Analysis of Cell Components

Question 1

What is magnification

Answer 1

how much bigger the image is than the specimen

Question 2

how is magnification calculated

Answer 2

size of image
————————
size of real object

Question 3

conversion units for magnification

Answer 3

Units | In millimeters
Milimeter (mm) |1mm
Micrometer (um)|0.001mm
Nanometer (nm)|0.000001mm

Question 4

what is resolution

Answer 4

how detailed the image is

Question 5

what are the different types of microscopes

Answer 5

1. Optical (light) microscope
2. Electron microscope

Question 6

Explain the optical microscope

Answer 6

•Uses light to form images
•Maximum resolution of 0.2 micrometer
•Maximum magnification x1500
•Meaning you can see nucleus and somewhat see mitochondria (not with much detail)

Question 7

Explain the electron microscope

Answer 7

•Use electrons to form an image
•Higher resolution of about 0.0002 micrometers (so you can see much smaller objects eg ribosomes)
•Higher magnification at x1,500,000

Question 8

What are the different types of electron microscope

Answer 8

•Transmission electron microscope
•Scanning electron microscope

Question 9

Describe the transmission electron microscope

Answer 9

•Use electromagnets to focus a beam of electrons, which is then transmitted through the specimen
•Denser parts of the specimen absorb more electrons, which make them darker on the image
•Good at non living organisms (only used with thin specimens)

Question 10

Describe the scanning electron microscope

Answer 10

•They scan a beam of electrons across the specimen
•This knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image
•The image you end up with with shows the surface of the specimen and can be 3D
•Can be used on thick specimens
•But give low resolution images

Question 11

Advantages to TEM and SEM

Answer 11

TEM- Give high resolution images, so only show small objects
SEM- Can be used on thick specimens, can be 3D

Question 12

Disadvantages to TEM and SEM

Answer 12

Both- Can only be used on non living specimens
TEM-Can only be used on thin specimens
SEM-Gives lower resolution images than TEM’s

Question 13

Stages to prepare microscope slides

Answer 13

1. Using a pipette drop a small drop of water onto the centre of the slide
2. Then using tweezers place a thin (in order for light to go through it) specimen on top of the water drop
3. Add a drop of stain
4. Add cover slip

Question 14

What are microscope artefacts

Answer 14

What you can see down the microscope that aren’t part of the cell or specimen

Question 15

How do you separate organelles under an electron microscope

Answer 15

cell fractionation

Question 16

Stage of Cell Fractionation

Answer 16

1.Homogenisation- breaking up the cell, the goal is to break up the plasma membrane and release the organelles into solution (using a blender). The solution should also be isotonic (same concentration of chemicals as the cells being broken down, to prevent damage to organelles through osmosis
2.Filtration- getting rid of the big bits, solution should be filtered through a gauze
3.Ultracentrifugation- separating the organelles, homogenize poured into a tube and it’s put into a centrifuge and spun at a low speed. The heavier organelles are flung to the bottom of the tube and the rest (supernatant) is poured out in a separate tube and spun again at a higher speed (repeated until all the organelles are separated out)