Cells

Question 1

Magnification

Answer 1

How many times larger the image is compared to object

Question 2

Resolution

Answer 2

Minimum distant between two objects in which they can still be viewed as separate

Question 3

Optical microscope

Answer 3

Beam of light is condensed to create an image
Poorer resolution due to light having a longer wavelength
Lower magnification
Colour images
Can view living samples

Question 4

Electron microscope

Answer 4

A beam of electrons is condensed to create an image .Electromagnets are used to condense the beam

Higher resolving power as electrons have shorter wave length
Higher magnification
Black and white images
Sample must be in vacuum
Non living

Question 5

Transmission electron microscope

Answer 5

Extremely thin specimens are stained and placed in a vacuum.
Electron gun produces a beam of electrons that pass through the specimen.
Some absorbs the electrons appear darker .
Image produced 2D and shows detailed images on internal structure of cell

Question 6

Scanning electron microscope

Answer 6

The specimen does not need to be thin as electrons are not transmitting through . Electrons beamed onto the surface and the electrons are scattered diff ways depending on the contours .
3D image produced

Question 7

Magnification calculations

Answer 7

I= AxM
M= A/M
Image and actual Have to be same unit

Question 8

Units

Answer 8

Metre to mm x1000
Mm to micrometer x1000
Micrometer to mm / 1000

Question 9

Cell fractionation

Answer 9

Cells are broken open to release the contents and organells are then seperated

Cells must be in a cold isotonic and buffered solution

Cold : to reduce enzyme activity . When you break open enzymes released which could damage organells
Isotonic: must be same water potential to prevent osmosis as this could cause organells to burst
Buffered : the solution has a ph buffer to prevent damage to organells

Question 10

Homogenisation and unltracentrigfugation

Answer 10

Step 1 : break open cells blender solution is cold isotonic buffered
Filter to remove large debris

Step 2 : filer solution is spun at diffrent speed in centrifuge
Organelles separate according to their densities

Question 11

Differential centrifugal ion

Answer 11

Centrifuge spins and the centrifuge forces causes pellets of the most dense organelles to form a bottom

Centrifuge is spun at a low speed and the process is repeated at increasingly faster speeds

Each time super stand is removed leaving behind pellet of oragnelles

Question 12

Order of density of organells

Answer 12

Nuclei
Chloroplasts
Mitochondria
Lysosomes
Endopplasmic reticulum
Ribosomes