Analysis of cell components Flashcards
What is magnification?
How much bigger the image is then the specimen
What is the equation for magnification?
Magnification = size of image / size of real object
What is resolution?
How detailed an image is
What are the conversion between cm to nm
cm x10 = mm
mm x 1000 = um
um x 1000 = nm
Describe an optical (light) microscope
Uses light to form an image
Max resolution = 0.2 micrometres
Max useful magnification = x1500
Describe an electron microscope
Uses electrons to form an image
Max resolution = 0.0002 micrometre (more detailed than light microscopes)
Max useful magnificatin = x1500000
Name the 2 types of electron microscopes
Transmission electron microscopes
Scanning electron microscopes
Describe an transmission electron microscope
Uses electromagnets to focus a beam of electrons through the specimen
Higher resolution
Only use thin specimens
Denser parts of specimens absorb more electrons making them look darker
Describe a scanning electron microscope
Scan a beam of electrons across the specimen knocking of electrons
Shows surface of specimen (3D)
Can use a thick specimen
Lower resolution
What are the 3 stages of cell fractionation?
Homogenisation
Filtration
Ultracentrifugation
What does homogenisation do?
Breaks up plasma membrane and releases organelles into a solution
What should the solution in homogenisation be like and why?
Cold: reduce enzyme activity that breaks down organelles
Isotonic: Sam concentration of chemicals as cells and prevents damage to them through osmosis
Buffer: to maintain pH
Explain what the process of filtration does
Filters any large cell and tissue debris from organelles
Explain the process of ultracentriguation
The solution of organelles is spun in a centrifuge at increasing speeds
Pellet - thick sediment
Supernatant - drained and spun again
Name the organelles from heaviest to lightest
Nucleus
Mitochondria
Lysosomes
Endoplasmic reticulum
Ribosomes
