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Advanced Higher Biology > 1.1 - Cells And Proteins > Flashcards

1.1 - Cells And Proteins Flashcards

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1
Q

What are buffers?

A

Buffers are solutions that resist PH changes

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2
Q

Why are buffers used in experiments?

A

They are used to maintain pH level in experiments in which pH is a possible confounding variable

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3
Q

The solubility and affinity of an amino acid is dependent on what?

A

It’s r group

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4
Q

What is centrifugation used to?

A

Separate components of a suspension that have a different density.

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5
Q

How do you separate components of a suspension that have a different density?

A

Centrifugation

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6
Q

What does homogenisation mean?

A

Using a motar and pestle, sieve or liquidiser to break open all cells.

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7
Q

Describe the process of centrifugation

A

A suspension is placed in a centrifuge tube.
The tube is then supn in a centrifuge machine.
After a time,
The denser components are separated into a pellet.
While less dense components remain suspended in the supernatant.

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8
Q

What are toxic chemicals?

A

Substances that are harmful when inhaled, ingested, injected or absorbed.

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9
Q

What are corrosive chemicals?

A

A reactive substance that can damage living tissue

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10
Q

What is a reactive substance that can damage living tissue?

A

A corrosive chemical

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11
Q

How do corrosive chemicals act?

A

Either by chemically destroying part of the body or indirectly by causing inflammation

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12
Q

What corrosive substances are commonly found in biology labs?

A

Acids and bases

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13
Q

why should lab workers be aware of sources of heat?

A

To prevent burns and scalds

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14
Q

What sources of heat should lab workers be aware of?

A

Lighted Bunsen burners
Electric ovens
Hot plates
Steam baths

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15
Q

What are pathogenic organisms?

A

Organisms that can cause disease

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16
Q

Are pathogenic organisms a biohazard?

A

Yes

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17
Q

What pieces of mechanical equipment are hazards that lab workers should be aware of?

A 
Machines that have;
Moving parts
Vibrating parts
Hot surfaces 
Sharp components 
Heavy components
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18
Q

What are the main physical risks from mechanical equipment?

A

Noise
Hand/arm/whole body vibration
Heat stress

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19
Q

What are the main mechanical risks from mechanical equipment?

A

Cuts
Lacerations
Needle punctures
Crushing

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20
Q

What is risk?

A

Risk is the likelihood of harm arising from exposure to a hazard

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21
Q

What does a risk assessment involve?

A

Identifying risk levels
Their likely severity
And the control measures that can be used to minimise risks.

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22
Q

Some control measures include

A

Using appropriate handling and disposal techniques
Using appropriate masses,volumes and concentrations of substances
Use of protective clothing such as lab coats and gloves
Use of protective equipment such as googles and masks
Use of aseptic technique in microbiology

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23
Q

What are liquid volumes expressed in?

A

Ml or CM3

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24
Q

When are linear dilutions used?

