Tools used in Biological Research

Microscopes Any tool used to magnify the image of an object.

Light Microscope - any device that uses light to produce an enlarge image of an object Magnification - to make an object look bigger. It is the ratio of image size to object size and is represented by the letter X Ex: 40 X = The image is 40 times bigger than life Resolution – How clearly you can see the object or the ability to see the fine detail of the object being viewed.

Simple Microscope - Has only one lens and only magnifies a little Ex : 5X and 10X

Compound Microscope - Uses a series of lenses to produce higher magnification and higher resolution. These can magnify up to 2000X Composed of Three Main Parts – 1. Optical System – All the lenses in the microscope 2. Mechanical System - All the hardware that the microscope is made of 3. Light System - Produces the light so you can see the object

Things look upside-down and backwards under a microscope due to the lenses.

Compound Light Microscope

Mechanical Light Brightness Control Ocular Tube / Ocular lens

NOTE: You should always start focusing a microscope using low power then switch to medium power, refocus and then to high power last. Three reasons to start focusing a microscope under low power: 1. Large Field Of View (FOV) – You can see more of the object using low power. 2. Larger Depth Of Field (DOF) – More of the object is in focus using low power. 3. Greater Brightness of Field – The object look brighter using low power.

1. Easier to find things when using LOW POWER

High Power Medium Power Low power Depth of Field 2. Easier to focus under LOW POWER due to a large Depth of Field

Magnification : The ability of a microscope to make things look bigger. 10X means the object looks 10 times bigger than it really is. The Total magnification of the microscope is calculated by multiplying the magnification of the eye piece time the magnification of the objective lens you are using. Eye piece X Objective = Total Magnification 10 x X 40 x = 400 x (Looks bigger then life)

Important Note: As you increase your magnification you see less of the object. Ex: If your FOV is 4 mm under 100 X Then your FOV is 1 mm under 400 X Inc. Magnification by 4 times : 100 X -> 400 X Dec. your FOV by 4 times : 4mm -> 1mm So you see less under high power but it looks bigger.

The most important term in microscope work is : Resolution - It is the ability to see fine detail when using a microscope or how shape the object looks. This is what you really pay for when you buy a microscope Expensive Microscopes have good resolution (Can cost up to $250,000.00) Cheap microscopes have poor resolution (Can cost as little as $50.00)

Stereomicroscope or Dissection Microscope For looking at the surface of an object

Phase Contrast Microscope Similar to a light microscope but uses polarized light to give good contrast, can view living specimens. These are more expensive and harder to use than a basic light microscope

Light MicroscopePhase Contrast

Electron Microscope Two Types: Transmission - Looks at inside Scanning – Looks at the outside Gives High Magnification and Excellent Resolution Very Expensive and very hard to use.

TEM Transmission Electron Microscope

SEM Scanning Electron Microscope

Leaf

Mouth of Dust Mite

Scanning - Tunneling Microscope Can look at atoms

Silicon atoms

Atomic Cartoon

Chromatography The process of separating chemicals based on their physical size or chemical properties by using special filter paper.

Small molecules Big Molecules

A few drops of black ink at the bottom produced these bands of color showing what colors make up the ink

Centrifuge Used to spin a solution to separate the particles based on their density. Heavy to the bottom, light on top

Electrophoresis A process that is used to separate pieces of DNA by placing the DNA in a special gel and adding electricity. Used a lot in police work to solve crimes

The 1978 Nobel Prize in Medicine was awarded to Daniel Nathans, Werner Arber and Hamilton Smith for the discovery of restriction endonucleases (enzymes), leading to the development of recombinant DNA technology. The first practical use of their work was the manipulation of E. coli bacteria to produce human insulin for diabetics Restriction Enzymes

First the strand of DNA is cut into pieces by special chemicals called Restriction Enzymes

Crime Scene The gel on the left shows comparisons of DNA fingerprints from a bloodstain discovered at a crime scene and from blood samples of seven suspects. Which suspect matches the DNA at the crime scene? Why?

Tissue Cultures Growing tissue outside the body Skin is grown outside the body to help burn victims One day many organs may be grown for transplant

Used in Cancer Research

Growing skin for a skin graft

Microdissection Using very small tools to dissect objects as small as individual cells This technique is used when cloning cells or in-vitro fertilization sometimes called “test tube babies”.

This scientist can remove a nucleus from a single cell with this equipment.

da Vinci Robotic Surgery

da Vinci Video

Diagnostic Tools Used in medicine and research to help investigate problems.

Magnetic Resonance Imaging

Positron Emission Tomography PET Shows brain activity

Pill Size Camera use to take pictures inside the intestines

Short TED Talks on Scientific Investigation Simple ideas that lead to scientific discovery Wacky History of Scientific Discovery