ochem mcat definitions

  1. optical rotation of zero and equal mixture of two enantiomers
    racemic mixture
  2. If all of the chiral centers are of opposite R/S configuration between two stereoisomers, they are _______.

    If at least one, but not all of the chiral centers are opposite between two stereoisomers, they are _______.

  3. A substance that is a single, pure enantiomer (i.e., has 100% ee) is called homochiral or optically pure.
  4. A ________ is a non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereogenic centers, the molecule is not chiral. It is "superposable" on its mirror image.
    meso compound or meso isomer
  5. In stereochemistry, an _____ is one of a pair of stereoisomers. The two isomers differ in configuration at only one stereogenic center.

    anomer differ at the anomeric carbon
  6. If one enantiomer has a melting point of 80 the other will have _____

    If one enantiomer has optical rotation of +45 degrees the other has ____
    80 (same physical properties) 

    -45 degrees
  7. The process of separating two enantiomers is ______
  8. Enantiomer A has an absolute configuration of R and optical rotation of +87, what is enantiomer B's absolute configuration and optical rotation?
    S and -87
  9. A mixture of two racemic compounds will give a mixture of _____ stereoisomers?
  10. Longer carbon chain means ______ hydrophobic
    more hydrophobic
  11. Higher retention factor means
    it elutes first (non polar) in thin layer chromatography

    polar interact with silica gel

    High performance chromatography

    Column chromatography

    But in reverse HPC polar elute first
  12. IR:

    Carboxylic acid:
    aldehyde C-H:
    Ester: 1735 (which could be part of carboxylic acid since ketones are around 1700)

    Alcohol/OH: 3100-3300 (broad) alcohol typically 3350

    • Ketone: 1750
    • Alkene: 1650
    • NH: Sharp 3300
    • Carboxylic acid: 3000
    • Aldehyde C-H: 2700-2800
  13. HNMR n + 1 rule

    A signal will be neighboring carbon hydrogens plus 1. 

    ex. doublet has one adjacent hydrogen + 1 to make doublet.
  14. Whats the degrees of unsaturation formula and what two things count as degree of unsaturation?
    2C + 2 + N - H - X / 2

    ring and double bond
  15. SN2 reactions operate by 

    ____ order kinetics

    1°>2°>3° reactivity sequence 

    complete inversion of stereochemistry 

    does it have rearrangement?
    second order 

    complete absence of rearrangement
  16. SN1 or SN2

    ____ depends on substrate concentration only (rate of leaving group loss.?

    Depends on substrate concentration and concentration of nucleophile cuz it's one step_____

    Both SN1 and SN2 depend of solvent and temperature.
    SN1 depends on substrate concentration (rate of leaving group loss)

    SN2 cuz it's one step
  17. SN2 reactions proceed ______ with increased steric hindrance/ substituent size.

    SN1 reactions proceed ____ with increased steric hinderance/ substituent size.

    faster cuz SN1 prefer more stable carbocation tertiary > secondary >> primary
  18. alcohol --------> ester

    -----> is ______
    acetic anhydride
  19. what compound has IR spectrum of 1735cm -1
    ester = 1735 cm-1
  20. strongest acid is one with strongest electron withdrawing group closest to molecule.

    Cl > OH
  21. LiAlH4 reduces acids (carboxylic acids) to _____
  22. alcohol + carboxylic acid =
  23. only primary alcohols can be oxidized to carboxylic acids
  24. proton between two carbonyl groups is highly acidic
  25. The pI (isoelectric point) for enantiomers is _____
    the same 

    same physical properties for enantiomers
  26. How to determine how many stereoisomers carbohydrates have, what formula?

    n - number of chiral centers
  27. Positive test for benedicts test would need a reducing sugar that had a ketone or aldehyde at first or last carbon to reduce copper and be oxidized in process.

    If both ends have carboxylic groups it won't work
  28. Meso compounds (achiral) must have how many chiral centers.
    any even number greater than or equal to 2.
  29. Base - Adenine, Guanine, Cytosine, Thymine


    Nucleosides: adenosine, guanosine, thymidine, cytidine

    Nucleotides: Base + ribose + phosphate

    • adenosine tri phosphate
    • guanosine tri phosphate
    • cytidine tri phosphate
    • thymidine tri phosphate
  30. monosaccharide forumula
    Cn (H2O)n

    n - any number usually from 3-9

    EX- C3H6O3 - triose

    C9H18O9 - Nonose
  31. Cholesterol plasma membrane buffer

    At low temperatures, cholesterol _____ membrane fluidity
    by preventing membrane lipids from packing close together.
    At high temperatures, cholesterol ______ membrane fluidity.

