Exam 1 Flashcards
L-Threonine and D-Threonine (he puts the structures) are what type of stereoisomers..
Enantiomers..
What is the designation of stereoisomers that is based on observed rotation of plane-polarized light..
d and l (take care it is small letters)
At dynamic steady state living cells are..
cells have constant amount of substance (constancy of concentration) , the amount of synthesized substance is equal to the degraded ones.
The hydrolysis (breakdown) of peptide bond is..
exergonic and slow
Which of the following is true regarding Albuterol..
Commercially available albuterol is a racemic mixture of the two isomers.
(Note: R-albuterol is more effective than S,, so if we prepare only R-albuterol product we may need to reduce the dose with the same effect of the current commercially available product.)
L-threonine and D-allo threonine are
Diastereomers
Enthalpy (ΔH)= +29.7
so the reaction is → Endothermic
When the gas dissolves in a buffer, the Entropy (ΔS)
Decreases
In ice cold bags, we have urea and water. When they mix, the bags will be cold.
What would happen to the enthalpy and the entropy?
Enthalpy is changing positively (ΔH>0) & Entropy is changing positively (ΔS>0)
Which group is not likely to form H-bond with water?
Phenyl
What is true of hypertonic solutions?
Higher osmolarity than the cell
Cells put in a hypertonic solution will shrink
Carbonic acid (H2CO3) is diprotic. Pka’s of 3.77 and 10.2. What form is dominant at pH 7.5? and I think also at 3?
(H2CO3 ——> HCO3 ——-> CO3)
bicarbonate Pka=6.1, he want [CO2], [HCO3]
PH= 7.4 in our body
considering acetate/acidic acid buffer, when pH = pKa (4.7) and you add HCl
pH change will be less than when the same amount of HCl is added @ pH of 7
(better buffering capacity when pH is equal to pKa, buffers don’t want the pH to change)
the next one was a math problem but you have to remember…
pH= pKa + log (base/acid)
he give to PH= 5.5 , Pka=4.5
what is acid to base ratio ?
10/1
if the pH is 4.5 and Pka is 5.5 what is the ration of acid to base?
(Henderson Hasselbalch: pH = pKa + log([Base]/[Acid])
aspirin has Pka 3.5 and it’s absorbed when it is un-charged. what is the best pH for aspirin to be absorbed?
pH< 3.5 (acidic)
if a molecule is in pH less than its PI then the net charge is..
positive
which AA has a guanidinum side chain?
Arginine
which molecule has a highest light absorbance?
lys-tyr-trp
which molecule has the most ionizable groups?
(lys-asp-glu… not sure exactly so just memorize +ve & -ve charged a.a.)
How much will be the charge on Histidine with given Pk1 & Pk2 at PH = 7.4?
The answer will be 0
How much will be the charge on Tyrosine with given Pk1 & Pk2 at PH = 11?
The answer will be -2
Dissociation of Aspartate at different PH (24-26): - At which PH there will be an equal amount of forms 1 & 2?
It will be at PH = Pk1 = 1.8
At which PH there will be more of form 3 ( charge = -1)?
It will be at PH = 0.5 ( Pkr + Pk2 ) = 7
The pI for this molecule will be ?
The answer will be at PH = 0.5 ( Pk1+ Pkr )
Separation of a protein with different pI than the others?
The answer is by using the Ion-exchange chromatography.
Separation of a protein with different Molecular Weight than the others?
SDS-PAGE (Electrophoresis) (the slowest mover on the page)
Separation using Combining 2-dimensional (electrophoresis IEF and SDS-PAGE):
The answer were 1) Isoelectric focusing (charge-based) & 2) SDS-PAGE (size-based)
Questions about this peptide (Alanine-Histidine-Tryptophan-Glutamine)
What’s the net charge at PH 7? Answer +1
Questions about this peptide (Alanine-Histidine-Tryptophan-Glutamine)
What’s the net charge at PH 14? Answer -1
It was about Enzyme activity or specificity
To answer the question you only have to subtract the two numbers given for each enzyme
In mixture of five proteins, which one will elute Second to size exclusion (gel filtration) chromatography:
RNA Polymerase 150,000 Mt (the first one is the bigger in size which is 300,00 Mt)
Which Amino Acids act as natural Buffer in living cells?
Histidine
In the Peptide Ala-Glu-Lys-Ala-Leu which one is true:
2 free Amino group
Which structure has 2 Chiral Centers
Look at the structure to find out
Choose from the structures: Glutamine
…
Choose from the structures: Lysine
…
Choose from the structures: Serine in form A and Tyrosine in form B (question was different in form B)
…
