Practice AAMC exam 1 Flashcards
a stereospecific reaction
- a run in which the stereochemistry of the reactant completely determine the stereochemistry of the product
- look if another stereoisomer of the reactant will give identical products in identical ratios- if so the reactant is NOT stereospecific
stereochemistry of SN1 rxn, vs SN2 Ron
SN1=mixture of retention and inversion (2 steps- unimolecular= only depends on [ ] of one - the alkyl) - only depends on the concentration of the alkyl bc it just depends on how many leaving groups leave)
-carbocation forms
SN2- always an inversion
( one simultaneous step- only a transition state (5 bonds- so cannot do on tertiary carbon)- no carbocation)
SN2 will not happen on?
tertiary alkyls- bc a transition state happens, not a carbocation- so the more substituted the less likely
SN1 favours
tertiary alkyls, and more substituted substrates proceed faster!
speed of SN1 vs speed of SN2 on primary? secondary? tertiary?
SN2 -favours primary- fastest
SN1- favours tertiary - fastest ( most stable carbocation)
SN2 stereochemistry vs SN1
SN2 will always be an inversion bc the nuc attacks on the opposite side of leaving group
Sn1- can be inversion or retention, bc leaving group leaves first- carbocation, which can be attacked on either side
stereospecific vs stereoselective reactions!
A stereospecific reaction is a reaction in which the stereochemistry of the reactant completely determines the stereochemistry of the product without any other option.
A stereoselective reaction is a reaction in which there is a choice of pathway, but the product stereoisomer is formed due to its reaction pathway being more favourable than the others available.
The main difference between stereospecific and stereoselective reactions is that a stereospecific reaction gives one specific product whereas stereoselective reaction gives multiple products.
Which of the following statements does NOT correctly describe the dehydration of malic acid to fumaric acid and maleic acid?
a, The reaction occurs most readily with tertiary alcohols.
B. The reaction involves the loss of a water molecule.
C. The reaction has a carbocation intermediate.
D. The reaction is stereospecific.
in passage it says the dehydration results in the formation of fumaric acid, and its cis isomer, malice acid
therefore - it is NOT stereospecific - bc if it was there would be only one specific product
a- this reaction occurs most readily with tertiary alcohols bc when alcohol acts with protic acids to lose a water molecule and form an alkene–> water must leave= carbocation- the more subsituted the most stable
steps in dehydration of alcohol in presence of protic acid
- protonating alcohol
- water leaves
- carbocation formed (+ charge) - rate-limiting step
- alkene formation -
E1 vs E2
how are they related to sn1 and sn2
E1 - secondary and tertiary
- alkyloxoanium forms, leaves, carbocation, then the water molecule (strongish base) grabs another proton from adjacent carbon- double bond forms
- depending on the hydrogen that gets abstracted- will depend on the placement of the double bond - Zaitsev rule states that the major product will be the most substituted product- and trans is better than cis
SN1 and E1 are grouped together because they always occur together. … Both E1 and SN1 start the same, with the dissociation of a leaving group, forming a trigonal planar molecule with a carbocation. This molecule is then either attacked by a nucleophile for SN1 or a base pulls off a b-hydrogen for E1
E2- proton lost from carbon at the same time as water leaves- no in between formation of unstable acarbocation (if it was a primary alcohol)
dehydration of alcohols yeild
alkenes (undergo E1 or E2) - need strong acid to protonate OH- to for (alkyloxanuim ions -H2O still attached) for leaving group
- and need hella heat !
what type of alcohol needs the most heat for dehydration?
primary
Zaitsev’s Rule
the more substituted alkenes are formed preferential because they are more stable than less substituted alkenes
- furthermore, trans alkenes are more stable than cis alkenes are are also the major product
carbocation rearrangments
very common in run when a carbocation moves to a more stable state through “shifts”
- hydride and alkyl shifts
hydride shift
- This means that the two electron hydrogen from the unimolecular substitution moves over to the neighboring carbon.
