Transcript File - Life Science

Seeing is Believing
A lesson about Microscopes
By Sarah O’Rourke, Fairfield Middle School &
M. Kathleen Stansbury, Tuckahoe Middle School
What in the world is that?
What in the world is
that???
What in the world is
that???
What in the world is
that???
What in the world is
that???
What in the world is
that???
What in the world is
that???
What in the world is
that???
What in the world is
that???
What in the world is
that???
See how many pictures
you can guess correctly on
your Tic-Tac-Toe!
Tools in Science
Microscope Invented
• Hans & Zacharias Janssen
o Invented the first simple microscope
o Later, he made the 1st compound microscope (2
lenses)
o Allowed people to see things never before seen!
Robert Hooke 1655
• Used microscope to look at oak cork
• He observed “tiny little boxes”
• Called structures “cells”
Review
• Who named cells because they looked like “tiny
boxes”?
a.
b.
c.
d.
Francesco Redi
Louis Pasteur
Robert Hooke
Albert Einstein
Anton Van Leeuwenhoek
1675
• Used a simple microscope (1 lens):
o Observed blood, rainwater, sperm etc.
• Called them “animalcules” because they looked
like little animals
Matthias Schleiden 1838
• German botanist
• Discovered that plants are also made of cells!
Theodor Schwann 1850
• German zoologist
• Viewed animal parts under microscope
• Discovered animals were made of cells
Rudolph Virchow 1858
• German Doctor
• Concluded that all living cells come only from other
living cells
Review
• Who was the first person to observe living cells? (He
called them animalcules)
a.
b.
c.
d.
Robert Hooke
Francesco Redi
Anton van Leeuwenhoek
Rudolph Virchow
Cool Jobs In Science
• Molecular Biology
Why is it Important?
• The microscope allowed scientist to observe things that could
not be seen with the naked eye
o Cells for example!
• Makes things appear larger than they really are!
Your Design Task
Problem
You are a field biologist. In
order to find the most
extraordinary specimens, you
need to go into extreme
environments. On your latest
adventure, you forgot your
field microscope. Create a
microscope that is portable
and can be used in these
environments.
Research/Background
Click picture…
Your Design Task
Materials:
• Building materials from recycle bin
o
o
•
•
•
•
cardboard tubes
plastic bottles
Card stock/ index cards
Construction paper
Magnifying lenses
Small flashlight such as a finger light
Tools
•
•
•
•
Markers
Scissors
Tape
Ruler
Your Design Task
Constraints/ Restrictions/ Rules:
• Must be in a team of 2
• You have 30 minutes to design/build
• Complete your design sketch before you get
materials
• Your microscope must fit in a shoe box and survive a
durability “Shake Test”
Goal
Design a portable and durable microscope
that magnifies a specimen.
How does it Work?
• Microscopes use glass lenses to bend light
• This makes things appear larger or smaller depending on the
shape of the lens
• Compound microscopes: have more than one lens!
o This means they can magnify things even more!
Parts of a Microscope
Function of Parts
• Body Tube: separates eyepiece from
objective lens
• Eyepiece: contains lens that magnifies
10X
• Nosepiece: holds objectives lenses
and allows rotation
Function of Parts
• Objective lens (High Power): Magnifies 40X
• Objective lens (Low Power): Magnifies 10X
• Coarse Adjustment Knob: moves body tube
to focus with low-power objective lens
• Fine Adjustment Knob: moves body tube to
focus with high-power objective lens
Function of Parts
• Arm: supports the body tube
• Base: supports the microscope
• Stage: supports the slide being used
• Stage clip: holds the slide in place
Function of Parts
• Diaphragm: controls the amount of light that
comes through the stage
• Mirror/Light Source: reflects light upward
through diaphragm
Comparing Powers of Magnification
We can see better details with higher the
powers of magnification, but we cannot see
as much of the image.
Which of these images
would be viewed at a
higher power of
magnification?
What’s my power?
To calculate the power of magnification, multiply the power of the
ocular lens by the power of the objective.
What are the powers of
magnification for each of
the objectives we have on
our microscopes?
Calculating Magnification
• To find the total magnification of a compound microscope
you must multiply the magnifying power of both lenses!
• Example: Ocular Lens (Eye Piece)= 10X magnification
Objective Lens = 50X magnification
Total magnification = 10 X 50 = 500X
Practice
• Ocular Lens is 10x & Objective lens is 7x Total
Magnification?
• 10 X 7 = 70x
• Ocular Lens is 4x & Objective lens is 10x Total
Magnification?
• 4 X 10 = 40x
Try out a real microscope!
Getting Into Focus
•
•
•
Focusing your microscope
Make sure the light switch is turned on.
Place a slide onto the stage & secure it using the stage clips
Turn the nose piece until the smallest objective lens clicks into place
Start by turning the coarse adjustment knob slowly until you begin to see the
squares of the fabric through the eye piece.
Do NOT touch this know again once it is in focus!
Next turn the fine adjustment knob slowly until the objects appear very clear.
Repeat these steps for the remaining two objective lenses (medium and high).
•
•
•
•
Cells under the Microscope
Label what you are observing
Calculate the total magnification by multiplying the eyepiece & the objective lens
Follow the directions above to get your specimen into focus
•
•
•
•
•
Microscopes Today
Electron Microscopes
• Today scientists can use electron microscopes to
look inside cells!
• These microscopes use electrons instead of light to
magnify object even more!
o Same particles that light up your television!
Scanning Electron
Microscope
Transmission Electron
Microscope
• The scanning electron
microscope (SEM) uses
a focused beam of
high-energy electrons
to generate images of
the surface of a solid
specimen.
• A technique where a
beam of electrons is
transmitted through an
ultra-thin specimen. An
image is formed from the
interaction of the
electrons transmitted
through the specimen.
the image is magnified
and focused onto an
imaging device or on
a layer of
photographic film.
Recent Discovery in
Microscopy
The foot is covered by tiny hairs that spilt
off into smaller and smaller hairs. Because
these hairs are so small , it creates a
molecular forces that allows the Gecko to
be able to stick to surfaces with out glue!