AAMC C/P Section Bank-done Flashcards
Thin lens formula
1/o + 1/i = 1/f
o=object
i=image
f=focal length
kinetic energy in the photoelectric effect
hf-W
Which alcohol will most likely undergo substitution by an SN1 mechanism in acidic conditions?
Tertiary
this alcohol produces the most stable carbocation (tertiary) and consequently will most easily lose a water molecule upon protonation of the hydroxyl group in acidic media
Energy is
power/time
fingerprinting as proteolytic cleavage is a ____ reaction
hydrolysis
Ohm’s Law
R=V/I
Thermodynamic vs kinetic control
Thermodynamic products are favored at high temperatures, have lower energy, and are more stable. However, their formation occurs more slowly because greater activation energy is required. Kinetic products, on the other hand, are favored at a lower temperature, have higher energy, and are less stable.
So based on this, I reasoned that because compound 2 formed new liposomes with a size that was EXPECTED it is thermodynamic/favorable and compound 1 did not change with the conditions so it was the less favorable & kinetic.
free energy of the reaction ΔG′°
ΔG′° = –RTln(Keq)
The free energy of the reaction ΔG′° is related to the equilibrium constant Keq = [ADP][Pi]/[ATP] as ΔG′° = –RTln(Keq). Applying [Pi] = 1 and using the expression for Keq gives ΔG′° = –RTln([ADP]/[ATP]), so that [ADP]/[ATP] = e(30/2.5) = e12.
What is the electronic configuration of the Co(II) center found in vitamin B12?
[Ar] 3d7
Co(II) is a dication and is formed from the atomic element by the loss of two 4s electrons. As a consequence, only seven 3d electrons remain in the valence shell.
The ATP-dependent phosphorylation of a protein target is catalyzed by which class of enzyme?
Transferase
The answer is B because kinases catalyze the transfer phosphate groups from ATP to target proteins and are classified as transferases. The item stem describes a kinase.
What was the most likely purpose of adding bovine serum albumin to the kinetics experiments in the passage? Bovine serum albumin:
prevents the esterase from adhering to the walls of the vessel
The answer to this question is B since the passage specifically states that albumin is a protein that mobilizes proteins and lipids in serum. In the context of a kinetics experiment it is perfectly logical to assume that albumin is added to maintain homogeneity and prevent the enzyme from adhering to walls and other surfaces which would inhibit its activity.
catalytic efficiency
kcat/km
bond that links monosaccharides together in an oligosaccharide is a special type of acetal linkage known as a _____ bond
glycoside
anion-exchange column
In an anion exchange column, the packing is positively charged and therefore retains negatively charged molecules by coulombic interaction.
By increasing the salt concentration (generally by using a linear salt gradient) the molecules with the weakest ionic interactions start to elute from the column first.
If there is a single band at 35 kDa on a reducing SDS-PAGE, what size the the tetramer?
140 kDa
In an SDS-PAGE under non-reducing conditions, disulfide-linked groups will not be _____.
reduced
In an SDS-PAGE under non-reducing conditions, monomers, homotrimers, etc, will run as ____.
monomers
A protein contains four disulfide bonds. In order to break these bonds researchers added a minimum of:
4 moles of NADH for each mole of protein
The answer is B because each mole of NADH can reduce a mole of disulfide bonds. Since the protein has four disulfide bonds, four moles of NADH are needed.
A protein with which properties will most likely have the largest negative net charge at pH 7?
a protein that binds to an anion-exchange column at ph 7 and required high NaCl concentration for elution
On a thermal denaturation graph, where is the melting point
Tm is the temperature at which 50% of the molecules are denatured or the fraction folded is 0.5.
Galactose
6 C ring aldose
Hydrogen bond donors and acceptors of all DNA bases (know the structures too)
hydrogen bond acceptors are N and O. Adenine contains 1 donor and 1 acceptor, thymine contains 1 donor and 1 acceptor, guanine contains 2 donors and 1 acceptor, and cytosine contains 1 donor and 2 acceptors.
Thermal denaturation experiments can be used to follow the transition of double-stranded DNA into single-stranded DNA. Which of the following parameters affects the Tm of dsDNA in this experiment?
pH of solution
Ionic strength of solution
Length of DNA strands
All
The answer is D because all of these parameters would affect the thermodynamic stability of the DNA double helix. Significant drops in pH would result in protonation of hydrogen-bond acceptors, leading to a loss in base-pairing interactions. The presence of positive ions in solution (particularly Mg2+) leads to stabilization of the DNA fold via shielding of the repulsion between phosphate groups within the DNA backbone. The length of DNA strands would also play a role. Longer DNA strands are held together by more hydrogen bonds, meaning that more energy is required to denature the double-stranded DNA.
Which is heavier: guanosine or deoxyguaosine
deoxy
Adenosine = adenine + ribose sugar
deoxyadenosine = adenine + deoxyribose sugar (has one less OH group, and has H instead)
