Practicals Flashcards
Define electrophoresis
A method of analysing molecules on the basis of charge, by mesuring their migration in an electric field
Define specrophotometry
A way of analysing molecules on the basis of their spectral properties.
Define the absorbance, A, in specrophotometry.
log10(light transmitted through blank solution/light transmitted through test solution)
What is the beer lamberr law?
A = E x c x l
A is absorbance
E is extinction coefficient
c is concentration of absorbing substance
l is the path length
What is the absorbance of a solution proportional to?
The concentration of the absorbing material within it and the distance travelled by the light through the sample.
How can lymphocytes be identified with a microscope?
They are small cells with a spherical nucleus and little cytoplasm.
How can eosinophils be identified with a microscope?
Their cytoplasmic granules are bright pink, with a bi-lobed nucleus.
How may neutrophils be identified on a microscope?
They have a multilobed nucleus (polymorphonuclear) with cytoplasmic granules.
How can basophils be identified with a microscope?
Their cytoplasmic granules stain strongly blue. They have a lobed nucleus.
How can monocytes be identified with a microscope?
They have an indented nucleus with pale granules in the cytoplasm.
What is Vmax?
The maximum enzyme velocity which is allroached as substrate concentration increses.
What is Km?
Michaelis constant - the substrate concentration at which the rate of reaction is exactly half Vmax.
What is on the axes of a lineweaver-burk plot?
The x axis has 1/substrate concentration, and the y reaction 1/velocity (Vo).
What is the x intercept of a lineweaver-burk plot?
-1/Km
What is the y intercept of a lineweaver-burk plot?
1/Vmax
How do competitive inhibitors affect Km and Vmax?
Km increases and Vmax is the same.
How so non-competitive inhibitors affect Km and Vmax?
Vmax decreases and Vm stays the same.
What does vinblastine, a cancer drug, inhibit?
It binds to tubulin and therefore inhibits assemble of microtubules, targetting metaphase
What is tay-sachs?
The absense of the enzyme hexosaminase-A. This causes accumulation of a lipid in cells. Brain cells are destroyed.
Define penetrance.
The number of people in a population with the disease.
Define consanguinity.
Having a relationship with someone you share a relative with.
How do you represent an unknown sex on a genetic pedigree?
A diamond shape.
How can you distinguish between gram positive and gram negative bacteria?
Gram positive bacteria stain purple, and gram negative bacteria stain red.
What stains are used in gram stain technique?
- Add crystal violet
- Wash with water
- Add lugols iodine
- Rinse then cover with alchohol
- Add safranin and then rinse
When is the catalase test used and what are the results?
- Used on gram positive cocci
- Positive is clusters, negative is chains
What are the results when bacteria are grown on agar to test if they are lactose fermenters?
- The plate is red/pink if the bacteria are lactose fermenters
- The plate if colourless/yellow then the bacteria are lactose non-fermenters
What are alpha, beta and gamma types of haemolysis?
- Alpha is a small zone of haemolysis, and colonies appear green
- Beta is a large clear zone of haemolysis
- Gamma is no haemolysis
When is the oxidase test used?
To determine if an organism produces cytochrome c oxidase
When is MacConkey Agar used?
To determine the lactose fermentation by bacteria.