  32. how to look at aldol in your head:

    the alpha proton becomes a double bond and you wipe off the ketone from the other molecule and attach there
  33. reactants - pka 25

    products - pka 35

    which is favored?
    products - weaker acid (high pka)
  34. John HIO biochemistry 

    Hydrazone, Imine, Oxime, similar structure (NH2/NHR, R/H, OH)
  35. Na2Cr2O7 / H2SO4, H2O (Jones) can oxidize _______ and _______

    Tollens reagent can only oxidize _______
    alcohols and aldehydes 

  36. primary amine + ketone = _______
  37. _________ 4n + 2 pi bonds

    for aromaticity, n can be any integer
    Huckel's rule
  38. Steric number is ______
    sigma bond + lone pair
  39. Beyonce at the VMF

    what this mean?
    Boiling point inverse to Vapor pressure, Melting point, and Freezing point
  40. Inductive effects on carboxylic acid derivatives making them more reactive is more electronegative atoms closer to carbonyl to give carbonyl a partial positive (EW)

    Resonance stability (ED) to make things less reactive is having a resonance and no other competing resonance and also the carbonyl carbon and ED atom in same period.

    ex- amide less reactive than carboxylic acid with OH because N is less electronegative than O and will be more willing to donate as oppose to withdraw it's electrons for resonance stability and N in same period as C also so good p orbital overlap.
  41. coenzyme (non protein organic cofactor) binds apoenzyme (inactive) = ________
    prosthetic group
  42. 0 order units K _____

    1st order ____

    2nd order ____

    3rd order _____
    0 = M/s

    1 = s-1

    2 = s-1 * M-1

    3 = s-1 * M-2
  43. intermediate vs catalyst

    reactant then on product side in next step ____

    product side then reactant side in next step ____

  44. Spontaneous or Non-Spontaneous and push reaction to right/products or left/reactants ?

    K > Q
    Q > K
    K = Q

    K > 1 
    K < 1
    K = 1
    K > Q = Spontaneous -ΔG/ push to products/right

    Q > K = Non-spontaneous +ΔG/ push to left/reactants

    K = Q = ΔG = 0

    K > 1  = spontaneous / -ΔG / push to right/products

    K < 1 = non-spontaneous / +ΔG / push to reactants/left

    K = 1 = ΔG = 0
  45. What's the 0th law of thermodynamics?

    What's the 1st law of thermodynamics?

    2nd law thermo?

    expansion - work done by gas (-w)
    compression - work done on gas (+w)
    0th law: If obj 1 in thermodynamic equilibrium with 2, and 2 is in thermoequilibrium with 3 then 1 is with 3, allow for universal temp scale

    1st law: Energy can't be created or destroyed only converted from one form to another. ΔU = Q + W

    • ΔU = Change in internal energy OF GAS
    • Q = Heat (-Q heat release/ +Q heat added)
    • W = Work (-W work done by gas/ +W work done on gas)

    • adiabatic ΔU = 0
    • isothermal Q = 0
    • isovolumetric / isochoric W = 0
    • --------------------------------

    2nd law

    Heat flow from hot to cold and will never be seen flowing from cold to hot spontaneously
  46. Combustion formula:

    CxHy + O2 ---> ____CO2 + ____H2O

    C5H12 ---->  _____ + ______
    CxHy + O2 ---> xCO2 + y/2 H2O


    C5H12 ----> 5 mol CO2 + 6 mol H2O
  47. more stable trans both substituents equatorial (sideway not down which is axial)

    more stable cis bulkier substituent equatorial
  48. A catalyst that has a different phase (s, l, g) than the reactants it catalyzes is called _____
    heterogeneous catalyst

    homo would be same phase like gas to gas or liquid to liquid
  49. H2O + H2O = H3O+ is an example of _____
    autoionization - same substances react to form ion.
  50. constant velocity = acceleration is zero
  51. Newton 1st law ______

    Newton 2nd law ______

    Newton 3rd law ______
    Newton 1st law- object keeps moving unless a force stops it from moving

    Newton 2nd law - F = ma (kg * m/s^2)

    Newton 3rd law - When a force is applied there's an equal reaction of force in opposite direction opposing that force that's equal like for example with pushing a desk
  52. object keeps moving unless a force stops it from moving ______
    Newton 1st law-
  53. F = ma (kg * m/s^2)

    what is this?
    Newton 2nd law -
  54. When a force is applied there's an equal reaction of force in opposite direction opposing that force that's equal like for example with pushing a desk
    Newton 3rd law -
  55. _____ pressure is transmitted undiminished to every portion of the fluid and to walls of the container

    P = F/A
    F1D1 = F2D2

    Small force applied to small area over large distance provides a large force to a large area over a small distance

    SG of 0.2 means 20% object submerged in water

    SG = weight of fluid displaced
    SG > 1 MEANS _____
    pascals law

    object sinks
  56. Poiseuille's law

    Volume flow rate = ΔP*pi*R^4 / 8NL

    N= Viscosity
    L= length of tube

    increase ΔP = increase volume flow rate

    increase length of tube and viscosity = decrease volume flow rate

    _____ water molecules attracted to each other

    ____ water molecules attracted to something else (like tube so meniscus)

    * water level higher where fluid travels faster

  57. formula for temp in C

    formula for temp in F
    Tc = Tf-32 (5/9)

    Tf = Tc(9/5) + 32
  58. Which has more pressure and less volume, real gas or ideal gas?

