Biochem Lab- Midterm

what is the technique of biochemistry based on

measuring how much light at a specific wavelength is absorbed by the substance

what are the two important principles in spectrophotometry

Lamberts Law and Beers law

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

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

what is the standardized pathway length

1 cm

how are absorbance and transmittance related

inversly related

Regression

the statistacal relationship between two variables

linear regression

linear approach between a dependent and independent variable

coefficient of determination

r^2

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

what are the classes of lipids

-phospholipids

-triglycerides

-sterols

phospholipids

diglycerid + phosphate group

triglycerides

oils and fatty acids

sterols

steriods

how does the energy content of lipids compare to carbohydrates

2x the energy for the same amount

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.

why do mammals have high amounts of saturated fats

a high body temperature keeps saturated fats liquid allowing for more energy efficiency

what are most biological lipids

unsaturated, solid saturated fats would cause things to crack

protein concentrations are determined by

colorimetric or the development of color (spectrophotometric)

gravimetric

extraction based on weight/gravity

what does the addition of a salt do to a biphasic sample

it increases polarity, further seperating the polar and nonpolar layers

polar lipids

hydrophilic

nonpolar lipids

hydrophobic

why is glass used over plastic in labs

hydrophobic properties compared to the hydrophilic properties of plastic

Polypropolene (PP)

cloudy plastic, inert and safe to use with wide variety of compounds (organic)

Polystyrene (PS)

clear plastics not safe to use with organic compounds

most abundant organic molecule on earth

cellulose

what is the structrual polysaccharide in plant cells

cellulose

what emzyme do animals produce to break glucose bonds

amylase

what enzyme is used to break cellulose bonds

cellobiase

what group of enzymes is cellobiase a part of, and why is this group heavily studied

cellulases, being studied for use in biofuel industry

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

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

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

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

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

bromelain proteases

digest proteins

TrisEDTA

buffer, pH 8

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

how does EDTA work

chelates calcium, attatches to Ca+ ions and prevents nucleus from working because metal ions are critical in their functions

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

most abundant organic biomass

cellulose

cellulayze

enzyme that digests cellulose

how does glycogen differ from starch

more branched

how is enzyme activity measured

units

enzyme activity is characteristic of

a purified enzyme

disacharide

2 glucose

a majority of enzymes are

proteins

functional property of enzymes

effectiness or product produced/time

cellubios

2 sugars