3.2.1.3 Methods Of Studying Cells

Question 1

What’s cell fractionation the process of

Answer 1

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

Question 2

What does cell fractionation enable

Answer 2

Enables organelles to be studied individually

Question 3

How many steps are there to cell fractionation

Answer 3

3

Question 4

What happens in step 1 of cell fractionation

Answer 4

The cell tissue is homogenised (broken up)

Question 5

How does cell tissue get homogenised

Answer 5

In a blender under 3 very specific conditions

Question 6

What are the 3 conditions for cell homogenisation

Answer 6

Ice cold water
Isotonic solution
Liquid has a buffer

Question 7

What does using ice cold water for cell homogenisation prevent

Answer 7

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

Question 8

What’s isotonic solutions and whys it useful

Answer 8

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

Question 9

What does using an isotonic solution prevent

Answer 9

Organelles swelling/bursting/shrivelling

Question 10

What does the solution being buffered prevent

Answer 10

Prevents/reduces changes in pH

Prevents denaturing of enzymes/proteins/organelles

Question 11

What happens to the water in a cell in hypertonic solution

What happens to the cell

Answer 11

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

The cell shrivels

Question 12

What happens to the water in a cell in hypotonic solution

What happens to the cell

Answer 12

There’s more water outside so water fills the cell

The cell swells + bursts

Question 13

Why can’t you study organelle in hypotonic solution

Answer 13

As it’s too damaged and not repairable

Question 14

What’s step 2 of cell fractionation

Answer 14

The ruptured cells/organelles are filtered

Question 15

What does filtering do in cell fractionation

Answer 15

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

Question 16

What’s step 3 of cell fractionation

Answer 16

Ultracentrifugation

Question 17

What happens in ultracentrifugation

Answer 17

Organelles are spun at high speeds in a centrifuge

Question 18

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

Answer 18

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

Question 19

What do the lighter,smaller organelles form in in ultracentrifugation

Answer 19

The supernatant

Question 20

What happens to the supernatant and the pellet

Answer 20

The supernatant is poured off and the pellet is removed

Question 21

What is found in the pellet first and why

Answer 21

The nucleus

Is the heaviest organelle

Question 22

What 4 organelles do you get next at medium spinning speed

Answer 22

Mitochondria
RER
Plasma membrane
SER

Question 23

What organelles do you get finally at high spinning speed

Answer 23

Free ribosomes

Question 24

What’s magnification

Answer 24

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

Question 25

What’s resolution

Answer 25

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

Question 26

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

Answer 26

200nm

Question 27

What’s the equation for total magnification

Answer 27

Total magnification = objective magnification x eyepiece magnification

Question 28

What are the 2 types of microscope

Answer 28

Light microscope | Electron microscope

Question 29

What’s another name for a light microscope

Answer 29

Optical microscope

Question 30

What’s a light microscopes resolution

Answer 30

200nm

Question 31

How can 2 objects only been seen by light microscope

Answer 31

If light can pass between them

Question 32

4 different magnifications in a light microscope

Answer 32

X4, X10, X40, X100

Question 33

3 advantages of a light microscope

Answer 33

Cheaper Easier to use Can see living specimens

Question 34

2 disadvantages of light microscopes

Answer 34

Limited resolution | Limited magnification

Question 35

What does the condenser lens do

Answer 35

Changes + controls amount of light

Question 36

What do electron microscopes use instead of light

Answer 36

A beam of electrons

Question 37

What’s the resolution like in electron microscopes and why

Answer 37

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

Question 38

What’s an electron microscopes image produced on

Answer 38

A computer screen called a photomicrograph

Question 39

2 advantages of an electron microscope

Answer 39

Higher resolution | Higher magnification

Question 40

3 disadvantages of electron microscopes

Answer 40

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

Question 41

What are the 2types of electron microscopes

Answer 41

Transmission electron microscopes (TEM) | Scanning electron microscopes (SEM)

Question 42

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

Answer 42

dead and thin

Question 43

What happens in a TEM

Answer 43

A beam of electrons is passed completely through a specimen

Question 44

What can the specimen be like in a SEM

Answer 44

It can be thicker

Question 45

What happens in a SEM

Answer 45

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

Question 46

What are TEMs and SEMs both in

Answer 46

Vacuums

Question 47

3 features of a photomicrograph

Answer 47

Grainy Flat 2D B&W

Question 48

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

Answer 48

Condenser electromagnets

Question 49

Why is detail never achieved in TEMs

Answer 49

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

Question 50

Where is the gun placed in a TEM

Answer 50

Above the specimen

Question 51

What’s the photomicrograph produced like from a SEM

Answer 51

3D

Question 52

Does a TEM or SEM have lower resolution?

Answer 52

SEM

Question 53

Where can the gun be in a SEM

Answer 53

Below the specimen

Question 54

2 advantages of a TEM compared to a SEM

Answer 54

Higher resolution | Higher magnification

Question 55

3 disadvantages of a TEM compared to a SEM

Answer 55

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

Question 56

3 advantages of a SEM compared to a TEM

Answer 56

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

Question 57

1 disadvantage of a SEM compared to a TEM

Answer 57

Lower resolution

Question 58

What’s the resolution like in an electron microscope

Answer 58

0.1nm

Question 59

3 disadvantages of an electron microscope

Answer 59

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

Question 60

What are the 2 parts to preparing a specimen

Answer 60

Sectioning | Staining

Question 61

What are specimens embedded in

Answer 61

Was

Question 62

How many m in a km

Answer 62

1000m

Question 63

How many cm in a m | How many mom in a m

Answer 63

100cm | 1000mm

Question 64

How do you get from mm to miceometre

Answer 64

X1000

Question 65

How do you get from mm to mm

Answer 65

X 1,000,000

Question 66

How do u get from nm to mm

Answer 66

/1000000

Question 67

What’s the image equation

Answer 67

Image = actual image x magnification