A

When the substance being diluted is the idependent variable in an experiment

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25
How do liner dilutions differ from each other?
By an equal interval
26
How do you make a linear dilution of a substance?
Start with a stock solution with a known concentration Add increasing, stepped volumes of the stock solution to separate tubes Then add pure distilled water to each tube to make the volume up to the same for each tube
27
When are log dilutions often used?
In microbiology, | To estimate the concentration or density of cells in a stock culture.
28
How do log dilutions differ?
Dilutions in a log dilution differ, by a constant proportion eg. 10-1, 10-2, 10-3
29
How are log dilutions created?
By diluting a stock solution by a factor and then further diluting the dilution produced by the same factor and so on.
30
How can log dilutions be used to estimate the concentration or density of cells in a stock culture?
The serial dilution produces low concentrations of cells that can be cultured on an agar plate. Producing a number of easily countable colonies. From this result , the estimated number of cells in the original stock can be calculated.
31
What can colorimeters be used to determine?
The concentration of solutions that have been coloured by an indicator Or The turbidity of a cell culture
32
How does a colorimeter determine the concentration of solutions that have been coloured by an indicator?
Light is passed though a sample of the solution The sample is contained in a small tube called a curvette An electronic sensor detects how much light has been absorbed as it is passed through the solution or culture suspension.
33
What us Turbidity proportional to?
The density of cells in the culture
34
What is the density of cells in the culture proportional to?
The turbidity
35
How is the turbidity of a cell culture determined with a colourimeter?
Light is passed through a sample of the culture in a cuvette | An electronic sensor detects how much light has been transferred through the culture suspension
36
What must be done before measuring concentration or turbidity with a colorimeter?
The instrument must be calibrated using a blank as a baseline
37
What is a blank?
A curvette containing only the solvent used when making dilutions or a sample of the mediums used in the cell culture.
38
Most ——————— reactions are dependent on PH
Biological
39
Why are buffer solutions used in in-vitro experiments?
So that changes in PH during the reaction dont act as confounding variables and cause a mistaken association between independent and dependent variables
40
A linear dilution of a substance , such as glucose, can be used to produce a ——————- curve
A standard curve
41
What does homogenisation mean?
Splitting open of cells
42
What are some homogenation methods?
Pestle and mortar Sieve Liquidiser
43
What does homogenisation mean?
Splitting open of cells
44
What is centrifugation used to separate?
Components of a suspension that have a different density
45
How does centrifugiation work?
The cell homgenate is placed in a centrifuge tube Which us then spun a centrifuge machine at between 200 and 120,000 revolutions per minute After a time the denser components of the cells are separated into a pellet While less dense components remain suspended in the supernatant
46
What is chromatography used to?
Separate different solutes such as amino acids and sugars
47
How does paper and thin layer chromatography work?
Mixtures of these substances dissolved in a solvent cab be added to a paper strip or to a metal foil strip with a thin layer of silica or cellulose bonded to it. The speed that each solute travels along the strop depends on its differing solubility in the chromatography solvent used, and its differing affinity for the paper or thin layer. If the substances being separated are colourless, Luke amino acids, they must be made visible on the paper or thin layer using a developing agent. The solubility and affinity of an amino acid is dependent on its R group.
48
What is affinity?
The degree to which a substance is attracted to and tends to bind to another.
49
What is affinity chromatography?
A technique used to separate and purify proteins based on a specific binding interaction between an immobilised ligand and its binding partner.
50
What is an antigen?
A specific protein with which antibodies can bind an immune response.
51
What is aseptic technique?
Procedures in place to prevent contamination, including sterilising equipment and work surfaces.
52
What is bright-field microscopy?
Microscopy commonly used to observe whole organisms , parts of organisms, thin sections of dissected tissue or individual cells.
53
What is a buffer?
A solution used to set and maintain a particular pH
54
What is centrifugation?
A process that used centrifugal forces to separate components of different densities in a mixture.
55
List 5 hazards found in biology laboratories
``` Toxic chemicals Corrosive chemicals Flammable chemicals Pathogens Mechanical hazards ```
56
Describe what is meant by a risk assessment
Identifying risks | Identifying control measures
57
Describe how you would make a linear dilution series of a 1M glucose solution
Mix 9ml of stock with 1 ml solvent to give 0.9M 8ml stock with 2ml solvent to give 0.8M And so on
58
Describe how you would make estimate the bacterial cell density in a sample of Escherichia Coli in a culture of stock solution
Carry out serial log dilutions to give 10-5/very dilute suspension Plate out dilute suspension and incubate Count colonies Calculate original cell density
59
Describe how you could use colourimetry and a standard curve to identify the glucose concentration of an unknown solution
Make up glucose solutions of known concentration Put each through colorimeter to determine absorbance Draw standard curve Put unknown through colorimeter And determine absorbance Read concentration from standard curve
60
Explain what buffers are and why they are used in experiments
Solutions that resist pH changes | Used to maintain pH level in experiments in which pH is a possible confounding variable
61
Explain how centrifugation achieves separation of a suspension into a pellet and a supernatant
Centrifugation separates by density The most dense material is in the pellet The least is left in the supernatant
62
Describe how a solution with three different amino acids can be separated
Add spot of solution to origin line of paper/thin layer chromatography strip Dip in (appropriate) solvent and allow it to run in Develop with amino acid stain
63
Describe how proteins in a mixture can be separated by affinity chromatography
Add mixture to column Target protein binds to ligand/antibody in column Other proteins run through Target protein then collected by washing out column
64
Explain the difference between native and SDS-PAGE techniques
In native PAGE, proteins are separated in electric field on the basis of mass and charge In SDS-PAGE proteins are denatured/all given negative change and separated in electric field on the basis of mass
65
Explain how iso electric point can be used to separate proteins
At its iso electric point, a protein has not net charge, it precipitates If a mixture is run through a pH gradient gel each protein precipitates at its iso electric point.
66
Explain what is meant by a monoclonal antibody
Supply of antibodies all with the same specificity/which bind to the same antigen
67
Describe how a reporter enzyme works
Bound to an antibody that binds to an antigen in immunoassay well Substrate added, which is converted to coloured protein
68
Describe western blotting
Proteins separated by gel electrophoresis Separated protein blotted onto membrane Treated with reporter
69
Explain why aseptic technique is used when working with cell cultures
To prevent contamination | Prevent competition with target microbe

Advanced Higher Biology (8 decks)

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