LUBDUBB

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Ok, let's play...

Originally posted by Cerberus


Question 1:

What type of solvent would be best for favoring Sn1?

Polar protic solvents tend to stabilize the carbocation intermediate, increasing the rate of reaction.



Question 2:

Which one is more soluble in water, Oxygen or Carbon dioxide, and why?
 
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Cerberus

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Originally posted by LUBDUBB
Ok, let's play...



Polar protic solvents tend to stabilize the carbocation intermediate, increasing the rate of reaction.



Question 2:

Which one is more soluble in water, Oxygen or Carbon dioxide, and why?

This is just a guess but I am going to guess that it is CO2 because CO2+H2O <-> H2CO3<->H+ + HCO3-

A defect in nervous system formation could most likely be attributed to a defect in which germ layer?
 

farley is god

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Originally posted by Cerberus
This is just a guess but I am going to guess that it is CO2 because CO2+H2O <-> H2CO3<->H+ + HCO3-

A defect in nervous system formation could most likely be attributed to a defect in which germ layer?

the ectoderm gives rise to the nervous system.

hmm...

reduction of a ketone to an alcohol will be marked by an appearance of ______ and disappearance of ______ on an IR spectrum.
 

Nuel

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Originally posted by farleyisgod
the ectoderm gives rise to the nervous system.

hmm...

reduction of a ketone to an alcohol will be marked by an appearance of ______ and disappearance of ______ on an IR spectrum.

dissappearance of carbonyl stretch at approx. 1700cm-1 and and appearance of OH stretch at 3500cm-1. this was too easy. the question on bacterial vs. eukaryotic oxidative respiration was more interesting.
 

sdnstud

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Originally posted by Nuel
In response to cerb:

What is the sufficient condition for chirality?

4 different substituents attached to a sp3 atom


how does an increase in temperature affect the tone played on the piano?
 

Nuel

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Originally posted by sdnstud


how does an increase in temperature affect the tone played on the piano?

Increase in temperature will increase the speed of ambient air, therefore the sound waves will travel faster and the tone would be distorted--as well as the pitch.
 
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jhk43

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Originally posted by Nuel
Your answer is wrong. An sp3 chiral center is only a necessary condition for chirality, not sufficient.

thats a cheapie!

if a fetus lacks just testosterone receptor, but has an XY genotype, what is its internal (m or f or none) and external (m or f or none) genitalia?
 

Nuel

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Originally posted by jhk43
thats a cheapie!

if a fetus lacks just testosterone receptor, but has an XY genotype, what is its internal (m or f or none) and external (m or f or none) genitalia?

It's not a cheapie. Does allene C=C=C have a chiral center? No, but it a chiral molecule. So the sufficient condition is that the molecule not have a mirror plane of symmetry.

In response to your question, no internal or external genitalia.
 

LUBDUBB

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Originally posted by Nuel
No difference is expected. Bacterial plasma membrane performs the same function as mitochondria.

36 for eukaryotes, 38 for prokaryotes.

In Eukaryotes, the two NADH made in glycolysis must be passed across the mitochondrial membrane actively. This yields 2 ATP per NADH for a total of 4 ATP, instead of 3 atp per NADH as is expected of the NADH generated in the mitochondria.

In prokaryotes, because the two NADH do not have to cross any mitochondrial membrane, they yield 3 atp per NADH.
 

LUBDUBB

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Originally posted by Cerberus
This is just a guess but I am going to guess that it is CO2 because CO2+H2O <-> H2CO3<->H+ + HCO3-


Well more completely, the oxygen in H20 is slightly nucleophillic so it will attack the carbon on CO2.
 

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Originally posted by jhk43
thats a cheapie!

if a fetus lacks just testosterone receptor, but has an XY genotype, what is its internal (m or f or none) and external (m or f or none) genitalia?

If the fetus lacks testoesterone receptors it will have female genitalia (external and internal, perhaps underdevelopped) and will be sterile...cuz it'll be almost equivalent to XO and will develop by default as female b/c the testerone isn't sensed.

