Transcript Sizes of Things - Lincoln-Sudbury Regional High School

Measurement &
Microscopes
Sizes of Things
Size relative
Prefix
Meaning
to a meter
Length
Kilo-
thousand
103
kilometer (km)
Centi-
hundredth 10-2
centimeter (cm)
Milli-
thousandth 10-3
millimeter (mm)
Micro-
millionth
10-6
micrometer (µm)
Nano-
billionth
10-9
nanometer (nm)
 With the unaided eye, you can see down
to about 200 µm (that’s 0.2 mm).
 With a quality light microscope, you can
see something as small as 200 nm clearly
(that’s 0.0002 mm).
 With an electron microscope, you can
visualize something as small as 0.2 nm
clearly (that’s 0.0000002 mm or otherwise
stated, 2x10-7 mm).
Check out: http://www.cellsalive.com/howbig.htm
4 mm
2 mm
200 µm
200 nm
Sizes of Things &
Photomicrography
Check out:
• How Big?
– http://www.cellsalive.com/howbig.htm
• Scale of the Universe
– http://htwins.net/scale2/
• Olympus Bioscapes Competition winners
– http://www.olympusbioscapes.com/gallery/2012/
• Nikon Small World Competition (photo & video)
– http://www.nikonsmallworld.com/
Microscopes: Tools of Biologists
Different microscopes have different advantages and
disadvantages. Biologists use different microscopes
depending upon what they want to look at / observe.
Dissecting Microscope also called a stereo microscope
•________________________:
– 2 eyepieces
objective and ___________
ocular lens(in the eyepiece)
– 2 lenses, __________
– 2 lamps, one above and one below the specimen
– Advantages:
•
•
•
•
Specimen can be alive
No special preparation of specimen needed
Easy to use!
Relatively inexpensive
– Disadvantages:
• Low magnifying power (up to 60x usually)
Compound Light Microscope
• ______________________________
ocular lens (aka eyepiece)
objective and ___________
– 2 lenses, __________
• On student ‘scope, usually have 10x ocular lens & several objective
lenses: 2x (scanning), 10x (low power), & 40x (high power)
water on a slide
– Sample often placed in _______
– Some specimens are stained or “fixed” with dyes -- this
enhances contrast & helps preserve specimen (but kills it too)
– Light passes _________
through sample and is “bent” by lenses to
produce a magnified image
– Advantages:
•
•
•
•
•
Specimen can be alive
Easy specimen preparation
Relatively easy to use
Fairly inexpensive for a basic ‘scope
1000x clearly
Can magnify up to _______
– Disadvantages:
0.2 µm (200 nm)
• Cannot see anything smaller than ______________
(note: a small cell is about 10 µm across)
Modern Optical Microscopes with
Digital Camera attachments
http://www.microscopyu.com/museum/e600pol.html
http://www.microscopyu.com/museum/smz1500.html
Transmission Electron Microscopy
http://en.wikipedia.org/wiki/Transmission_electron_microscopy
http://www.fei.com/products/tem/tecnai/
TEM Specimen Preparation
In TEM, the specimen must be thin enough to allow electrons to
travel through the tissue.
An ultra-microtome slices samples
as fine as 70 nm thin so they can be
viewed in a transmission EM.
You can cut very thin slices of your specimen either by fixing it
in plastic or freezing it. The specimen is cut into thin sections by
a diamond knife in an instrument called ultramicrotome. Each
section is only 50-100 nm thick. A thin section of your sample is
placed on a copper grid and stained with a heavy metal, like
uranium & lead, which scatters electrons well and improves the
contrast in the microscope. The slice of tissue can now be
studied under the electron beam.
Alternately, a solution of isolated material (can be a solution
with bacteria or a solution with isolated molecules) is spread on
a support grid coated with plastic. A solution of heavy metal salt
is added. The metal salt solution does not bind to the material
but forms a "shadow" around it on the grid. The specimen will
appear as a negative picture when viewing it in the TEM.
http://www.eicn.ucla.edu/UTCultramicrotome
http://www.nobelprize.org/educational/physics/microscopes/te
m/preparation.html
http://en.wikipedia.org/wiki/Transmission_electron_microscopy
Scanning Electron Microscopy
http://www.nist.gov/cnst/nanofab/toolset-metrology.cfm
http://en.wikipedia.org/wiki/Scanning_electron_microscope
• Electron Microscopes
• Sends beam of _________
electrons over or through specimen
electromagnets to produce a
– This beam is bent by large _______________
magnified image
There are two main types of electron microscopes:
• _____________
Transmission Electron Microscope (TEM)
– Beam of electrons passes ________
through an ultra-thin section of a
specimen and onto a fluorescent screen or photographic film
– Images produced are ________________
cross-sections of specimens
Scanning Electron Microscope (SEM)
• __________
surface a specimen,
– Beam of electrons passes over the _______of
electrons bounce off at different angles & are “read” to produce
image
3D pictures of the ________
surface of samples (no inside
– Images are ____
views)
TEM
____ Micrographs
Pancreatic cell
Golgi body
http://en.wikipedia.org/wiki/Transmission_electron_microscopy
Bacillus subtilis
bacterium
http://www.histology-world.com/photoalbum/displayimage.php?album=55&pid=509#top_display_media
Herpes virus
Nucleus
surrounded
by rER
Mitochondria
(in lung cells)
http://www.histology-world.com/photoalbum/thumbnails.php?album=55&page=2
____
SEM Micrographs
Hair shaft
Can you
guess what
this is?
Ebola Viruses
(one w/ false color)
The fossilized shell of a
microscopic ocean
animal, magnified 392
times its actual size. The
ancient creature, called
Radiolarian, lived in the
waters off Antarctica and
is now used to study
such things as climate
and ocean circulation.
http://bepast.org/dataman.pl?c=lib&dir=docs/photos/ebola/
What is
this?
http://www.aecom.yu.edu/aif/gallery/sem/sem.htm
White
blood cell
(B-cell)
with
viruses
budding
out of it.
http://www.aecom.yu.edu/aif/gallery/sem/sem.htm
TEM (above) and SEM
(below) of viruses budding
from a mammalian cell
http://www.aecom.yu.edu/aif/gallery/sem/sem.htm
• Electron Microscopes
• Advantages:
viruses and
– Can be used to view smaller things like ________
sub-cellular organelles that cannot be seen with light ‘scopes
_____________________
– Can magnify over 100,000x and allows you to see objects as
0.2 nm
small as _______
• Disadvantages:
– Preparation of specimen can be _________
difficult
Ex) Freezing or embedding in resin, slicing ultra-thin sections
– Cannot view living organisms
– Much more complex & difficult to use/operate than light ‘scope
– Extremely expensive to buy and maintain
black & white images (any color electron
– Only produces ______________
micrographs have false color added afterwards by computer)
Virtual Electron
Microscopy
http://micro.magnet.fsu.edu/primer/jav
a/electronmicroscopy/magnify1/index.
html