Transcript Tools used in Biology PPT

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
/ Ocular lens
Ocular Tube
Mechanical
Light
Brightness Control
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
Depth of Field
High Power
Medium Power
Low power
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 Microscope
Phase 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
Restriction Enzymes
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
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