Ok, here's a rather lengthy Q ;)

Who can explain beat frequencies, harmonics and all that jazz?
 

Nuel

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Originally posted by LUBDUBB
36 for eukaryotes, 38 for prokaryotes.

In Eukaryotes, the two NADH made in glycolysis must be passed across the mitochondrial membrane actively. This yields 2 ATP per NADH for a total of 4 ATP, instead of 3 atp per NADH as is expected of the NADH generated in the mitochondria.

In prokaryotes, because the two NADH do not have to cross any mitochondrial membrane, they yield 3 atp per NADH.

I knew someone was to comment on this. I wanted to add to this but desisted.

The eukaryotic yield is theoretically 36 or 38 ATP depending at what level NADH will deliver its electrons on the ETC. Even this is contested among scientists. MCAT won't test this detail.
 

jhk43

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Originally posted by DrSal
If the fetus lacks testoesterone receptors it will have female genitalia (external and internal, perhaps underdevelopped) and will be sterile...cuz it'll be almost equivalent to XO and will develop by default as female b/c the testerone isn't sensed.

Ok, here's a rather lengthy Q ;)

Who can explain beat frequencies, harmonics and all that jazz?

beat frequency is the numerical difference between any two waves.

harmonics is the resonance frequency that is characteristic of the system, depending on things like length, wavelength (and indirectly tension, bulk modulus, velocity)



Consider the rxn between Ester and NaOH. Will the reaction favor nuc. substitution or aldol addition? what about between ketone and NaOH
 

Nuel

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Originally posted by DrSal
If the fetus lacks testoesterone receptors it will have female genitalia (external and internal, perhaps underdevelopped) and will be sterile...cuz it'll be almost equivalent to XO and will develop by default as female b/c the testerone isn't sensed.

Ok, here's a rather lengthy Q ;)

Who can explain beat frequencies, harmonics and all that jazz?

I erroneously ignored the effect of female hormones. You could be right . . . let jhk confirm.
 

LUBDUBB

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Originally posted by DrSal
If the fetus lacks testoesterone receptors it will have female genitalia (external and internal, perhaps underdevelopped) and will be sterile...cuz it'll be almost equivalent to XO and will develop by default as female b/c the testerone isn't sensed.


No testosterone --> no wolffian ducts --> no internal male genitals.

If the testis still produce MIS, then Mullerian system (internal female genitalia) are also inhibited.

As for external genitalia, if no testosterone, then xy will develop into incomplete female.

Hope I'm right.
 

LUBDUBB

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Originally posted by Nuel
I knew someone was to comment on this. I wanted to add to this but desisted.

The eukaryotic yield is theoretically 36 or 38 ATP depending at what level NADH will deliver its electrons on the ETC. Even this is contested among scientists. MCAT won't test this detail.

You are absolutely right.
 
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jhk43

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Originally posted by LUBDUBB
No testosterone --> no wolffian ducts --> no internal male genitals.

If the testis still produce MIS, then Mullerian system (internal female genitalia) are also inhibited.

As for external genitalia, if no testosterone, then xy will develop into incomplete female.

Hope I'm right.

External Female, No Internal organs.

Y chromosome-->testicles formed-->MIF and testosterone. MIF prevents female internal organs. No testosterone receptor means no internal or external male organs. However, nothing prevents the default external female genitals from forming.

well done lubs
 

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Q: If a rocket take off at an initial velocity of 100 m/s, 75 degrees of the horizontal, and its engine stops working after 11 seconds, what is the maximum height the rocket achieves? (had a similar problem like this on real deal last year :O)
 

Cerberus

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Originally posted by krull
Q: If a rocket take off at an initial velocity of 100 m/s, 75 degrees of the horizontal, and its engine stops working after 11 seconds, what is the maximum height the rocket achieves? (had a similar problem like this on real deal last year :O)

My guess is this, in the first 11 seconds the acceration due to gravity can be neglected due to the engine.
So

y=11*sin75*100
y=1062

then after that point,

v^2=v^2(initial)+2ad

0=(sin75*100)^2-2*10*y

y=466

So the total distance achieved is

1062+466 = 1528m
 

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:clap: :thumbup:

Here is another one I had.

