Cycling of Matter in Living Systems

1.3 Developments in Imaging Technology and Staining Techniques

Contrast

Scientist discovered that they could manipulate the light source to alter the contrast between structures in the cell and improve the image.

Experiments with stains and coloring agents showed that particular stains could attach to particular parts of the cell, improving the contrast between internal structures and producing better images

A disadvantage to staining is that it kills the cells making it impossible to view living cells.

Microscopes

We are going to be looking at 4 types of microscopes:– Light Microscopes– Electron Microscopes

TEM SEM

– Confocal Laser Scanning Microscope– Scanning Tunneling Microscope

Light Microscope

Think of the compound microscope as a good friend

It is relatively inexpensive, reliable, but it has its limitations.

Maximum magnification ~400X

Electron Microscopes

The “go to” reliable microscope with lots of power, and just a hint of mystery

Engineered in the 1930s. Specimens are illuminated with a beam of electrons instead of light. Makes electron micrograph.

Transmission Microscope

Works like a slide projector. Electrons go through a thin sample to give the micrograph

Magnifies 1 500 000X

Scanning Electron Microscope

Sweeps a beam of electrons over object to get a 3D image.

Magnification of up to 300,000x

Confocal Laser Scanning Microscope

Has very powerful observation abilities Invented in the 1960s. Can study thick specimens, measures 2D

slices in order to form a 3D image.

Scanning Tunneling Microscope

Very technologically advanced. It seems like it can do ANYTHING.

Developed in the 1980s, can obtain an image of atoms on an object’s surface. Can produce images of DNA. Uses an electron probe to make a 3D image

Homework: Read Section 1.3 and complete pg 262 1.3 Check & Reflect, #1-6