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Biology - biological molecules + cells > 3.2.1.3 Methods Of Studying Cells > Flashcards

3.2.1.3 Methods Of Studying Cells Flashcards

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1
Q

What’s cell fractionation the process of

A

The process where a cell is ruptured (membrane/cell wall burst open)

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2
Q

What does cell fractionation enable

A

Enables organelles to be studied individually

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3
Q

How many steps are there to cell fractionation

A

3

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4
Q

What happens in step 1 of cell fractionation

A

The cell tissue is homogenised (broken up)

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5
Q

How does cell tissue get homogenised

A

In a blender under 3 very specific conditions

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6
Q

What are the 3 conditions for cell homogenisation

A

Ice cold water
Isotonic solution
Liquid has a buffer

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7
Q

What does using ice cold water for cell homogenisation prevent

A

Prevents enzyme activity that might damage organelles - prevents cells from being hydrolysed (broken down)
Prevents organelles from reacting with each other

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8
Q

What’s isotonic solutions and whys it useful

A

It has the same water potential as organelles so prevents osmosis into organelles

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9
Q

What does using an isotonic solution prevent

A

Organelles swelling/bursting/shrivelling

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10
Q

What does the solution being buffered prevent

A

Prevents/reduces changes in pH

Prevents denaturing of enzymes/proteins/organelles

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11
Q

What happens to the water in a cell in hypertonic solution

What happens to the cell

A

There’s more water in the cell so the water leaves it

The cell shrivels

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12
Q

What happens to the water in a cell in hypotonic solution

What happens to the cell

A

There’s more water outside so water fills the cell

The cell swells + bursts

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13
Q

Why can’t you study organelle in hypotonic solution

A

As it’s too damaged and not repairable

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14
Q

What’s step 2 of cell fractionation

A

The ruptured cells/organelles are filtered

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15
Q

What does filtering do in cell fractionation

A

Removes any debris (unwanted) that aren’t required for the study

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16
Q

What’s step 3 of cell fractionation

A

Ultracentrifugation

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17
Q

What happens in ultracentrifugation

A

Organelles are spun at high speeds in a centrifuge

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18
Q

In ultracentrifugation, what size organelle falls to the bottom of the tube first and why

A

Largest + heaviest organelles fall to the bottom first forming a pellet as spinning organelles increases gravitational pull

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19
Q

What do the lighter,smaller organelles form in in ultracentrifugation

A

The supernatant

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20
Q

What happens to the supernatant and the pellet

A

The supernatant is poured off and the pellet is removed

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21
Q

What is found in the pellet first and why

A

The nucleus

Is the heaviest organelle

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22
Q

What 4 organelles do you get next at medium spinning speed

A

Mitochondria
RER
Plasma membrane
SER

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23
Q

What organelles do you get finally at high spinning speed

A

Free ribosomes

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24
Q

What’s magnification

A

How much bigger a sample appears to be under the microscope than it is in real life

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25
Q

What’s resolution

A

The ability to distinguish between 2 points on an image (amount of detail)

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26
Q

What small distance apart means 2 objects can be see as 1

A

200nm

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27
Q

What’s the equation for total magnification

A

Total magnification = objective magnification x eyepiece magnification

28
Q

What are the 2 types of microscope

A

Light microscope

Electron microscope

29
Q

What’s another name for a light microscope

A

Optical microscope

30
Q

What’s a light microscopes resolution

A

200nm

31
Q

How can 2 objects only been seen by light microscope

A

If light can pass between them

32
Q

4 different magnifications in a light microscope

A

X4, X10, X40, X100

33
Q

3 advantages of a light microscope

A

Cheaper
Easier to use
Can see living specimens

34
Q

2 disadvantages of light microscopes

A

Limited resolution

Limited magnification

35
Q

What does the condenser lens do

A

Changes + controls amount of light

36
Q

What do electron microscopes use instead of light

A

A beam of electrons

37
Q

What’s the resolution like in electron microscopes and why

A

Higher resolution

As electrons have shorter wavelengths than light so we can see cell ultrastructure in much more detail

38
Q

What’s an electron microscopes image produced on

A

A computer screen called a photomicrograph

39
Q

2 advantages of an electron microscope

A

Higher resolution

Higher magnification

40
Q

3 disadvantages of electron microscopes

A

Expensive
Heavy machinery
Electrons can’t see living cells as they get easily distracted/cell interaction (only cell tissue)

41
Q

What are the 2types of electron microscopes

A

Transmission electron microscopes (TEM)

Scanning electron microscopes (SEM)

42
Q

What’s the specimen got to be like in a TEM

A

dead and thin

43
Q

What happens in a TEM

A

A beam of electrons is passed completely through a specimen

44
Q

What can the specimen be like in a SEM

A

It can be thicker

45
Q

What happens in a SEM

A

Electrons are directed at the specimen creating an image from the electrons that are reflected off the surface

46
Q

What are TEMs and SEMs both in

A

Vacuums

47
Q

3 features of a photomicrograph

A

Grainy
Flat
2D
B&W

48
Q

What is used to focus the beam onto the specimen in TEMs

A

Condenser electromagnets

49
Q

Why is detail never achieved in TEMs

A

Due to human error e.g staining/cutting thinly during preparation

50
Q

Where is the gun placed in a TEM

A

Above the specimen

51
Q

What’s the photomicrograph produced like from a SEM

A

3D

52
Q

Does a TEM or SEM have lower resolution?

A

SEM

53
Q

Where can the gun be in a SEM

A

Below the specimen

54
Q

2 advantages of a TEM compared to a SEM

A

Higher resolution

Higher magnification

55
Q

3 disadvantages of a TEM compared to a SEM

A

Image is 2D, B+W, grainy + flat
Have to be thin
Full detail never achieve (human error)

56
Q

3 advantages of a SEM compared to a TEM

A

3D images
Gun can be below
Doesn’t have to be thin

57
Q

1 disadvantage of a SEM compared to a TEM

A

Lower resolution

58
Q

What’s the resolution like in an electron microscope

A

0.1nm

59
Q

3 disadvantages of an electron microscope

A

Artefacts e.g air bubbles
Expensive
Vacuum needed
Skill + training needed

60
Q

What are the 2 parts to preparing a specimen

A

Sectioning

Staining

61
Q

What are specimens embedded in

A

Was

62
Q

How many m in a km

A

1000m

63
Q

How many cm in a m

How many mom in a m

A

100cm

1000mm

64
Q

How do you get from mm to miceometre

A

X1000

65
Q

How do you get from mm to mm

A

X 1,000,000

66
Q

How do u get from nm to mm

A

/1000000

67
Q

What’s the image equation

A

Image = actual image x magnification

Biology - biological molecules + cells (16 decks)

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