What is the length constant found in cells due to a local depolarization?
 

jhk43

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Originally posted by krull
Q: If a rocket take off at an initial velocity of 100 m/s, 75 degrees of the horizontal, and its engine stops working after 11 seconds, what is the maximum height the rocket achieves? (had a similar problem like this on real deal last year :O)

i'll assume sin 75 is given...or you can just figure out that sin 60 = root 3/2 and sin 1 =1--->sin75= ~0.9

initial vo= 100*sin75 = 90 m/s
height achieved after 11 seconds: D=RT = 90*11= 990m

at that point, projectile motion begins
intial v = 90m/s.
final v =0.

Vf^2=Vi^2 +2as

90^2=0 + 2(10)s
s=400

Total distance 990+400 = 1390m
 

krull

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heh, never heard of the length constant? That's the length a typical conductance length a local response in cells typically has
 

jhk43

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Originally posted by Cerberus
My guess is this, in the first 11 seconds the acceration due to gravity can be neglected due to the engine.
So

y=11*sin75*100
y=1062

then after that point,

v^2=v^2(initial)+2ad

0=(sin75*100)^2-2*10*y

y=466

So the total distance achieved is

1062+466 = 1528m


or u can use a calc :)
 

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Originally posted by krull
heh, never heard of the length constant? That's the length a typical conductance length a local response in cells typically has

Nope...never heard of it...

Q: which requires a greater escape velocity (to escape earth)? when rocket is launched at the equator, north pole or somewhere in between?

This was on the actual mcat i took 2 years back :)
 
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jhk43

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Originally posted by sdnstud
Nope...never heard of it...

Q: which requires a greater escape velocity (to escape earth)? when rocket is launched at the equator, north pole or somewhere in between?

This was on the actual mcat i took 2 years back :)

i believe Radius is max at the equator, min at the N pole..

F=GMm/R^2

g~M/R^2

since g~1/R^2, g is max at smaller radius, so escape velocity max @ north pole?
 

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Consider the rxn between an Ester and NaOH. Will the reaction favor nuc. substitution (COOH) or aldol addition/condensation? what about between ketone and NaOH? What about Acid Chloride and NaOH?
 

krull

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Originally posted by jhk43
Consider the rxn between an Ester and NaOH. Will the reaction favor nuc. substitution (COOH) or aldol addition/condensation? what about between ketone and NaOH? What about Acid Chloride and NaOH?

A) nuc sub?

B) aldol addition

c) nuc sub

Q: This was a wierd one I had. Easy but weird. If an object is traveling a 100,000 m/s and it emits a flash of light which travels at a velocity of 186,000 m/s, what is the speed of the particle within the flash of light? (something similar to this)
 

jhk43

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Originally posted by krull
A) nuc sub?

B) aldol addition

c) nuc sub

Q: This was a wierd one I had. Easy but weird. If an object is traveling a 100,000 m/s and it emits a flash of light which travels at a velocity of 186,000 m/s, what is the speed of the particle within the flash of light? (something similar to this)

Relativity??

NO WAY!
speed of the particle relative to 186K M/S? i'm assuming its 86k, since relativity aint on the mcat v~[inverse (1+v^2/c^2)]


back to the ester + NaOH....kinda confused...when do carbonyls prefer substitution, and when do they prefer the alpha hydrogen reactions? I know that alpha hydrogen is increased with withdrawing group, so in these cases it will prefer nucleic substitution.

the O ester is electron donating, so the alpha hydrogen is less acidic than a ketone rite?


What is the order of alpha H acidity btw:
acid chloride, ester, cooh, aldehyde, ketone?
 

LUBDUBB

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Originally posted by jhk43
Consider the rxn between an Ester and NaOH. Will the reaction favor nuc. substitution (COOH) or aldol addition/condensation? what about between ketone and NaOH? What about Acid Chloride and NaOH?

