Analysis of Cell Components 2A Flashcards
Define magnification
How much bigger the image is than the specimen
Define resolution
How well a microscope distinguishes between two points
Optical microscopes
Use light to form an image
Max resolution of 0.2 um
Max magnification of x1500
Electron microscopes
Use electrons to form an image
Higher resolution than optical microscopes
Max resolution of 0.0002 um
Max useful magnification of x150000
Transmission electron microscopes
Use electromagnets to focus a beam of electrons, denser parts absorb more electrons making them darker
Give a high resolution
Can only be used on thin specimens
Scanning Electron Microscopes
Scan a beam of electrons across the specimen, this knocks off electrons from the specimen to form an image
Can be 3D images
Can be used on thick specimens
They give lower resolution images than SEM’s
What is homogenisation
Breaking up the cells by vibrating the cells this breaks the cell membrane and releases the organelles into solution. Solution must be kept ice cold and be isotonic - same amount of chemicals as the organelles being broken down. A buffer should be added to maintain PH
What is filtration
Filtering the cell components through a gauze to separate any large debris from the organelles
What is ultracentrifugation
Separating the organelles
1. Cell fragments poured into a tube and put into a centrifuge. The heaviest organelles are flung to the bottom and form a sediment the rest of the organelles are suspended the fluid above the sediment - the supernatant
2. The supernatant is drained off into another tube and spun at a higher speed, again the heaviest organelles this time the mitochondria form a pellet at the bottom of the tube then the rest is drained off and spun at an even higher speed. The process is repeated until all the organelles are separated
