lab exam Flashcards
(64 cards)
what were the four reagents used for the tonicity lab
NaCl 0.15 and 0.8, ethlyene glycol 0.3, and distilled water
which reagents lysed the rbc
the ethylene glycol and distilled water
which solutions were isotonic
The NaCl since there was no net movement
which solutions were hypotonic to the RBC
the ethlyene glycol and the distilled water since they both lysed the rbc
which solutions were hypertonic to the RBC
NaCl 0.8, because there was a conc gradient but the NaCl was not permeable so the water had to leave the cell
how come NaCl 0.15M did not lyse the cell but ethlyene glycol did
because from the lab it can be deducted that the cell membrane is not permeable to NaCl, so no matter the concentration it will not be able to enter the cell, however ethlene glycol is so it can enter the cell
how were the RBC’s in the NaCl behaving?
when we are changing the temperature why is a negative control important
this helps us differentiate whether the cell lysed because of the permeability due to the temperature change or if it lysed due to the denaturing of the cell at high temperatures, so in part b if the control lysed this indicated that the results are not valid because the control should not lyse
what are the independent and dependant variables when changing temp to see effects on the cell permeability?
the independent variable is temp because we control it, and the dependant is the cell permeability because it depends on the temperature
what is a good negative control solute
NaCl, because we know that it should not lyse since it is not permeable so it should not be able to enter the cell even if the temp is increased unless the cell is denatured
what is a good solute for the treatment
ethylene glycol, because this allows us to gain an insight on the cell permeability, wheres in water it lyses at a really fast rate and through osmosis so we do not learn much about the effect of temp on cell permeability
what is the partion coefficient
it is the ratio of the solute to the water so the higher it is the higher the membrane permeability is increased
what are the different pipette sizes
p20: 2-20 ul
P200: 20-200 ul
P1000: 100-1000ul
what are two benefits of loading dyes
they make the DNA visible, making it easier to track in the gel, they also weigh the sample down so it does not float away
what does a serological pipette do
it used to pipette exact amounts, 1ml, 2ml, 5ml, 10ml, and 25ml
what does a pasteur pipette do
it is used to pipette large amounts where preciseness is not important
which part of the DNA is negatively charged
the phosphate group
how does a gel work
there is a negative and positive side, the DNA is repelled my the negative side and is attracted to the positive side, the smaller the DNA fragment the faster it moves and closer it gets to the positive side
what bond connects the two nucleotides
phosphdiester bond
what do you find at the 5-3 end and the 3-5 end
OH (hydroxyl) and OPO3 (phosphate)
where are h bonds found
in between the nitrogenous bases
what is the difference between major and minor grooves
major grooves are when the back bones are far apart
minor grooves are when they are close together
how can you distinguish adenine and guanine
guanine has a double bonded oxygen, also has a triple hydrogen bond, adenine has a NH2 group, also has a double hydrogen bond
what is the purpose of the DNA ladder
it is used as a reference to compare the other DNA samples by comparing the migration of the samples to the ladder, it can also be used to verify whether the DNA gel is working effectively