Ester +NaOH is a saponification (base catalyzed hydrolysis)
R-COOR' + NaOH --> R--0-:Na+

Acid Chlroide + NaOH will hydrolzye the acid chloride back to the carboxylic acid.

Ketone + NaOH ...hmmmmm..well adding NaOH to an aldehyde/ketone forms the enolate ion. Now if we've got an aldehyde we can have an aldol condensation. I guess the ketone will also undergo aldol condesation but the eq concentrations will be minimal.
 

jhk43

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Originally posted by LUBDUBB
Ester +NaOH is a saponification (base catalyzed hydrolysis)
R-COOR' + NaOH --> R--0-:Na+

Acid Chlroide + NaOH will hydrolzye the acid chloride back to the carboxylic acid.

Ketone + NaOH ...hmmmmm..well adding NaOH to an aldehyde/ketone forms the enolate ion. Now if we've got an aldehyde we can have an aldol condensation. I guess the Ketone will also undergo aldol condesation but the eq concentrations will be minimal.


i'mma sittin next to lubby on d-day. :clap:
 

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Originally posted by jhk43
NaOH + Aldehyde/Ketone, does it ever form a COOH via substution? or just aldol addition?

Aldehydes and Ketones don't undergo nucleophilic substitution, except with amines to form imines.

Edit: I don't think they would form COOH via substitution because H and R are horrible leaving groups
 

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Ok, here's a rather lengthy Q ;)

Who can explain beat frequencies, harmonics and all that jazz? [/B][/QUOTE]

Not lengthy. Okay, beat frequencies are simple. The beat frequency is the difference between two frequencies, ie, 240 Hz and 242 Hz means beat frequency is 2 Hz. Not so tough. It's just periodic loudness variation when two similar pitches are sounded simultaneously. I could do the wave derivation, but it's much easier to just think of it this way. Think of it this way- if you have a tuning fork and clamp it, you decrease the frequency- it goes flat. Why? Because of angular acceleration. The tines are trying to vibrate but you just increased their moment of inertia, so they are now dissonant with another tuning fork of the same original frequency. That dissonance you hear is beating.
Harmonics:
initial frequency, with ONE node is referred to as the "fundamental frequency" also known as the first harmonic.
Simple: When you have an open pipe (antinode-antinode) or you're in the middle of a closed pipe (node-node) then ALL harmonics are allowed. To find the new frequency of the harmonic, just multiply the fundamental frequency by its integer (ie 2nd harmonic = 2 x fundamental frequency). For Node-Antinode conditions, only ODD harmonics are allowed because of boundary conditions. So you multiply by 1, 3, 5, 7 etc.
I can't explain Jazz. Sorry. :)

Okay, here's one:

If you are farsighted then your _____ point is too ______. You fix with a _________ lens.
If you are nearsighted, your ________point is too _______, and you fix it with a ________ lens.

Bonus: What is the sign of the power of the lens you use to fix each problem, respectively?
 

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Okay, here's one:

If you are farsighted then your _____ point is too ______. You fix with a _________ lens.
If you are nearsighted, your ________point is too _______, and you fix it with a ________ lens.

Bonus: What is the sign of the power of the lens you use to fix each problem, respectively? [/B]

If you are farsighted then your _focal____ point is too _behind the retina_____. You fix with a _converging________ lens.
If you are nearsighted, your focal point is too in front of retina, and you fix it with a diverging lens.

converging lenses, f=+, p=+
diverging, f=-, p=-


Would a histone protein be acidic or basic?
 

LUBDUBB

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quote:
--------------------------------------------------------------------------------
Originally posted by jhk43
E1 vs. Sn1. in which conditions does E1 win? Sn1 win?
--------------------------------------------------------------------------------


Originally posted by Persistence101
According to EK, elimination occurs when the nucleophile acts like a base. To avoid this, use a less bulky base.


Given a secondary or tertiary compound and a weak nucleophile (weak base),

E1 favored by high temps and bulky nucleophile.

A strong base (strong nuc) will force second-order kinetics.
 
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