Bio lab final Flashcards
What percentage of bleach to dilute biological spills and for how long?
10% for 2 minutes
What did we use methylene blue for?
Making a standard curve in the first lab
Function of standard curves and how they are made
Standard curves are prepared with known concentration of a substance. The equation of the line can be used to interpolate (determine) the unknown concentration of the same substance.
What do standard curves demonstrate?
The relationship between known concentrations and absorbance
Does the relationship of a standard curve have to be linear?
yes
What is the absorption maximum and when does it have to be determine?
The wavelength at which light is maximally absorbed by a specific molecule is called its absorption maximum
Has to be determined before the curve is made
When making standard curves where do the major and minor lines go
Major outside
Minor inside
Why do we measure wavelength at the absorption maximum?
Ensures highest sensitivity and minimize deviations from Beer’s Law
What are standards?
Known concentration of a substance
When are absorption values proportional to the concentration of a substance?
the absorption maxima is known and used to measure the absorbance
the appropriate control is used as a blank
The relationship is linear
What do we use chromogens when measuring absorbance? And what do they do?
Because cellular components are usually colourless
When they react with a product they turn colour
The absorption can be used to determine concentration of the substance
Is the compound or concentration known in spectrophotometry?
Compound
What is spectrophotometry?
Technique that measures absorbance of energy (light), of a molecule in solution using a spectrophotometer
What is Beer’s law and equation
The absorbance is proportional to the concentration. More concentrated product have higher absorbances
A=kCL
What is the difference vs absorbance and absorption
Absorption is the process of absorbing light
Absorbance is the measure of how much light is absorbed
What is the absorption spectrum?
graph of the amount of light a substance absorbs. The maximum absorption is the peaks
Is the control used as a blank in making a standard curve? And what does it contain?
The control is used as a blank → contains everything except chromagen → use this to set the spectrophotometer to 0
What are two things we need to make sure when making a standard curve?
The concentrations of the standards must be chosen so that they fall within the range of sensitivity of the chromogen being used.
Also,the concentration of the unknown must be within the range of the standard curve.
What physical property do spectrophotometers measure?
Measures the transmittance of light of a specific wavelength through a sample and gives a reading of absorbance
What colour tips to use with a P10, P20, P200, and P100 pipette
P10 -> white
P20 and P200 –> yellow
P1000 –> blue
P1000 pipette volume
800 µL
P1000 pipette volume
600 µL
P200 Pipette volume
40 µL
P200 pipette volume
100 µL