Transcript 7.1 History and Microscopes

CHAPTER 7
CELL STRUCTURE & FUNCTION
PGS. 168 - 199
CELL STRUCTURE &
FUNCTION
ANTON VAN LEEUWNENHOEK
One of the first
person’s to use
a microscope.
 Looked at pond
water and saw
small organisms.

ROBERT HOOKE
 Looked
at plant
tissues in 1665.
 He specifically
looked at cork.
 Looked like tiny
chambers he
called “cells”
Microscopy Today: Compound Light
Microscope

Light passed through specimen

Focused by glass lenses

Image formed on human retina

Max magnification about 1000X

Resolves objects separated by 0.2 mm, 500X
better than human eye
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Compound Light Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
85 µm
amoeba, light micrograph
eye
ocular lens
light rays
objective lens
specimen
condenser lens
light source
a. Compound light microscope
© Robert Brons/Biological Photo Service
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Microscopy Today: Transmission
Electron Microscope

Abbreviated T.E.M.

Electrons passed through specimen

Focused by magnetic lenses

Image formed on fluorescent screen

Similar to TV screen

Image is then photographed

Max magnification 1000,000sX

Resolves objects separated by 0.00002 mm,
100,000X better than human eye
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Transmission Electron Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
200 nm
pseudopod segment, transmission electron
micrograph
electron source
electron beam
electromagnetic
condenser lens
specimen
electromagnetic
objective lens
electromagnetic
projector lens
observation screen
or
photographic plate
b. Transmission electron microscope
© M. Schliwa/Visuals Unlimited
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Microscopy Today: Scanning
Electron Microscope

Abbreviated S.E.M.

Specimen sprayed with thin coat of metal

Electron beam scanned across surface of specimen

Metal emits secondary electrons

Emitted electrons focused by magnetic lenses

Image formed on fluorescent screen

Similar to TV screen

Image is then photographed
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Scanning Electron Microscope
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
500µm
amoeba, scanning electron micrograph
electron gun
electron beam
electromagnetic
condenser
lenses
scanning coil
final
condenser
lens
secondary
electrons
specimen
electron
detector
TV
viewing
screen
c. Scanning electron microscope
© Kessel/Shih/Peter Arnold, Inc.
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Microscopy and Amoeba proteus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
85 µm
amoeba, light micrograph
eye
ocular lens
light rays
electron source
electron beam
electromagnetic
condenser lens
specimen
electromagnetic
objective lens
objective lens
500µm
200 nm
pseudopod segment, transmission electron
micrograph
amoeba, scanning electron micrograph
electron gun
electron beam
electromagnetic
condenserl
enses
scanning coil
specimen
condenser lens
electromagnetic
projector lens
observation screen
or
photographic plate
light source
a. Compound light microscope
b. Transmission electron microscope
final
Condenser
lens
secondary
electrons
specimen
electron
detector
TV
Viewing
screen
c. Scanning electron microscope
a: © Robert Brons/Biological Photo Service; b: © M. Schliwa/Visuals Unlimited; c: © Kessel/Shih/Peter Arnold, Inc.
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