- this is typical when alcohol reaches with H-halide
- Whenever a nucleophile attacks some molecules, we typically see two products. However, in most cases, we normally see both a major product and a minor product. The major product is typically the rearranged product that is more substituted (aka more stable). The minor product, in contract, is typically the normal product that is less substituted (aka less stable).
hydride shift mechanism
if SN1 rxn– carbocation forms- but before halide attacks- the hydrogen atom and carbocation can switch places- the Cl can now attack the more stable carbocation (more alkyl substituted)
- bc alkyl groups are electron donating - equalize charge
alkyl shift
Alkyl Shift acts very similarily to that of hydride shift. Instead of the proton (H) that shifts with the nucleophile, we see an alkyl group that shifts with the nucleophile instead. The shifting group carries its electron pair with it to furnish a bond to the neighboring or adjacent carbocation. The shifted alkyl group and the positive charge of the carbocation switch positions
gas-liquid chromatograph
-sample in gaseous form, passes through a liquid or solid stationary form
- mobile= gas carrier
- stationary= liquid
If a solution containing the compounds shown in Figure 4, is injected into a gas-liquid chromatograph, the first peak observed in the gc trace is attributable to which compound?
A.2-Methyl-2-butanol
B.2-Methyl-2-butene
C.2-Chloro-2-methylbutane
D.2-Bromo-2-methylbutane
butene- bc bc lowest molecular weight and also weakest intermolecular forces, so will travel the fastest and be the first peak
GLC seperation principle
-solubility in the stationary liquid phase - higher intermolecular forces
a solution sample that contains organic compounds of interest is injected into the sample port where it will be vaporized. The vaporized samples that are injected are then carried by an inert gas, which is often used by helium or nitrogen. This inert gas goes through a glass column packed with silica that is coated with a liquid. Materials that are less soluble in the liquid will increase the result faster than the material with greater solubility.
The combination of gas chromatography and mass spectrometry is an invaluable tool in the identification of molecules.
what’s D in a molecule
deuterium - represented as a D- it is an isotope of hydrogen with masss number 2
is D higher priority than H ?
yes - they have same atomic number, so break the tie based on mass, which D is higher
SN2 inversion drawing / r–> s
so to draw the molecule- we put the incoming group on the opposite side -> put it on the stick and keep the other substituents exactly as they are
- assuming that the priorities are the same (OH was highest before, and incoming group is now th highest) then if it was S before- now it is R
Isotopic substitution
is a useful technique due to the fact that the normal modes of an isotopically substituted molecule are different than the normal modes of an unsubstituted molecule, leading to different corresponding vibrational frequencies for the substituted atoms.
- adding an isotope to the compound as a tracker
- O-18 (meant it was isotopically labeled, not that it had 18 carbon LOL)
ohms law
V=IR
index of refraction equation
n=c/v
The intensity of the radiation emitted by the oxygen sensor is directly proportional to the:
A.propagation speed of the radiation.
B.wavelength of the radiation.
C.polarization of photons emitted.
D.number of photons emitted.
D - intensity= number of photons
intensity= energy/time
energy proportional to number of photons
E of a single photon = hf
the more photons = the more energy
THz
tera- hertz = 10^12
1/16 in percent
0.06= 6%
1/3, 1/4, 1/5 1/8, 1/9, 1/10
- 33
- 25
- 2 (1/5)
- 16
- 14
- 125 (1/8)
- 111
- 1
1/12,
1/15
1/20
- 08
- 06
- 05
1/20
0.05
bc 1/10= 0.1 —> and 20 is twice as big, so makes this number twice as small
adding fractions
bottom have to be the same, add the top and keep bottom
multiplying fractions
multiply the top and then the bottom, simplify
What is the work generated by a healthy adult who circulates 9 L of blood through the brachial artery in 10 min?