    Ideal has operates under ____ temp and ___ pressure
    ideal gas more pressure and less volume than real gas

    (volume occupied by gas molecules negligible in ideal gas, collisions are elastic no KE lost, all KE related to pressure, gas molecules don't touch except during collision)

    ideal gas - high temp / low pressure
  59. electrostatic force = kq1q2/r^2

    electric field = kQ/r^2

    electric potential = kQ/r
  60. resistivity = replay for formula

    whats the formula?

    what does increasing length do to resistance?
    R = p(L/A)

    p = resistivity which if it increases increases resistance

    copper gold silver are conductors with little resistance cuz they metals

    non metals are insulators- more resistance

    increasing length increases resistance cuz current would have to travel farther

    increasing area decreases resistance cuz there's a bigger area to flow through
  61. volmeter need huge resistance (ideally infinity) since hooked up in parallel and u want as much current to flow thru resistor and voltmeter in series would block current

    ammeter hooked up in ____ because it has ___ resistance
    ammeter hooked up in series little resistance.

    ideal ammeter has zero resistance
  62. Does increasing charge increase capacitance? 

    increase capacitance by making pieces of metal _____

    place piece of metal closer or further apart increase capacitance?
    No, increasing charge does not increase capacitance because voltage would increase and ratio would be same C = Q/V



    • C = eo A/d
    • c = eo K A/d

    dielectric k is 1 for air and vaccum and anything else is larger
  63. two formulas for energy stored in a capacitor

    HINT: If you use C you can see (c) the V^2
    E = 1/2CV^2

    E = 1/2QV
  64. with dielectric how you increase capacitance

    with battery - increase charge

    w/o battery decrease voltage

    C = Q/V
  65. right hand rule proton

    left hand rule electron

    thumb -
    pointer -
    middle finger -
    • thumb - force
    • pointer - qv - velocity and charge or current
    • middle finger -magnetic field

    magnetic force = qvB
  66. less substituents = _____ heat of hydrogenation

    substituents equal more steric hinderance = ______ heat of hydrogenation

    similar changes in heat of hydrogenation and heat of combustion
    higher heat of hydrogenation

    higher eat of hydrogenation (cis > trans heat of hydrogenation if substituents equal)
  67. ______ enhance the RNA pol and promoter interaction during transcription

    _____ located on the DNA chromosome; activators bind here and loop DNA to bring specific promoter to initiation complex to enhance transcription of genes. activator interacts with mediator complex to recruit RNA pol and general TFs.

    TFs transcription factors bind to ____


  68. _____ bind to silencers located on DNA strand
  69. proto-oncogene vs oncogene

    which one cancer which one normal
    proto-oncogene - normal

    oncogene - cancer
  70. ______ mutation new AA same type as original (Arg -> His both basic)

    _____ mutation new AA different type (Arg -> Asp, basic to acidic)

    ____ A -> G purine to purine

    ____ A --> T purine to pyrimidine

    ____ gene on one chromosome swapped for gene on another 

    ___ gene one same chromosome swapped
    conservative mutation 

    non-conservative mutation




  71. sanger sequencing - set the base pairs for coding region starting from bottom + to top - (5` to 3`)
  72. Type ______ enzymes target modified (e.g. methylated, hydroxymethylated) DNA.

     Type _____ enzymes cleave within or at short specific distances from their recognition sites and often require magnesium (Mg2+)

     Type _____ enzymes cleave at sites a short distance from their recognition sites and require ATP (but do not hydrolyze it). S-adenosyl-L-methionine stimulates this reaction, but is not required.

    Type ______ enzymes cleave at sites remote from the recognition site; they require both ATP and S-adenosyl-L-methionine to function.



  73. _____ used to simultaneously analyze the gene expression profiles of 1000s of genes to study disease 

    ______ - used to assay location of specific DNA sequence
    micro arrays

    Florescence in situ hybrid
  74. which is more muscular/thick, atria or ventricles?

    which is more muscular/thick/elastic, veins or arteries?

  75. - stimulates bile production by liver

    - secreted by s. intestine/duodenum

    - stimulates pancreas to release H2O and HCO3- to neutralize HCl

    - Inhibits gastrin to inhibit HCl release
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ochem mcat definitions