Analysis Of Cell Componenets Flashcards
What is magnification?
How much bigger the image is than the specimen
What is the formula for magnification?
Size of image ÷ size of real object
How do you convert nanometres into micrometers?
÷1000
How do you convert micrometres into millimetres?
÷1000
What is the resolution?
How well a microscope distinguishes between 2 points that are close together
What are the 2 types of microscope?
Optical
Electron
What are optical microscopes?
Use light to form an image
What is the maximum resolution of an optical microscope?
0.2 micrometers
What is the maximum useful magnification of an optical microscope?
x1500
What can you see with an optical microscope?
Mitochondria
Nucleus
What are electron microscopes?
Use electrons to form an image
What is the maximum resolution of an optical microscope?
0.0002 micrometers
What is the maximum useful magnification of an electron microscope?
x1 500 000
What are the 2 types of electron microscope?
Transmission
Scanning
What are transmission electron microscopes?
Use electromagnets to focus a beam of electrons which is then transmitted through the specimen
Why do denser parts of the specimen look darker on the image?
Absorb more electrons
What are the advantages of TEMs?
Give high resolution images so can see internal structures of organelles
What is are the disadvantages of TEMs?
Have to view specimen in a vacuum so cannot look at living specimens
Only used on thin specimens
What are scanning electron microscopes?
Scan a beam of electrons across a specimen which knocks of electrons from specimen which are gathered in a cathode ray tube to form an image
What are the images like in SEMs?
Show surface of specimen
Can be 3D
What is an advantage of SEMs?
Can be used on thick specimens
What is a disadvantage of SEMs?
Give lower resolution images than TEMs
What is cell fractionation?
Separating organelles from the rest of the cell
What are the 3 steps of cell fractionation?
Homogenisation
Filtration
Ultracentrifugation
What does homogenisation do?
Breaks up plasma membrane and releases organelles into solution
2 ways of homogenisation?
Vibrating cells
Grinding cells in a blender
What are the 3 conditions for homogenisation?
Ice cold
Isotonic solution
Buffer solution
Why must the solution be kept ice cold in homogenisation?
To reduce enzyme activity
Why must the solution be isotonic?
Prevents damage to organelles though osmosis
What does an isotonic solution mean?
Same concentration of chemicals as the cells being broken down
What does the buffer solution do?
Maintains the pH
What happens after the cell solution is homogenised?
Filtered through gauze to separate any large cell debris or tissue debris
What is left after filtration?
A solution containing a mixture of organelles
How can you separate a particular organelle from all the others?
Ultracentrifugation
What is the process of ultracentrifugation?
Cell fragments poured into tube
Tube put in centrifuge and spun at low speed
Supernatant reined off into another tube and spun at a higher speed in centrifuge
Process repeated at higher speeds until all organelles are separated out
Why is the solution spun in a centrifuge?
To separate heavies organelles from lightest
What happens to the heaviest organelles in ultracentrifugation?
Form a thick sediment called a pellet at bottom of tube
