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Advanced Higher Biology > Unit 1 - section 1 > Flashcards

Unit 1 - section 1 Flashcards

1
Q

Name 2 things that can be intrinsically harmful when working in a lab.

A

Chemicals

Organisms

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2
Q

Who or what is at risk in a lab?

A

People
Other organisms
Environment

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3
Q

Name the control measures

A 
Elimination
Substitution
Isolation
Education 
Personal protective equipment
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4
Q

Describe elimination

A

The hazardous chemical/ organism is replaced with a less harmful equivalent or the step is removed from the protocol

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5
Q

Describe substitution

A

If the hazard is very particular to a chemical/ organism involved it may be possible to use alternatives which do not produce the same level of risk

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6
Q

Describe isolation

A

The procedure would be carried out in a contained environment

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7
Q

Describe education (control measure)

A

People would be trained to follow standard methods of practice that reduce the risk

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8
Q

Describe personal protective equipment

A

Can include wearing a lab coat, dust mask, gloves etc

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9
Q

What is the purpose of risk assessments?

A

To enable any hazards to be identified and ensure appropriate safety is in place to minimise the risk. Ensures working conditions are safe.

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10
Q

What are burettes used for?

A

For titration. Can make accurate measurements of small volumes

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11
Q

What are pipettes used for?

A

Less accurate than other methods. Bulb is depressed before insertion into the liquid and then gently (almost fully) released

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12
Q

What are syringes used for?

A

Very accurate method of measurement

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13
Q

What are autopipettes used for?

A

Allow w small volumes of liquid to measures very accurately. A disposable tip is used to prevent contamination

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14
Q

What are measuring cylinders used for?

A

Measuring volumes between 5 and 2000cm3. Scale is read from the bottom of the meniscus

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15
Q

Define the term dilution

A

To make a solution less concentrated by adding another solution or water

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16
Q

Formula for dilution calculations

A

V1C1=V2C2

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17
Q

Describe log dilution

A

Performed using a variety of chemicals or microorganisms.
Involves dilution by 1/10 each time
Useful when culturing microbes

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18
Q

Describe linear dilution

A

Involves even quantity separations

Useful for standard curves

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19
Q

What is a standard curve and what is it used for?

A

A graph of known concentrations that allows you to determine unknown concentrations

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20
Q

How can pH be controlled in an experiment?

A

By adding a buffer solution

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21
Q

2 ways pH can be tested

A

PH meter

Universal indicator and a colour chart

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22
Q

Describe the process of centrifugation

A

Used to separate substances by their density.

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23
Q

Define the terms pellet and supernatant

A

Pellet- solid that’s forms at the bottom of the vessel as the machine spins
Supernatant- the remaining liquid

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24
Q

How are the pellet and supernatant formed during centrifugation

A

As the material is rotated in the centrifuge tube the resulting g-force causes the constituents to separate

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25
Q

Name the 3 types of chromatography

A

Paper
Thin-layer
Affinity

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26
Q

Describe paper chromatography

A

Amino acids with different solubilities travel different distances up the paper support

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27
Q

Describe thin-layer chromatography

A

Amino acids with differing solubilities travel different distances up the solid support eg glass/ plastic coated in gel

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28
Q

Describe affinity chromatography

A

Separating biochemical mixtures based on a highly specific interaction. The molecules that are to be separated will bind to the equipment, which will be designed to only attract that substance.
Example interactions- antigen and antibody, enzyme and substrate, receptor and ligand

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29
Q

2 types of molecules that can be separated using chromatography

A

Amino acids

Proteins

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30
Q

What is responsible for the separation of molecules on chromatography

A

Paper and thin-layer chromatography- solubility

Affinity chromatography- affinity for specific antibody or ligand

31
Q

Define electrophoresis

A

Proteins are put in a gel with opposite charges at either end. The charges cause the proteins to move different distances depending on their charge and polypeptide chain length

32
Q

2 factors that affect the migration of molecules in the gel (electrophoresis)

A

By charge or size

33
Q

What molecules can electrophoresis be used to separate?

