Chem-Phys Flashcards
What is a stereospecific reaction
a reaction in which the stereochemistry of the reactant completely determines the stereochemistry of the product, without any other options
What is the thin lens formula
1/o + 1/i = 1/f
electromagnetic radiation is directly proportional to….
the number of photons emitted
Tera (T) SI unit prefix
10^12
Mega SI unit prefix
10^6
Giga SI unit prefix
10^9
Joules units
( kg * m^ 2 )/ s^s
what type of bond is Disulfide bonds
a covalent bond, between two sulfur atoms (–S–S–) formed by the coupling of two thiol (–SH) groups on Cysteine AA.
What amino acids are acidic? what is their net charge at physiological pH?
Aspartic acid (Asp, D) and glutamic acid (Glu, E) are the acidic AAs, will have neg negative charge at pH 7.4, Require decrease in pH to become neutral
separation by isoelectric point
protein will stop when it becomes neutral (pI)
What are the 4 assumptions made of “ideal gas”?
1) The gas particles have negligible volume.
2) IMF is negligible
3) The gas particles move randomly in agreement with Newton’s Laws of Motion.
4) Gas particles have perfect collisions with no lost energy
What is the ideal gas law?
PV=nRT
What is the function of rhodopsin?
allow for detection in low light conditions
Is a compound composed of mostly hydrogen and carbon hydrophobic or hydrophilic?
hydrophobic. Hydrophilic compounds are polar, charged side chains
What are the four charged amino acids?
(street) KRED- lysine, arginine, glutamate, aspartate
What are 2 types of linkages in glycogen structure?
alpha-1,4-glycosidic bond with branches joined by alpha-1,6-glycosidic bond.
What is UDP-glucose’s role in glycogen synthesis?
UDP glucose added to nonreducing end of glycogen molecule with release of UDP
What does a phosphatase enzyme do?
removes a phosphate group from a protein
In beta - decay, does the element go up or down on periodic table?
Electron emitted, neutron converted to proton and up 1 in periodic table
How will the rate of a catalyzed reaction be affected if the solid catalyst is finely ground before it is added to the reaction mixture?
The rate will be faster because a greater surface area of catalyst will be exposed.
Ohm’s law
V (volt)=I(Amperes) * R(ohm)
Electrical field equation and SI units
E= Fe/q = kQ/ r^2 (N/C or V/m)
What angle is considered half a wavelength, 180 degrees or 90 degrees?
180 degrees. Waves at 180 degrees of each other will produce destructive interference
What is the geometry of CH4?
tetrahedral, carbon bonded to 4 hydrogens with no lone pairs
What types of elements act as electron acceptors?
those with high electron affinity
Doppler effect equation
f’= (v +/- Vd)/ (v -/+ Vs). top sign forward, bottom sign away
doppler equation for frequency
Δf/f = -v/c
what travels faster– light or sound?
light
equation for buoyant force
Fb=-p g V. v = volume of displaced fluid. buoyant force opposes Fg= mg
how does the number of incident photons change at electrodes
only changes number of electrons released (proportionally) NOT energy
what does electron energy depend on
photon energy, work function, and potential difference
how does a charged particle move in an electric field?
a charged particle accelerates in an electric field
empirical formula
relative number of atoms each compound contains
how do you calculate the number of stereoisomers in a molecule
2^ n, where n is the number of chiral molecules in the compound
electric field lines move from what point to what point
postive to negative
rank in increasing size Sodium ion, Potassium ions, Chloride ion
Na+ < Cl - < K+
what are the charged amino acids
KRED- lys (+), arg (+), glutamate (-), aspartate (-)
what are the minimal variables needed for ultrasound via Doppler effect
speed of sound, frequency of sound waves emitted and observed.
Will liquids with a high vapor pressure evaporate more easily or less easily?
More easily, have weaker IMF (likely less H-bonding)
What is vapor pressure?
Vapor pressure is a measure of the pressure exerted by a gas above a liquid in a sealed container. Strong IMF in a liquid mean less evaporation and lower vapor pressure. Weaker IMF mean more evaporation and higher vapor pressure
What is principal quantum number?
describes the energy of an electron and the most probable distance of the electron from the nucleus
Describe basic structure of a fatty acid
a straight chain hydrocarbon tail and carboxylic acid group
If ligands are hydrophobic with anionic or electronegative features, what type of amino acids will be in active site?
hydrophobic and positively charged amino acids (hydrophobic- gly,val,ala,leu,ile and pos aa- arg, lys)
what is chirality
a figure that is not identical to its mirror image.
what is sublimation?
solid –> gas, can be used as separation technique of 1 subliminal material and 1 non subliminal material
ratio of the density of an object to the density of the fluid it is submersed in is equal to
ratio of the weight of the object in air to the difference of submersed weight and weight in air.
at pH 7, acidic groups on molecules will have what charge?
