Lab techniques Flashcards
What is a risk?
Risk is the likelihood of harm arising from exposure to a hazard.
What does a risk assessment involved?
A risk assessment involves identifying control measures to minimise the risk.
What does COSHH stand for? And what are COSHH regulations
Control of substances hazardous to health
Regulations cover substances that are hazardous to health
What are examples of substances covered by COSHH regulations
chemicals;
products containing chemicals;
fumes;
dusts;
vapours and mists;
nanotechnology;
gases and asphyxiating gases;
biological agents.
What is considered in the COSHH assessment form?
exposure, disposal procedures and handling procedures
Why do scientist wear personal protective equipment (PPE)
reduces the risk of hazardous materials coming into contact with the skin where it could cause harm
What is a dilution?
Dilution involves reducing the concentration of a substance in a solution
What is serial dilution?
Repeated dilution from a stock solution
What are dilutions in a linear dilution series?
differ by an equal interval
What are dilutions in a log dilution series?
differ by a constant proportion
What can you use serial dilutions for?
An investigator may need to know the number of bacterial cells which are contained within an environmental sample. It is likely that there are too many cells in the sample to physically count every one; therefore, we can carry out a dilution series
What do you use a colorimeter for?
The concentration of a pigmented compound can be quantified using a colorimeter
What does a colorimeter measure?
A colorimeter measures the absorbance of specific wavelengths of light by a solution.
How does a colorimeter work?
A colorimeter works by passing a light beam, at a specific wavelength, through a cuvette containing a sample solution. Some of the light is absorbed by the sample; therefore, light of a lower intensity hits the detector and the machine will display an absorbance or transmission value.
How to calibrate a colorimeter?
To calibrate a colorimeter, a cuvette containing calibration solution (usually distilled water) is placed in the cuvette compartment and the calibrate button is pressed
What types of readings do colorimeters produce?
absorbance - how much light has been absorbed by the sample;
transmission - how much light passed through the sample without being absorbed.
What can absorbance determine?
Absorbance can be used to determine concentration of a coloured solution using suitable wavelength filters.
What can percentage transmission be used to determine?
Percentage transmission can be used to determine turbidity, such as cells in suspension (as the concentration of cells increases, the turbidity of the culture increases)
What can a standard curve be used to calibrate?
determine the concentration of a solution
What is a centrifuge used for?
To separate substances according to their density. The densest materials separate out first and form a pellet at the bottom of the tube. The liquid which remains above the pellet is called the supernatant.
Paper and thin layer chromatography can be used for separating different substances such as?
amino acids and sugars
The process of affinity chromatography?
- relies on the binding interactions between a protein and specific molecules bound to a matrix or gel
- A specific molecule is immobilised on an inert support in a column and a protein mixture is passed through the column
- The target protein, which is complementary to the specific molecule in the column, will bind to it and remain in the column when the other components are washed away
gel electrophoresis can separate what?
proteins and nucleic acid
Native gels used in gel electrophoresis separate proteins by what?
shape, size or charge
What is SDS-PAGE?
A form of gel electrophoresis. Proteins are denatured and given a uniform negative charge; this means that the proteins can be separated based on their size as they migrate towards the positive electrode. Small proteins travel further through the gel than large proteins.
Proteins can be separated from a mixture using what?
Their Iso-electric point (IEP)
If the solution is buffered to a specific pH what will happen?
only the protein(s) that have an IEP of that pH will precipitate
Immunoassay techniques are used to detect and identify what?
specific proteins
What are monoclonal antibodies?
an antibody that binds to a single epitope/part of antigen
Western blotting is a technique, used after what?
SDS-PAGE electrophoresis as the separated proteins from the gel are transferred (blotted) onto a solid medium
Any antibody used in an immunoassay must be linked to what?
A detectable label to allow scientists to detect when binding has occurred. These labels may be in the form of a reporter enzyme which causes a colour change in the presence of a specific antigen.
Bright-field microscopy is commonly used to observe?
whole organisms, parts of organisms,
thin sections of dissected tissue or individual cells
Fluorescence microscopy uses what?
specific fluorescent labels to bind to and visualise certain
molecules or structures within cells or tissues
What is the function of aseptic technique?
eliminates unwanted microbial contaminants when culturing
micro-organisms or cells
A microbial culture can be started using?
an inoculum of microbial cells on an agar medium,
or in a broth with suitable nutrients
function of serum?
contains growth factors
primary cell lines can?
divide a limited number of times
tumour cells lines can?
perform unlimited divisions
Plating out of a liquid microbial culture on solid media allows?
the number of colony-forming
units to be counted and the density of cells in the culture estimated
Vital staining stains what?
viable cells