A

Proteins

34
Q

How can electrophoresis be used to separate molecules in solution?

A

?

35
Q

How can pH be used to separate proteins/amino acids

A

Through iso-electric focusing
Gel set up with pH gradient. Protein/amino acid will migrate until it reaches the pH where it has an overall neutral charge. Since proteins/amino acids carry a charge but have no charge at specific pH they stop at specific points in the gel allowing them to be identified

36
Q

What happens to amino acids when the overall charge is neutral? (iso-electric focusing)

A

Amino acids precipitate out of solution

37
Q

Define iso-electric point

A

pH at which the amino acid precipitates out of solution

38
Q

What are antibody techniques used to detect?

A

Proteins

39
Q

Feature of antibodies that make them suitable to use to detect proteins

A

Antibodies bind to specific antigens so specific proteins can be targeted

40
Q

Define immunoassay

A

Based on antibody and antigen binding principles. ????

41
Q

Describe the process of direct ELISA to detect specific antigens

A

Protein sample added to multi-well plate. Proteins adhere to sides of well
Well washed out to remove non-adhered proteins
Specific antibody for the protein of interest is labelled with a reporter enzyme
Antibody attaches to protein of interest
Well washed out to remove non-adhered antibodies
Substrate added and enzyme causes colour change which identifies presence of specific protein
The deeper the colour, the higher the concentration of specific protein

42
Q

Describe the process of indirect ELISA to detect specific antigens

A

Protein sample added to multi-well. Proteins adhere to sides of well
Well washed out to remove no-adhered proteins
Specific primary antibody added and attached to specific protein
Secondary antibody which has a reporter enzyme attached, is added to plate
Labelled antibody attaches to the primary antibody
Well washed out to remove non-adhered antibodies
Substrate added and enzyme causes colour change which identifies presence if specific protein
The deeper the colour,the higher the concentration of the specific protein

43
Q

Describe the process of capture ELISA to detect specific antigens

A

Antibody that binds to target protein is added to multi-well plate
Well is washed to remove excess antibody
Protein sample added to multi-well plate
Well washed out to remove non-adhered proteins
Second antibody is added which attaches to target protein
Another antibody that is labelled with a reporter enzyme is added
Labelled antibody attaches to second antibody
Well washed out to remove non-adhered antibodies
Substrate added and enzyme causes colour change which identifies presence of specific protein
The deeper the colour, the higher the concentration of specific protein

44
Q

What is the role of reporter enzymes in immunoassays?

A

To catalyse a colour change reaction that is used to detect and quantify the presence of a specific antigen.
If the antigen is present the antibody binds allowing the reporter enzyme to produce a coloured product. (Visual confirmation of the antigens presence)

45
Q

What is a way antibodies can be labelled for detection

A

With fluorophore or a reporter enzyme

46
Q

Describe the process of protein blotting

A

Protein samples are added to well on electrophoresis gel
Electric current used to separate proteins based on charge or size
Separated proteins are blotted onto a membrane
Membrane treated with fluorescently labelled antibodies that bind to a specific target protein
Membrane passed under UV light. Bound antibodies containing fluorophore fluorescence identifying if target protein is present in sample

47
Q

Describe the use of immunohistochemical staining

A

Tissue sample is taken usually from a biopsy
Tissue is stained using a solution that contains labelled antibodies that are specific to a target protein. The label can be a fluorophore or a reporter enzyme
Tissue is washed to remove and unbound antibodies
Substrate added for enzyme that causes colour change or cell sample assessed under UV light. Colour change or fluorescence can be used to identify the presence of target protein

48
Q

What are monoclonal antibodies and what are they used for

A

Antibodies that are identical and will bind to exactly the same feature of the antigen
Used to allow a specific antigen to be targeted
Can be used in the treatment of diseases

49
Q

2 types of cell that are fused when producing monoclonal antibodies

A

B lymphocytes

Myeloma (cancer) cells

50
Q

Why are B lymphocytes used to produce monoclonal antibodies?