-1
What is the equation for energy of a photon?
E=hf (units– eV= 1.6*10^-19C)
What is the function of a protease?
Cleave peptide bonds
nano
10^−9
micro (µ)
10^-6
what is more polar 2-butanone or n-butanol?
butanol is more polar due to its ability to h-bond
When sitting up, why do you lean forward
to keep center of gravity in equilibrium, or else torque would make you fly back
What charge does a phosphate group have?
-1
What is a coordinate covalent bond?
Two electrons in the bond are donated by a single atom, as opposed to equal donation in traditional covalent bonding. Atom needs one lone pair. Examples)NH4, H3O
What type of bond is formed in Lewis acid–base interaction between a metal cation and an electron pair donor?
Coordinate covalent bond
What does the coordinate number refer to?
The number of ligands attached to the molecule
what is log .1
-1
Henderson-Hasselbach equation
pH= pKa + log (A-/HA)
what is the solubility product constant for substance AaBb?
Ksp= [A]^a [B] ^b
Bond length trend in PT
decreased down a row, increases down a group. C-H bonds are short bc hydrogen is so small
Enthalpy change of reaction bond formation
bonds broken - bonds formed
power is equal to
work per unit time
Increase in 10dB is proportional to
increase in intensity of sound by a factor of 10
What does a negative focal length mean for lens sytem?
it is a diverging lens, the image will always be virtual and upright. at distances outside of its focal length, image will be reduced.
What is the pH of the half equivalence point equal to in titration curve?
pKa
In titrations, what happens at the equivalence point?
when all of the acid is neutralized by the base (or all base neutralized by acid)
What is the equation for friction?
Ffriction= coefficient & F normal
normal force=mgcos (theta)
sin (0) and sin (180)
0
sin (90) =
1
cos (90)
0
cos(0) and cost (180)
1, -1
acceleration =
change velocity/ change in time
centripetal force equation
Fc= (m * v ^2)/r
Velocity at a point in time =
V= Vo + at
Displacement =
x= (Vo)t + (at^2)/2
finding velocity without time
v^2= Vo^2 + 2ax
Isothermal systems
constant temp, Q=w
isobaric system
constant pressure, Q=0, change in energy =-W
isovolumetric system
constant volume, no work done, change in energy equals change in heat
Force of magnetic field
q v B sin (theta)
Current =
Q/ change in time, measured in amperes
Resistance is =
(pL)/ A. INcreases with increasing length and increasing temp, decreases with increasing cross sectional area
Ohms law
V=IR
Capacitance
C=Q/v, in series 1/C= 1/C1 +1/C2, in parallel C=C1+C2. Opposite of resistance.
Parallel plate capacitor
Q= CV, V=Ed, C= eA/ d. Increase in area increases capacitance, increase in distance between plates decreases capacitance
What is the hendersen hasselbalch eq?
pH= pKa + log (B/A). use this to do a lot of things esp in titrations.
Conjugate acid/base pairs differ only with what?
presence/absence of H+
Why are pure solids and liquids left out of Equilibrium constant equation?
their presence is constant throughout the reaction. gases and substances are in equation
What is the critical point on a phase diagram?
The point at which the gas and liquid phases are indistinguishable from each other
What does an oxidoreductase enzyme do?
catalyzes transfer of elections from one molecule to another
What molecules form octahedral geometry?
AX6 system with no long pairs, in order to minimize the repulsive interactions of the bonding domain electrons
What is the structure of a porphyrin?
large ring molecule consisting of 4 pyrroles, which are smaller rings made from 4 carbons and 1 nitrogen.
How does DNA methylation alter transcription?
represses gene transcription
How does DNA acetylation alter transcription?
increases gene transcription (positively charged, counteracts negative charge of DNA)
What molecules form octahedral geometry?
