1.1 Flashcards
What is a risk?
The likelihood that a hazard would cause significant harm
What is a hazard?
The source of potential harm
What is a risk assessment?
Identifying and determining likelihood if harm and implementing measures where necessary
Whats a beaker used for?
General purposes e.g. heating a solvent while the solute dissolves
(50-2000cm3)
How accurate is a beaker?
Not accurate
What is a standard flask?
Flask with a line on the neck to show a very precise volume
(25-1000cm3)
How accurate is a standard flask?
High accuracy
How accurate is a measuring cylinder?
Mid accuracy
How accurate is a pasteur pipette?
Low accuracy
How accurate is an auto-pipette?
High accuracy
How accurate is a syringe?
High accuracy
When is linear dilution used?
Used if you need a sample over a reasonably small range.
For example, 0.1ml, 0.2ml, 0.3ml and so on
What is linear dilution?
When different volumes of concentrated stock solution are added to different volumes of solvent.
What is a benefit of linear dilution?
Each concentration is made individually meaning any errors affect only one concentration
What calculation is used to calculate the concentration in a linear dilution?
C1V1=C2V2
When is log (aka serial) dilution used?
Used when a wide range of concentrations is needed.
Differ by a constant proportion, e.g. 10-1, 10-2, 10-3 and so on
What is log (aka serial) dilution?
Each dilution acts as the stock for the next.
What is a disadvantage of log dilution?
Because each concentration depends on the previous one, any errors are compounded in later dilutions
What is a standard curve?
Is a line or curve produced by plotting measured values for known concentrations.
What can a standard graph be used to estimate?
Unknown concentrations
What is a buffer solution?
A solution whos pH changes very little when small volumes of acid or base is added to it this allows the pH of a reaction mixture to be kept constant
What is the definition of colorimetry?
The use of a colorimeter to quantify concentration of a coloured solution or its turbidity
What is the turbidity of a solution?
Its cloudiness
What is absorbance in a colorimeter?
Used to determine concentrations of coloured solutions
What is the percentage transmission in a colorimeter?
Used to determine turbidity (e.g. cells in a solution)
How is a colorimeter used?
It must be calibrated with an appropriate blank as a baseline
Name 4 separation techniques
Centrifugation
Paper and thin layer chromatography
Affinity chromatography
Gel electrophoresis
What is centrifugation?
Separates substances according to their density.
How does centrifugation work?
A centrifuge spins samples at high speeds (120,000 rpm) causing the densest material to form a pellet at the bottom of the tube whilst the less dense materials remain in the liquid above the pellets - called supernatant
What is paper and thin layer chromatography?
Used to separate different substances such as amino acids and sugars
How does paper chromatography work?
A sample is placed in a dot near the bottom of the strip of chromatography paper which is placed in solvent. Solvent travels up the paper carrying components of the mixture
How does Thin Layer chromatography work?
Same as with paper chromatography except its performed on a sheet of glass or plastic which is coated with a thin layer of absorbent material
Give examples of materials TLC glass/plastic is coated with?
Silica gel or cellulose
What is affinity chromatography?
Used to separate target proteins
How does affinity chromatography work?
A solid matrix/ gel column is created with specific molecules bound to its surface. Sample mixture containing soluble target proteins with high affinity is poured over matrix target proteins bind and waste runs through and is discarded. Entrapped substances is removed/eluted in pure form why washing through a solution with high affinity for target protein.
What is gel electrophoresis?
Used to separate proteins, protein fragments and nucleic acids based on their charge, shape or size.
What are the two types of gel electrophoresis?
Native gel
Sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE)
Whats native gel electrophoresis?
When proteins move depending on mass and structure
What is SDS-PAGE electrophoresis?
Proteins move depending on mass only
What is the isoelectric point of a protein?
A pH at which a soluble protein has no net charge and precipitates put of solution. (For example in gel electrophoresis)
What are immunoassay techniques used for?
To detect and identify specific protiens. They can use antigens to detect antibodies or vice versa.
What are antibodies?
Y-shaped proteins
What makes antibodies?
B lymphocytes
How many antibodies will lymphocytes make in response to an antigen?
One specific antibody specific to one type of antigen.
What are two sites of B lymphocyte production?
Spleen
Bone marrow
What is ELISA?
Analytical technique
Uses stock antibodies with the same specificity (monoclonal antibodies) to detect antigens in solution
What are the three forms of ELISA?
Direct
Indirect
Sandwich
What is direct ELISA?
Antigen binds to the surface of a multiwall plate. A primary antibody, linked to a chemical label is then added. The ‘label’ is often a reporter enzyme producing a colour change, but chemiluminescence (aka chemoluminescence), fluorescence and other reporters can be used
What is Indirect ELISA?
Same as direct except after the primary antibody is added to the well and binds to the antigen.
Then a second antibody that is linked to a reporter enzyme is the added, which binds to the primary antibody.
What is sandwich ELISA?
Same as direct and indirect except a capture antibody is bound to the multiwall plate not an antigen.
Then primary and secondary antibody is the same as in indirect.
What is western blotting?
Lab method used to detect specific protein molecules from amongst a mixture of proteins.
How does western blotting work?
Following SDS-PAGE separated proteins from the gel are blotted onto a solid medium. Proteins can be identified using specific antibodies that have reporter enzymes attached (ELISA)
What are the two types of microscopes?
Bright field
Fluorescent
What is bright field microscopy?
When a sample is mounted onto a slide and illuminated from below. Samples often stained to increase contrast.
When would bright field microscopy be used?
To observe whole organisms, parts of organisms, thin sections of dissected tissue or individual cells.
What is fluorescence microscopy?
Uses specific fluorescent labels to bind to and visualise certain molecules e.g. proteins or structures.
Absorbs a specific wavelength (colour) of light then emits a different wavelength.
When is fluorescent microscopy used?
To
What is the definition of an aseptic technique?
Eliminates unwanted microbial contaminants when culturing microorganisms or cells. This involves the sterilisation of equipment and culture media by heat or chemical means and subsequent exclusion of microbial contaminants.
What is a cell culture?
The ability to grow cells in an artificial laboratory environment (e.g. culturing mammalian cells for cancer studies)
What is a microbial culture?
Method of multiplying microorganisms by letting them reproduce in a culture medium under controlled laboratory conditions
How can a microbial culture be started?
Using an inoculum of microbial cells on an agar medium or in a broth with suitable nutrients
What is the definition of a cell line?
A genetically uniform cell culture developed from a single cell.
What is flow cytometry?
Technique used to detect and measure physical and chemical characteristics of a population of cells or particles.
What are 7 uses of flow cytometry?
Cell counting
Cell sorting
Determining cell characteristics and functions
Detecting microorganisms
Biomater detection
Protein engineering detection
Diagnosis of health disorders such as blood cancers
