Chem/Phys Questions Flashcards
how do beta and gamma radiation differ?
beta radiation aka electrons will be deflected in a magnetic field while gamma radiation aka photons will not
how do BP and BFR (blood flow rate) differ in pulmonary and systemic circulation?
BP is higher in systemic circulation - pulmonary circuit is shorter so has less resistance
BFR will be the same - pulmonary and systemic circulations are connected in series so flow rate is equal (analogous to current)
resistance and area
R = (rhoL)/A
shorter or wider will mean less resistance
what type of charged molecule will migrate towards the cathode?
cations (positively charged)
cathode behaves negative
acid strength
increased by having the most electronegative group (eg fluoroacetic acid)
stronger acid = more stable conjugate base
mutarotation
cyclic hemiacetal formations of monosaccharides can open and then re-cyclize, with equal amounts of alpha and beta anomers
infrared spectroscopy
sharp peak at 1700 means carbonyl group
O-H stretching frequency is 3200-3500
intensity is ____ proportional to area
inversely proportional to area
sound travels fastest in a ____
solid
furanose and pyranose
a furanose is 5 membered (fructofuranose)
a pyranose is 6 membered (glucopyranose)
which form of glucose can undergo oxidation?
linear form of glucose
not hemiacetal form!
chymotrypsin
preferentially cleaves peptide bonds next to large hydrophobic amino acids, preferentially aromatic amino acids
number of stereoisomers
2^n where n is the number of chiral centers
electric field lines
go from positive to negative charges
eg an axon is negatively charged and the extracellular solution has a zero net potential, so the field lines point inward
current depends on
Ohm’s Law V=IR
to determine resistance: use resistance per unit length and length
squalene
precursor to steroids
cholesterol, testosterone, cortisol, etc.
what is the concentration of Cl- ions in a 0.1 M solution of CaCl2?
0.2M
produces twice as many Cl- ions as Ca2+ ions when it dissolves
sucrose
does not possess a hemiacetal functional group and will not undergo mutarotation or be oxidized
saccharides undergo mutarotation if they are capable of ring-opening which occurs at the hemiacetal group (these are reducing sugars because they can be oxidized by Ag+)
Lineweaver-Burk plot
y-intercept: 1/Vmax
x-intercept: 1/Km
how does a barometer work?
air pressure outside is higher than air pressure inside
reaches equilibrium by building pressure inside through raising the liquid level so that air pressure + liquid pressure inside is equal to air pressure outside
1 m^3 equals
10^6 cm^3
the Doppler effect
relates the frequency of the ultrasound wave as detected by a moving detector to the frequency of the wave when the source is stationary, the speed of the source, and the speed of the detector
ultrasound requires speed of the sound and frequencies of sound waves emitted and observed
heat equation
q = mCdT C = specific heat m = mass dT = change in temperature
how can a single stereoisomer be formed?
neither reactant is chiral –> the enzyme is chiral
diverging lens
concave lens
used in myopia to focus light on the retina
converging lens is convex
calculate the density of a human body from its weight in air and its weight while submersed in water
density is proportional to:
Wair/(Wair-Ww)
Archimedes’ principle: ratio of the density of an object to the density of the fluid it is submersed in = ratio of the weight of the object in air to the difference of submersed weight and weight in air
amino acids that contribute to stabilization of ADP binding
histidine and arginine (or lysine)
positively charged side chains have favorable ionic interactions with the negatively charged phosphates of ADP
NADH to NAD+
oxidation
NAD+ is reduced to NADH
frequency of a photon
E = hf where h is Planck’s constant (6.62 x 10^-34)
power, work, time
P = W/t W = Pt
half-reaction for oxidation of NADH
NADH –> NAD+ + H+ + 2e-
balance hydrogens and then balance charge with e-
why do nickel ions form a green solution?
nickel has a partially filled d orbital
lower energy d orbital electrons will absorb visible light to move into higher energy orbitals
Hendersson Hasselbach equation
pH = pKa + log (conj base)/(conj acid)
if something dissociates at pka 6 and experimental pH is 8, ratio is 100:1 or 10^2
what increases the boiling point of a liquid?
hydrogen bonding
eg glycerine has 3 OH groups to participate in hydrogen bonding vs isopropyl alcohol only has 1 OH group, so glycerine will have a significantly higher boiling point
atomic radius trends
increase down a period
decrease down a row - this is because the effective nuclear charge increases, holding electrons closer to the nucleus
why does glycine form a dipolar ion in aqueous solution?
