Microscopes and separating cell components

Question 1

What is the magnification

Answer 1

The degree to which an object is magnified (How many times bigger the image is)

Question 2

What is the resolution
and What microscope has the higher resolution and why

Answer 2

resolution = Ability to distinguish between two points (Dependent ton the wavelength of the radiation used to view to object)
Electron microscopes electron beam have a smaller wavelength so it has a higher resolution than the light microscopes light beam

Question 3

properties of a transmission electron microscope

Answer 3

• Specimens cant be alive must be viewed in a vacuum
• specimens must be thin and stained
• parts of the specimen absorbs the beam of electrons appearing darker than parts that don’t.
• Resolving power 0.1nm
• Artifacts may appear - part of the micrograph but not part of the natural object. Results from preparation process

Question 4

Properties of a scanning electron microscope

Answer 4

• electrons don’t penetrate the specimen, so the sample doesn’t need to be thin
• The electrons are scattered by the sample, allowing a 3d image to be formed
• Resolving power is 20nm

Question 5

what is the first step on separating cell components

Answer 5

• Broken cells/tissues are placed in a cold, buffered, isotonic solution
• Then put in a homogeniser

Question 6

why are the cells/tissue put in cold, buffered, isotonic solution

Answer 6

cold = stopping enzyme reactions
buffered = keeps PH neutral and means the enzymes don’t denature and keeps the membrane
isotonic = same water concentration meaning no osmosis

Question 7

what happens in the 2nd stage of separating cell components

Answer 7

the homogenate is filtered to remove unbroken cells and then be placed in a centrifuge on a low speed

Question 8

what happens in the 3rd stage of seperating cell components

Answer 8

Once the centrifuge has stopped the denser organisms will go to the bottom of the tubes becoming pellets
- the supernatant is removed and re-spun at a higher speed
repeat at higher speeds

Question 9

What is the order of density and how many times the supernatant will have to be centrifuged

Answer 9

• nuclei
• mitochondria and chloroplast
• lysosomes
• endoplasmic reticulum

Question 10

Why do the specimens need to be in a vacuum, thin and stained for a transmission microscope

Answer 10

Vacuum- electrons are absorbed by air
Thin- so the electrons can pass through
Stained - because the image is black and white

Question 11

How do you convert millimetres into micrometres and vise versa

Answer 11

mm into um = x1000
um into mm = /1000