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3.2 Cells (A Level Biology) > 3.2.1.3 Methods of Studying Cells > Flashcards

3.2.1.3 Methods of Studying Cells Flashcards

1
Q

The 2 main categories for microscopes are…and…

A

Optical
Electron

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2
Q

The 2 main types of electron microscopes are… and…

A

Scanning
Transmission

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3
Q

True or false, you can view living specimen with electron microscopes

A

False
(You can only view non- living specimen however you can view living specimen with the optical microscope)

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4
Q

The 2 types of microscope that produce a 2D image of the specimen are the…and…microscope

A

Optical
Transmission

(Think Oti is 2D)

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5
Q

The …microscope produces a 3D image of the specimen

A

Scanning electron microscope

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6
Q

Sometimes when you are looking at a prepared sample under the microscope you can see things that aren’t actually part of the specimen e.g dust/ air bubbles/ fingerprints. These are known as…

A

Artefacts

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7
Q

Artefacts occur during the…of the sample

A

Preparation

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8
Q

The occurrence of artefacts can be decreased by more…preparation of the sample

A

Careful

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9
Q

Artefacts are common in the…microscope due to the lengthy treatment required to prepare samples

A

Transmission electron

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10
Q

Artefacts are common in the electron transmission microscope due to…

A

The lengthy treatment required to prepare samples

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11
Q

A longer wavelength leads to a …resolution

A

Lower
(Which is why optical microscopes have a lower resolution as the wavelength of light is relatively long)

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12
Q

Resolving power is the same thing as…

A

Resolution

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13
Q

Resolution is the same thing as…

A

Resolving power

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14
Q

An advantage of electron microscopes (both scanning and transmission) over optical microscopes is that they have a very powerful/ high…

A

Resolution

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15
Q

Under electron microscopes specimen can sometimes be seen in colour due to…colour

A

False

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16
Q

Resolution is the…distance that points can be separated and still be seen as…items

A

Smallest
Separate

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17
Q

On an optical microscope which is higher out of the coarse focus and fine focus

A

Coarse focus= above
Fine focus= below

(As C comes before F in alphabet)

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18
Q

As well as microscopy, another method of studying cells is…

A

Fractionation
(Isolating individual organelles within the cell to study)

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19
Q

As well as microscopy, another method of studying cells is…

A

Fractionation
(Isolating individual organelles within the cell to study)

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20
Q

Cell fractionation is the process where cells are…

A

Broken up (lysed) and the different organelles within the cells are released then separated out

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21
Q

Before cell fractionation can begin, the tissue is placed into a cold, buffered solution with the same water potential as the tissue known as the…

A

Isolation medium

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22
Q

The isolation medium is cold so that…

A

enzyme activity is kept low to prevent hydrolytic enzymes from damaging organelles

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23
Q

The isolation medium is cold to keep enzyme activity low and to prevent…enzymes from damaging organelles

A

Hydrolytic

24
Q

The isolation medium is buffered to keep the…stable to prevent the enzymes and proteins from becoming denatured or damaged

A

pH

25
Q

The isolation medium has the same water potential as the tissue to make sure that…

A

Water doesn’t leave or enter the organelles by osmosis so they don’t swell or shrink

26
Q

The first stage of fractionation is…, the second stage is…and the 3rd stage is…

A

Homogenisation
Filtration
Ultracentrifugation

27
Q

Homogenisation breaks up the cells within the tissue to release the organelles from the cells and is done with a ….

A

Blender/ homogeniser
(Or pestle and mortar)

28
Q

The fluid (‘soup’) obtained from homogenisation is called the…

A

Homogenate

29
Q

In fractionation after homogenisation the homogenate (fluid (‘soup’) obtained is filtered to remove any…

A

Debris (whole cells or large bits of remaining tissue)

30
Q

Ultracentrifugation is where the fragments (organelles) in the filtered homogenate are…

A

Separated in a centrifuge at increasing speeds (based on their size, mass and density)

31
Q

…. centrifugation means repeating the process of centrifugation but increasing the speed each time

A

Differential

32
Q

Centrifugation separates cell components based on … and…

A

Size
Density

33
Q

In centrifugation the larger and denser components/ organelles form a…at the bottom of the tube