high dipole moment
zwitterion means highly electron withdrawing and electron drawing substituents which add to polarity
phase difference
half a wave phase difference = 180 degrees = destructive interference
full wave phase difference = 360 degrees = constructive interference
frequency and period
T = 1/f
Hertz (frequency) to s (period)
100 Hz = 1/100 s-1 = 0.01 seconds
200 Hz = 1/200 s-1 = 0.005 seconds
amide group
bond that forms between amino acids in a peptide
amine group + carboxyl group
first peak in gas chromatography
molecule with lowest molecular weight and weakest intramolecular bonds –> migrates the fastest
inversion of stereochemistry
incoming nucleophile displaces the leaving group from the opposite side of a reacting center during an SN2 reaction
speed and index of refraction
index of refraction in a medium = speed of light in vacuum/speed of light in the medium
work power time
W = P t
hybridization of central atom of octahedral compound
d2sp3
has 6 sigma bonds and no lone pairs
why do we have a variety of opsins?
to enable the detection of different colors
how can you tell a molecule is hydrophobic?
primarily made up of Cs and Hs
binding site will also be hydrophobic
chain linkage of glycogen
alpha-1,4-glycosidic bond
branching in glycogen is alpha-1,6
dissociation of acid in water
negative charge eg HPO42- will make dissociation weaker/less likely
electrochemistry: what makes a reaction spontaneous?
when E>0, the reaction is spontaneous (opposite of delta g)
kcat
when enzyme is saturated with substrate, kcat = Vmax/enzyme concentration
absorption of UV light by organic molecules results in
excitation of bound electrons
stationary phase of column chromatography is silica gel
silica gel is polar
most nonpolar compounds will elute first, most polar will elute last
sort by polarity: alcohol ketone carboxylic acid alkane
most to least polar: carboxylic acid alcohol ketone alkane
charged amino acids at pH 7
positive - lysine (K), arginine (R), histidine at lower pH
negative - glutamic acid (E), aspartic acid (D)
Venturi effect
air enters a mask because the static pressure of the air is larger than the static pressure of the oxygen in flow
why do G-C base pairs have a higher melting point than A-T pairs?
increased pi bond stacking strength
what property of a substance is best used to estimate its vapor pressure?
boiling point
storage lipids
triglycerides/triacylglycerols
3 fatty acids attached to a single glycerol
in an electrochemical cell, where do oxidation and reduction occur?
oxidation always occurs at the anode
reduction always occurs at the cathode
coordinate covalent bond
Lewis acid-base interaction between a metal cation and an electron pair donor
eg the bond between Cu2+ and nitrogen atoms of ammonia in (Cu(NH3)4)2+
coordination number
number of molecules that bind to a central cation
what forms the exterior of the double helix?
sugar-phosphate backbone
highest bond energy =
shortest bond length
C-H is short bc of H’s small atomic radius
work done stretching
W = 1/2kx^2
ratio of 20dB to 40dB
100
decimal log of the ratio of their intensities is 2 –> ratio is 100
negative focal length of a lens
diverging lens (concave) forms virtual, reduced images
energy conversions in a battery-powered resistive circuit
chemical energy to electrical energy to thermal energy
energy is dissipated as heat from the resistor
protein secondary structure is characterized by the pattern of hydrogen bonds between
backbone amide protons and carbonyl oxygens
side chain protons/oxygens are not involved
most likely to undergo SN1 reaction
tertiary carbocation is most stable
kinetic energy of a photon
energy of the photon Hf - work function
energy power time
E = P t
for concentration questions
remember to account for amount of solution actually used
eg 0.1 mM of 800 g/mol MW would be be 80 mg in 1 L, but in 1 mL the answer is divided by 1000
compound 1 elements are mixed and do not combine but compound 2 elements do combine when mixed, what does this tell us about kinetic/thermodynamic control?
compound 1 is kinetically controlled - elements do not mix spontaneously so they do not convert to most thermodynamically stable forms
compound 2 is thermodynamically controlled - elements do mix by converting to most thermodynamically stable forms
mixing suspensions
results in average concentration
eg mixing 0.1 and 0.2 concentration will give a single peak at 0.15
note for electron configurations
if a configuration looks like 4s23d5 it actually loses the 4s2 electrons first to leave 3d7
fill in 3d orbitals before 4s
power force velocity
power = force x velocity
experimental data which indicates thermodynamic stability
heat of combustion
Kb
Kw/Ka for conjugate acid
Kb > Ka indicates more basic, Ka > Kb indicates more acidic
Kw = (Ka)(Kb)
FAD
cofactor oxidant
FADH and NADH are reducing agents
byproduct of peptide bond formation
H20 - 18 amu
heme component
porphyrin
pyrrole ring - 5 membered ring including nitrogen
resistivity
inverse of conductivity and vice versa
property of a wave unaffected by medium
frequency