A.2 kJ
B.12 kJ
C.20 kJ
D.120 kJ
1st- 9L/10mins= 9000ml/10mins = 900ml/1min which is flow rate
2nd- on graph this equals 200 W of power
P= w/t so W= Px t
(I got to here but forgot to use the time in the question- it asks in 10` mins- which is 600s)
W= 200 x 600 = 120000 J
NOTE: 1 W= J/s
J= N x m
Which amino acid residues were incorporated into Compound 1 to promote the adhesion of cells on the scaffold surfaces?
A.Arg and Gly
B.Cys and Gly
C.Cys and Asp
D.Asp and Arg
D- asp and arg
as can be seen on the structure of the peptide provided, and the description of the roles of the various residues provided in the passage.
Why is the velocity of blood flow slower in capillaries than in arteries?
A.Capillary walls are more elastic than arterial walls.
B.Capillaries have less resistance to blood flow than arteries.
C.The total cross-sectional area of capillaries exceeds that of arteries.
D.Blood pressure is higher in the capillaries than in arteries.
total cross-sectional area of cap exceed that of arteries
- this is due to continuity equation
A1v1= A2v2
so if total area increases, v must decrease!
(remember it is the total area not the diameter of the arteries) - bc total blood flow in closed system must remain constant
this is also why vein blood is small - larger diameter
- remember that total blood flow in the circulatory system must remain constant!
why do vasoconstrictors increase velocity
bc they decrease total cross-sectional area
and due to continuity equation if A decreases, v must increase
Which of the following types of orbitals of the central atom are involved in bonding in octahedral compounds?
A.sp
B.sp3
C.p
D.d2 sp3
D - which I had put first!
octahedral have 6 sigma bonds- so it needs 6 hybridized orbitals and no lone pairs
octahedral compound
six ligands symmetrically around central atom
- example Mo(Co)6
retinal is hydrophobic or hydrophilic?
phobic! bc even though it has an OH- the entire rest of the molecule is C-H and very hydrophobic!
lipases?
hydrolyze fatty acids DUH
at pH=7, what amino acids are charged?
2 negative= acidic=Asp (D) and Glu (E)
3 positive= basic= lys (K), his (H), arg (R)
in biochem mutant protein studies what does R33G mean?
R (arg) at position 33 is mutated to G (gly)
-this is important!
Which type of bond is formed by glycogen synthase upon release of UDP?
A.α-1,4-Glycosidic bond
B.α-1,6-Glycosidic bond
C.β-1,4-Glycosidic bond
D.β-1,6-Glycosidic bond
A- a-1, 4 glycosidic bond
-this is main chain formation/linkage of glycogen
glycogen structure
a-1,4 linear bonds and then approx. every 10 there is a branch which is an a,1,6 glycosidic bond
Each of the following equations shows the dissociation of an acid in water. Which of the reactions occurs to the LEAST extent?
A.HCl + H2O → H3O+ + Cl−
B.HPO42− + H2O → H3O+ + PO43−
C.H2SO4 + H2O → H3O+ + HSO4−
D.H3PO4 + H2O → H3O+ + H2PO4−
B –> bc HPO4 ^2- has a high negative charge and so dissociation o it will occur to a less extent (more negative)
In the above figure, an object O is at a distance of three focal lengths from the center of a convex lens. What is the ratio of the height of the image to the height of the object?
A.1/3
B.1/2
C.2/3
D.3/2
B- because the ratio of the image height to the object height is equal to the ratio of the lens-image distance to the object-lens distance.
thin lens equation
1/d0 +1/di = 1/f
the ratio of the image height to the object height is equal to?
the ratio di/do
image distance/ object distance
When a strip of Zn is placed in a beaker containing 0.1 M HCl, H2(g) evolves. If a strip of Al is placed in a beaker containing 0.1 M HCl, does H2(g) evolve?
A.Yes; Al is reduced and H+(aq) is oxidized.
B.Yes; Al is oxidized and H+(aq) is reduced.
