There are about 90 million rod cells in the human retina, and each contains about 4x107 molecules of rhodopsin that are very densely packed in the membrane disks.

TLS Online TPP Program

#Id: 4462

#Unit 13. Methods in Biology

Scanned-probe microscopy is of two types:

Scanning tunneling microscopy

Atomic force microscopy

TLS Online TPP Program

#Id: 4463

#Unit 13. Methods in Biology

Scanning tunneling microscopy- uses thin metal (tungsten) probe that scans specimen revealing the bumps and depressions of the atoms on the surface of the specimen

TLS Online TPP Program

#Id: 4464

#Unit 13. Methods in Biology

In an atomic force microscope imaging of the surface is done based on modulation of interaction forces between two atoms.

TLS Online TPP Program

#Id: 4465

#Unit 13. Methods in Biology

Cryoelectron microscopy allows examination of hydrated, unfixed, and unstained specimens in the TEM by maintaining them at -196oC (liquid nitrogen).

TLS Online TPP Program

#Id: 4466

#Unit 13. Methods in Biology

This method has been used to generate models of ribosomes, the muscle calcium pump, and 3-D structure of a poliovirus capsid.

TLS Online TPP Program

#Id: 4467

#Unit 13. Methods in Biology

The total magnification is a product of the magnification of the individual lenses.

Total magnification= 40X*10X