measuring how much light at a specific wavelength is absorbed by the substance
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what are the two important principles in spectrophotometry
Lamberts Law and Beers law
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lamberts law
the proportion of light absorbed by a medium is independent of the intensity of incident light , this allows different spectrophotometers to produce comparable absorption readings
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Beers law
the absorbance of light is directly proportional to both the concentration of the substance absorbing light and the thickness (pathway) of the medium
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what is the standardized pathway length
1 cm
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how are absorbance and transmittance related
inversly related
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Regression
the statistacal relationship between two variables
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linear regression
linear approach between a dependent and independent variable
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coefficient of determination
r^2
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why is r^2 useful
it describes how reliable the equation is in describing the relationship between x and y and is always presented with a regression equation. Ranges 0-1, the closer to 1 the more reliable the regression equation is
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what are the classes of lipids
\-phospholipids
\-triglycerides
\-sterols
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phospholipids
diglycerid + phosphate group
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triglycerides
oils and fatty acids
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sterols
steriods
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how does the energy content of lipids compare to carbohydrates
2x the energy for the same amount
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how do saturated and unsaturated fatty acids compare in energy contents
saturated fatty acids have a higher ebergy content than unsaturated fatty acids due to thier ability to stack evenly and form interactions across chains.
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why do mammals have high amounts of saturated fats
a high body temperature keeps saturated fats liquid allowing for more energy efficiency
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what are most biological lipids
unsaturated, solid saturated fats would cause things to crack
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protein concentrations are determined by
colorimetric or the development of color (spectrophotometric)
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gravimetric
extraction based on weight/gravity
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what does the addition of a salt do to a biphasic sample
it increases polarity, further seperating the polar and nonpolar layers
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polar lipids
hydrophilic
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nonpolar lipids
hydrophobic
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why is glass used over plastic in labs
hydrophobic properties compared to the hydrophilic properties of plastic
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Polypropolene (PP)
cloudy plastic, inert and safe to use with wide variety of compounds (organic)
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Polystyrene (PS)
clear plastics not safe to use with organic compounds
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most abundant organic molecule on earth
cellulose
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what is the structrual polysaccharide in plant cells
cellulose
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what emzyme do animals produce to break glucose bonds
amylase
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what enzyme is used to break cellulose bonds
cellobiase
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what group of enzymes is cellobiase a part of, and why is this group heavily studied
cellulases, being studied for use in biofuel industry
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why is the artificial substrate p-nitrophenyl glucopyranoside used in place of glucose
it becomes yellow in stop solution allowing for readings from the spectrophotometer
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how does heat effect rate of reactions
heat will speed up the movement of substrate and enzyme molecules leading to more collisons, after a certain point enzymes will begin to denature because of the temperature
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how does pH effect rate of reaction
substrate and enzymes interact through positive and negitve charged sides, changes in pH can lead to the enzyme and substrate loosing thier positive and negative charges
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how does enzyme concentration effect the rate of the reactions
increasing the enzyme concentrations would allow the reaction to occur quicker but it is limited by the amount of substrates present
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how doe sthe substrate concentration effect rate of reaction
increasing the concentration would increase the initial rate of the reaction because there would be more substrates open to enzymes in the beginning
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bromelain proteases
digest proteins
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TrisEDTA
buffer, pH 8
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why is TrisEDTA used in DNA isolation
it has a pH of 8 and DNA is stable in alkiline conditions while RNA is stable in acidic conditions
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how does EDTA work
chelates calcium, attatches to Ca+ ions and prevents nucleus from working because metal ions are critical in their functions
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why must there be enough cations in solution when doing DNA isolation
to neutralize the negatively charged phosphates that clump DNA together and allows the DNA to interact with the solvent
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Flashcard (46)