Block A Flashcards
Cellular Structure and function
who was the founder of cells and what was used?
Robert Hooke
He found out from a bark of a tree where it was made of small blokes which are cells
What is cell theory
- forms the building block of all living organisms
- Arise through the division of existing cells
- Contain information for inheritance
- site of metabolism
- Capable of independent life
What are microscopes
provide a magnified image of something
Magnification
Is the apparent increase size
Total Magnification
Magnification of ocular x magnification of an objective
Unit of measures
milli mm = 10-3 meters
micro um= 10-6 meters
nano nm = 10-9 meters
1 um is 1 micron
Size of object
Size of image / Magnification
Resolution
Ability to show 2 objects as separate is called the resolution
it is limited by the wavelength of light
Resolving Power
R= 1.22 x wavelength / 2n x sintheta
Light microscopy
unstained live cells
phase contrast
Optical modification make denser structure appear darker
Differential interference contrast microscopy
Similar to phase contrast to view internal structure
Fluorescent Microscopy
stained dead cells
enable specific structures to be seen
Dyes have natural affinity for specific structure
Bound to antibodies
Standard wide-field
Uses fluorescent antibodies that bind particular cellular protein.
Confocal
lasers that shows different points in a sample then processed by computer to give focal plane.
Electron Microscopes
Use beam of electrons than light
wavelength is smaller than light
greater resolving power than light
helps to understand viruses
Transmission electron microscopes
used to study the fine detail of internal structure
Scanning electron microscopes
Study fine detail of the surface of cells
Disadvantage of transmission electron microscopes
can only examine dead things
stained with heavy metal
expensive to buy and maintain
Atomic Force Microscopy
Measure hardness of a surface to a fraction of nanometer scale.
Advantage of atomic force
No need to coat
less chance of artifacts
Can study living organisms
Can be combined with other microscopy
Disadvantage of atomic force
Cannot scan a wide area
Take longer time
