used to show specific structures

v      Fluorescent dyes and a video camera can be used to produce moving 3D images such as cell movement

Electron Microscopes

¨       An electron microscope uses a beam of electrons to produce images almost 1000 times more detailed than light microscopes.

¨       Two main types of electron microscopes:

v      A transmission electron microscope (TEM) shines a beam of electrons through a thin specimen.

Ø       Reveal detail inside the cell

v      A scanning electron microscope (SEM) scans a narrow beam of electrons back and forth across the surface of a specimen.

Ø       Produce realistic 3D images on the surfaces of objects.

¨       Both require a vacuum to operate so samples must be preserved and dehydrated before they are placed inside the microscope.

¨       Living cells cannot be observed with an electron microscope.

Laboratory Techniques

Cell Cultures

¨       A cell culture is a group of cells grown in a nutrient solution from a single original cell.

¨       Cell cultures can be used to:

Ø       Test cell responses under controlled conditions

Ø       Study interactions between cells

Ø       Select specific cells for further studies

Cell Fractionation

¨       A technique that separates the cell into different parts is called cell fractionation.

¨       This process involves:

Ø       A special blender breaks cells into pieces.

Ø       Broken cell bits are added to a liquid and placed in a tube.

Ø       The tube is inserted in a centrifuge and spun 20,000 times per minute to separate the cell parts.

Ø       The densest parts settle to the bottom and least dense parts rise to the top.

¨       A biologist can then remove a specific part of a cell to be studied by selecting the appropriate layer.

Working Safely in Biology

¨       Before starting any activity, read all the steps and make sure you understand the entire procedure including any safety precautions.

¨       Always follow your teacher’s instructions.

¨       Ask for an explanation when you are in doubt about any part of an activity.

¨       Wash your hands thoroughly after every scientific activity!