C.No; Al is reduced and Cl-(aq) is oxidized
D.No; Al is oxidized and H2O(l) is produced.
B- yes H2 (g) evolves, Al is oxidized (losing e-) and H+ is reduced (gaining electrons) - think H+ (no electrons) to H-H (has more)
Al(s) —> Al+ + e (as anode)
- here had to look at the table which stated that a new solid forms when Al(s) is mixed with Zn2+ –> reasonable to issue that Zn2+ + e—> Zn(s) new solid - therefore, Al was more susceptible to oxidization, so in the question we can assume that it will also get oxidized - thus H reduced
A circuit similar to that in Figure 2 is set up in which X = Pb, Xn+ = Pb2+, Y = Cu, and Ym+ = Cu2+. Will an oxidation–reduction reaction occur spontaneously?
A.No; E°cell = –0.212.
B.No; E°cell = +0.212.
C.Yes; E°cell = –0.466.
D.Yes; E°cell = +0.466.
Pb2+(aq) + 2e– → Pb(s) E°red = –0.127 V
Reaction 1
Cu2+(aq) + 2e– → Cu(s) E°red = +0.339 V
Reaction 2
should have gotten this one right- just messed up signs
- but the more positive one will be reduced, the other oxidized- so flip sign
then to get Ecell= add them = +.466
a positive Ecell means?
a spontaneous rxn, delta G and E are always opposites!
negative G and positive E
A circuit similar to that in Figure 2 is set up. It has a potential of 2.0 V. Assume that the resistance in the circuit is negligible compared to that of the lightbulb. Approximately how much current passes through the lightbulb?
A.0.5 A
B.1.0 A
C.2.0 A
D.4.0 A
V=IR
I= V/R = 2.0/0.5
2.0 x 2= 4 A
The equilibrium
BaCrO4(s) Ba2+(aq) + CrO42–(aq)
exists in a saturated aqueous solution of BaCrO4. Dissolution of Na2CrO4 in a saturated aqueous BaCrO4 solution would:
A.have no effect on the position of this equilibrium.
B.shift this equilibrium left.
C.shift this equilibrium right.
D.shift this equilibrium first right and then left.
Don’t overthink it! if you add more CrO4 it will switch left
- I mistook this for common ion effect
- oh wait no it is! common ion effect= reduces the solubility of BaCrO4
- le chapeliers principle
common ion effect
literally just le chattier principle in effect- when ions are already present- molar solubility of the salt is reduced, cause system shifts left- but Ksp just chills- it remains constant (bc think of it like le chatilier principle- it still has its favourite equilibrium spot, but when stress is added it shift away to receive stress- but Ksp doesn’t change- it doesn’t set a new ksp)
Ksp
- law of mass action applied to solution at equilibrium - when a solution is saturated, the solute concentration is at a MAX, it is dynamically stable
- equillibrium constant for saturated solution
Ksp= [A^n+]^m [B^m-]^n
- no denomenaor - bc its a pure solid so cancel
law of mass action
just Keq —> which is the ratio of products to reactants at equilibrium, with each species raised to its coefficient
law of mass states that if a system is in equilibrium, the the following ratio is constant
Keq= products/reactants (raised to coefficients)
what can be used to determine if a solution is saturated
compare IP to Ksp
what can be used to determine if a solution is saturated
compare IP to Ksp
how does Ksp react to increasing temperature for non-gas solutions vs gas solutions (tricky- but you got it!)
for non-gas—> increasing temp= increase ksp (more dissolved)
but for gas= increasing temp= decrease in gas solutes (why?- bc kineticc energy of gases increase- its molecules have a greater tendency to escape the attractive forces that were holding them together)
Ksp of gas when pressure increases, and an example
Ksp increases with increasing pressure- for example- when deep sea diving = more pressure= gas becomes more soluble= more N (from air) will dissolve into blood
describe dynamic equilibrium
most reversible reactant in a closed system will no go all the way to completion and eventually the system will settle into a state where the reverse and forward reactions are happening at equal rates- the concentrations of products and reaction will be CONSTANT —> not EQUAL- constant
describe equilibrium I terms of entropy
the system settles into a place where/ will reach equilibrium when the systems entropy- or energy distribution- is at a max! and Gibbs is at a minimum
in an isolated system at equilibrium how can you increase entropy
you can’t! at equilibrium the system cannot increase - it is at its MAX!
