Cells

Question 1

Isolation of cell organelles

Answer 1

Cell homogenisation to break open cells
Filter to remove whole cells
Use isotonic solution to prevent osmotic damage to organelles Cold to prevent damage of organelles by enzymes
Buffer to prevent protein and enzyme denaturation
Centrifuge at lower speed to separate nuclei
Re-spin supernatant (after nuclei pellet removed) at higher speed Mitochondria in pellet
Re-spin supernatant at higher speed
Ribosomes in pellet

Question 2

Electron microscope how?

Answer 2

Can see organelle structure
Electrons pass through/over specimen
Denser parts absorb more electrons and appear dark Electrons have short wavelength so give high resolution High magnification

Question 3

Electron microscope limitations

Answer 3

Cannot look at living material as in a vacuum Specimen must be very thin
Preparation may create artefacts
Does not produce a coloured image Complex staining method

Question 4

Scanning electron microscope

Answer 4

3D images

Question 5

Transmission electron mircroscope

Answer 5

2D image

Question 6

Facilitated diffusion

Answer 6

Large, polar molecules go through channel/carrier proteins