A

They allow a specific antigen to be targeted

51
Q

Why are myeloma cells used to produce monoclonal antibodies?

A

B lymphocytes do not divide in culture so myeloma cells allow duplicate cells to be produced

52
Q

What is the name of the cell that results from the fusion of B lymphocytes and myeloma cell?

A

Hybridomas

53
Q

Name the technique used for the fusion of B lymphocytes and myeloma cells?

A

PEG (polyethylene glycol)

54
Q

What are the 2 types of microscope?

A

Bright field

Fluorescence

55
Q

What are bright field microscopes used for?

A

To examine whole organisms,parts of organisms or thin sections of tissue

56
Q

What are fluorescence microscopes used for?

A

To detect specific proteins that have been bound to fluorescently labelled antibodies

57
Q

Define aseptic technique

A

Procedure carried out to ensure sterile conditions

58
Q

State and justify the use of the stages of aseptic technique

A

Sterilisation of containers, equipment and materials - kills off bacteria/contaminants to avoid cross contamination in the experiment
Disinfection of working area - gets rid of bacteria on surface to prevent contamination interfering with experiment
Wire loop flames before use - gets rid of previous contaminants on the wire loop, keeping it sterile
McCartney bottle lid flamed - sterilises the bottle and remove contaminants
Inoculating loop flames after use - ensures the sample does not infer the future cultures/experiments
Petri dish lid only partly opened - makes sure no outside contaminants interfere
Culture dish sealed - ensure that the materials inside the dish stay in the dish/don’t fall out

59
Q

Define the term inoculum

A

Original stock of cells

60
Q

What are explants and how are they created?

A

Small cuttings of whole tissue

61
Q

What is the name of the price of equipment that can be used to calculate cell counts?

A

A haemocvtometer

62
Q

What is the purpose of staining when making cells counts?

A

So you can see the cells

63
Q

What is vital staining and how does it work?

A

A method of staining where only the dead cells change colour. Allows you to distinguish between dead and living cells. Both types of cells would take up the dye but the living cells would pump it back out preventing them from changing colour

64
Q

Define viable cell count

A

Total number of living cells in the sample

65
Q

Define non-viable cell counts

A

Total number of dead cells in the sample

66
Q

Define total cell count

A

The total number of living and dead cells in the sample

67
Q

How would you perform a cell count using a haemocytometer?

A

Work out volume under grid
Divide 1 by volume to find the number of times the volume goes into 1cm3
Count the cells under the grid
Multiply number of cells by the times the volume goes into 1cm3 to find the cells concentration

68
Q

What are the contents and purpose of a simple culture medium?

A

Allows conditions for gas exchange, has a suitable pH and temperature and has a suitable growing surface
Purpose is to provide the basic requirements for cell growth

69
Q

What are the contents of a complex culture medium?

A

Contains different nutrients depending on what you are growing
Examples
Growth factors - stimulate proliferation of cells
Serum - source of growth factors
Food source eg glucose - provides energy for proliferation
pH buffer - prevents change in pH
Auxins - plant growth regulator

70
Q

Why is serum added to media when culturing animal cells?

A

It is a source of growth factors meaning it stimulates proliferation of cells

71
Q

What is a monolayer? (when culturing mammalian cells)

A

Single cell thick confluent layer of cells

72
Q

Compare the lifetime of primary and cancer cell lines

A

Primary cells have a shorter lifetime than cancer cells and cancer cells divide infinitely as they don’t have normal controls

73
Q

What is added to media when culturing plant cells? Why is this required?

A

Auxins because they regulate plant growth

This allows plants to grow in the most energy absorbing way

Advanced Higher Biology (13 decks)

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