how is law of mass related to rate law???
ok so, at equilibrium we are saying that the rate of the forward and reverse reactions are equal
so do that: kf [A] = kr [B] [C]
Kf/kr =[B] [C] / [A]
therefore keq is just another way of saying kf/kr
What volume of a 0.120 M CaI2 solution would contain 0.078 mol of the solute?
A.35.0 mL
B.65.0 mL
C.350 mL
D.650 mL
D - 650 ml
bc 0.078 / .120
= think 0.1= 1/10 and 0.05 = 1/20 - so around 1/12
and 0.120 = 0.125= 1/8
1/12/1/8
Which measurement unit CANNOT be used to express power?
A.kg•m2 •s2
B.J•s-1
C.ft•lb •s-1
D.W
power = W = j/s
so only A is wrong
pervasiveness
prevalent, extensive, penetrating
- spreading widely
CH is found in
- lipid rafts
- plasma membrane microdomains enriched in cholesterol and sphingolipids that are involved in the lateral compartmentalization of molecules at the cell surface.
endomembrane system
the continuous organelles that are suspended in the cytoplasm - nuclear membrane, ER, Golgi, lysosomes, vesicles
median
is the midpoint- where half data points are greater and half are smaller
mode
most frequent number
mean
average of the set
episodic memory
memory that can be explicitly recalled- of events
An immigrant teen stops participating in the ethnic customs of his family and instead identifies with the dominant culture of the new country by dressing, speaking, and acting like teens from that culture. In this scenario, the teens of the new country’s dominant culture become which type of group for the teen?
A.Assimilated group
B.Reference group
C.Majority group
D.Peer group
B- reference group
“self-identity” - individuals often emulate the attitudes and behaviours of groups that they admire and want to join, sociologist refer to these groups ass reference groups
The scenario in the question suggests that the teen constructs an identity, through modifying his behaviors (dressing, speaking, acting), to match that of teens from the dominant culture of his new country.
majority group
is the social group considered to have the most power in a particular place (and sometimes the most members). On the other hand, a minority is any category of people distinguished by either physical or cultural difference that a society has subordinated.
Because cultural liaisons work closely with physicians and are advocates for patients, which phenomenon are cultural liaisons most likely to experience?
A.Network redundancy because of the amount of people with whom they come into contact
B.Homogeneity because they will see the same patients over and over
C.Role strain because of their collegiality with physicians and their responsibility to patients
D.Role conflict because of their status as a non-medical professional in a clinic setting
Role strain is the tension that results from competing demands within the context of a single role. As applied to the question, the tension that the cultural liaison experiences is between different responsibilities within the same occupational role.
mixed-methods study
The research design employs both a quantitative component (the statistical analysis of the total claims) and a qualitative component (the in-depth analysis of a subset of cases). Bringing together quantitative methods and qualitative methods is referred to as mixed methods in sociology.
Which research methodology involves the extended, systematic observation of a complete social environment?
A.Comparative methods
B.Ethnographic methods
C.Experimental methods
D.Survey methods
B. ethnographic methods
Ethnographic methods are a research approach where you look at people in their cultural setting, with the goal of producing a narrative account of that particular culture, against a theoretical backdrop. … How they interact with one another, and with their social and cultural environment.
mixed-methods design
A mixed methods design is characterized by the combination of at least one qualitative and one quantitative research component. … Mixed methods research is the type of research in which a researcher or team of researchers combines elements of qualitative and quantitative research approaches