A

Pellet

34
Q

In centrifugation, the smaller and less dense components/ organelles remain in suspension above the pellet (denser and larger components/ organelles) which is known as the…

A

Supernatant

35
Q

The stage micrometer is used to c…the eyepiece graticule

A

Calibrate

36
Q

Optical microscopes use…to form an image

A

Light

37
Q

Electron microscopes (both scanning and transmission) use…to form an image

A

Beams of electrons

38
Q

Which organelles can be viewed under an optical microscope

A

Nucleus, cell-surface membrane, cell wall, vacuole, chloroplasts
Cytoplasm (although not technically an organelle)

(Sometimes mitochondria can be seen but not always)

39
Q

Which organelles can’t be viewed under an optical microscope as they’re too small

A

Ribosomes
Lysosomes
Endoplasmic reticulum

(These are the key ones but sometimes other organelles can’t be seen either)

40
Q

What unit do we mostly use to measure plant and animal cells with

A

Micrometers
(Always convert to this when calculating the length of the cell unless the question says otherwise)

41
Q

For transmission electron microscopes, what do darker parts of the image mean

A

The specimen is denser in this area so more electrons are absorbed and the image appears darker here

42
Q

For an image produced by a transmission electron microscope, how can you tell which parts of the cell are denser

A

They’re darker as more electrons are absorbed

43
Q

How were the first scientists to use electron microscopes able to distinguish between artefacts and organelles

A

They repeatedly prepared the specimen in different ways
If an object could be seen with one preparation technique but not another then it was more likely to be an artefact than an organelle

44
Q

Resolution is…

A

The smallest distance that points can be separated and still be seen as separate items

45
Q

Magnification is…

A

How much bigger the image is compared to the actual size of the object

46
Q

A difference between optical microscopes and electron microscopes is that with…microscopes the image is viewed in colour but in… microscopes the image is viewed in black and white

A

Optical= colour
Electron (both transmission and scanning)= black and white

47
Q

A difference between optical microscopes and electron microscopes is that …microscopes can be used to view living specimen but…microscopes can only be used to view non living specimen

A

Optical= living
Electron (both scanning and transmission)= non living (because the specimen is placed in a vacuum)

48
Q

With electron microscopes (both transmission and scanning) you can only view non living specimen as the specimen is placed in a…

A

Vacuum

49
Q

True or false, both optical microscopes, transmission electron microscopes and scanning electron microscopes need thin specimen

A

False
Scanning electron microscopes don’t require a thin specimen (but the other 2 do)

50
Q

Which has a higher resolution out of TEMs or SEMS

A

TEMs
(But both types of electron microscopes still have a higher resolution than optical microscopes)

51
Q

Which has a higher resolution out of TEMs or SEMS

A

TEMs
(But both types of electron microscopes still have a higher resolution than optical microscopes)

52
Q

The tube containing the homogenate has been placed in the centrifuge at a low speed to form the pellet with the supernatant on top. Which out of the pellet and supernatant gets removed from the tube so that it can be placed at the centrifuge at an even higher speed than before

A

Supernatant

(The supernatant is drained off and poured into another tube to then be placed in the centrifuge at a faster speed so that the pellet containing the denser/ larger organelles stays in the tube)

53
Q

When placing the homogenate in the centrifuge containing plant cells, what order would you expect the organelles to separate out in. (Remember, the first pellet formed contains the most dense and largest organelles)

A

Nuclei, chloroplasts, mitochondria, lysosomes, endoplasmic reticulum, ribosomes,

(Naughty Clever Monkeys Like Eating Raspberries)

54
Q

Stages for preparing temporary mount for a piece of plant tissue

A

1) Use pipette to add one drop of water to the slide
2) Cut thin specimen of plant tissue using scalpel and place on top of water on slide
3) Add drop of potassium in potassium iodide to stain the starch granules blue/ black
4) Use a mounted needle to carefully lower the cover slip onto the specimen

55
Q

When calibrating the eyepiece graticule using the stage micrometer, they both need to be at the same…

A

Objective lens power

3.2 Cells (A Level Biology) (5 decks)

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