Chem/Phys Flashcards
Compare Accuracy vs. Reliability
Accuracy is a measure of how close a value is to the true or target value.
Reliability is a measure of the consistency with which a measuring device reports the same value for the same measured event. So it is how well a measurement can be repeated.
It is possible to be highly reliable but inaccurate if you consistently measure the same value but it is not the true value.
Equation for capacitance:
Capacitance is the amount of charge stored per volt:
C = Q/V
Give a reason why bacteria might be successful at evading host system responses.
One way that organisms fight foreign invaders is through restriction endonucleases that recognize ‘non-self’ DNA sequences. These endonucleases have very specific restriction sites (it would be very dangerous to have endonucleases without specific sites, since they could cleave any DNA).
So if a bacteria could disrupt restriction endonucleases that target non-self DNA molecules to degrade them, they would be successful in invading the host without detection.
Henderson-Hasselbalch equation
pH = pKa + log([HCO3-]/[H2CO3])
pKa = -logKa
When the concentrations of of the conjugate acid and its conjugate base are equal ([HCO3-] = [H2CO3]) pH = pKa
How does carbonic anhydrase effect blood pH and what reaction is it named after?
Enzymes speed up reactions, but do not change the equilibrium concentrations of reactants and products. Therefore, the presence or absence of carbonic anhydrase will not have an impact on blood pH, it will only impact the rate at which the reaction proceeds.
Carbonic anhydrase catalyzes the aqueous equilibrium between carbonic acid, water and carbon dioxide. The “anhydrase” specifically refers to the removal of a water molecule which refers to the rxn going to the left of carbonic acid being hydrolyzed into CO2 and H2O.
Which part of the bicarbonate buffer reaction involves blood homeostasis?
H2CO3 (aq) + H2O (l) ⇌ H3O+ + HCO3– (aq)
This reaction resists dramatic pH shifts in solutions titrated with acid, it is responsible for maintaining blood pH.
Alveolar P(CO2) must be greater than ambient P(CO2) because CO2 diffuses from the blood into the alveoli at the lungs.
Why is the diol equilibrium more favorable in the formation of cyclic acetals?
The formation of cyclic acetals is more thermodynamically favorable than the formation of acyclic acetals due to a more favorable change in ENTROPY.
Kinetics on the other hand, would describe the rate of the reaction not the equilibrium (Keq).
A positive change in enthalpy would be thermodynamically unfavorable.
Using this RNA as a template, the enzyme reverse transcriptase would produce what nucleotide polymer?
5’ GGAUCCUGAAC 3’
5’ GTTCAGGATCC 3’
To answer this question, one must remember that reverse transcriptase is an RNA-dependent DNA polymerase and, as such, it will generate a DNA molecule. This means that the answer must contain “T” instead of “U”. It must also be complimentary to the genomic DNA given in the question.
First order rate of reaction graph
A graph of ln[A] vs. time is expected to be linear
How do you find the total pressure of a gas that is collected over water?
P of gas = total pressure - vapor pressure
For any situation where gas pressure is being measure over a volatile liquid vapor pressure must be considered in the pressure of the gas.
Note: 1 atm = 760 torr.
How is priority ranked in a chiral carbon?
The highest priority is given to the atom with the highest atomic number.
Ionization energy
Ionization energy is the amount of energy required to completely remove one valence electron from an isolated atom in the gaseous sate.
The periodic table trend for IE increases as one moves up and to the right.
N and O are the exception to these trends, however, due to electron repulsion from oxygen’s additional electron in the already half-filled 2p orbital. Therefore, N > O.
What are mesophiles and how do high temperatures effect their proteins?
Mesophiles are organisms that live in environments with moderate temperatures. As such, they have not adapted to high temperatures.
Temperatures above the melting point of a protein will cause denaturation, which will melt the hydrogen bonds that hold secondary and tertiary structures together.
Primary structure however, is created by peptide bonds, which are covalent and will not be broken by increased temperatures within a reasonable range. Disulfide bonds are also covalent so the same principle applies to them.
Complete β-oxidation of a 20 carbon fatty acid will produce how many acetyl-CoA and succinyl-CoA molecules, respectively?
10 and 0
For each round of β-oxidation, an acetyl CoA is generated and the fatty acid is shortened by two carbons. The final round generates two acetyl CoA’s. To calculate how many acetyl CoA’s will be generated, simply divide the number of carbons by two.
If the fatty acid had an odd-numbered chain, the final step would involve cleaving a 5-carbon chain into an acteyl CoA (2 carbons) and a succinyl CoA (3 carbons).
Ex: a 21 carbon FA would produce 9 and 1.
If temperature is gradually increased what will happen to the rate of reaction?
According to the Arrhenius equation, and kinetic principles generally, the reaction rate should increase with any temperature increase.
Arrhenius equation = k = Ae^(-Ea/RT)