AX6 system with no lone pairs, in order to minimize the repulsive interactions of the bonding domain electrons
What section of the periodic table are the alkali earth metals?
group 2 (Be, Mg, Ca…)
What section of the periodic table are the alkali metals?
group 1 (Li, Na…). lowest ionization energies
What section of the periodic table are the halogens?
Group 7 (F, Cl, Br, I…) highest EN, highest Ionization energies
What is a protease?
enzyme that catalyses breakdown of protein with water (it is a hydrolase)
Where do restriction enzymes cleave?
can only cleave at palandromes, known as restriction sites, and these are usually 4-6 base pair sequences
What is a phosphatide?
fatty acid esters of a glycerol phosphate with a nitrogenous base linked to a phosphate group
What is the difference between thermodynamic and kinetic products?
kinetic product is formed faster, but the thermodynamic product is more stable (lower energy)
What charges bind in anion exchange columns?
negatively charged peptides
What are the reactants in a strecker synthesis? what is the product?
an aldehyde + ammonium chloride and potassium cyanide. produces an amino acid.
What are the reactants in a gabriel synthesis?
potassium phatlamide, diethyl bromo, and alkyl halide. forms amino acid
What is the IR spec region for an N-H bond?
sharp, 3300
What is the IR spec region for a O-H bond?
broad, 3000-3300
What is the IR spec region for a C-O bond?
sharp, 1750
What is UV spec good for measuring?
molecules with double bonds (ie conjugated systems)
In NMR, what groups are to the left of the graph?
de-shielded groups (acids, aldehydes). useful in determining functional groups and connectivity of a compound. measured freq vs absorption
What does Mass spec measure?
molecular weight. M/z determines number of carbon (if m/z is 4.4/1.1, there are 4 carbons)
What is the difference between data interpolation and data extrapolation?
extrapolate is to further invesigate a known sequence beyond what is already known, interpolate is an estimation of value between two known values with date you already have (diluting the sample in this question would have brought it into your known range)
What is the difference between E and Z configuration
Z, the higher priority groups are the “zame zide”
E, the higher priority groups are opposite sides (ew)
What do Hertz measure (hz)?
how many intervals per second (a measure of frequency)
What is the structure of an amide?
carbonyl attached to nitrogen
What is the structure of an imine?
carbon double bounding to a nitrogen
What is the structure of an amine?
nitrogen with lone pair, mostly bound to carbon
What is fusion?
going from solid to a liquid
What is the triple point of a phase diagram?
the point where all 3 phases exist
What is the critical point of a diagram?
gas and liquid states exist in equilibrium
What charge are the beads of a anion exchange column?
positively charged. negative will bind and positive will elute out first
What are the charge of the beads in a cation exchange column?
negatively charged. positive will bind and negative will elute out first
What 3 things affect the melting point of dsDNA?
pH, length of DNA strand, ionic strength of solution
Which of the four base pairs has the greatest number of H bond acceptors?
cytosine
What is the equation for enzyme catalytic efficiency?
kcat/Km
What does increase in Km mean?
decrease affinity of enzyme for substrate
What does an SDS PAGE separate based off of?
denatures, separates based off protein size
What does a reducing SDS PAGE do>
the presence of a reducing agent breaks up disulfide bones, can break up proteins with disulfide bridges
What are alpha particles?
helium nuclei
What is the product of a carboyxlic acid and an alcohol with an acid catalyst and heat?
an ester
What is the rank of reactivity in carboxylic acid derivatives?
acyl halides are the most reactive > anhydrides > carboxylic acids and esters > amides are LEAST reactive
In polar protic solvents, which is more nucleophilic: I- or F-?
I-
In polar aprotic solvents, which is most nucleophilic: F- or I-?
F-
Why do diatomic molecules not appear on an IR spec graph?
there isno change in dipole moment
How does HOMO and LUMO change when number of conjugated systems increase?
the distance in energy decreases, smaller energies of light absorbed
What is the freezing point depression equation?
delta T = m * i * Kf
i= van hof factor
What is an overtone?
a harmonic ABOVE the fundamental frequency ( which is n=1)
Hydronium ion
H3O
Hydroxide ion
OH
What kind of curve will protein unfolding show?
sigmoidal
How many carbons in a terpene?
two isoprene units= 10 carbons
current flows…
opposite electrons
by what factor does sound change with distance?
if distance increases by 100, sound decreases be 100*100
As a wave travels from one medium to another, what changes- frequency or wavelength?
wavelength
