Exam 1

Question 1

L-Threonine and D-Threonine (he puts the structures) are what type of stereoisomers..

Answer 1

Enantiomers..

Question 2

What is the designation of stereoisomers that is based on observed rotation of plane-polarized light..

Answer 2

d and l (take care it is small letters)

Question 3

At dynamic steady state living cells are..

Answer 3

cells have constant amount of substance (constancy of concentration) , the amount of synthesized substance is equal to the degraded ones.

Question 4

The hydrolysis (breakdown) of peptide bond is..

Answer 4

exergonic and slow

Question 5

Which of the following is true regarding Albuterol..

Answer 5

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.)

Question 6

L-threonine and D-allo threonine are

Answer 6

Diastereomers

Question 7

Enthalpy (ΔH)= +29.7

Answer 7

so the reaction is → Endothermic

Question 8

When the gas dissolves in a buffer, the Entropy (ΔS)

Answer 8

Decreases

Question 9

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?

Answer 9

Enthalpy is changing positively (ΔH>0) & Entropy is changing positively (ΔS>0)

Question 10

Which group is not likely to form H-bond with water?

Answer 10

Phenyl

Question 11

What is true of hypertonic solutions?

Answer 11

Higher osmolarity than the cell

Cells put in a hypertonic solution will shrink

Question 12

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?

Answer 12

(H2CO3 ——> HCO3 ——-> CO3)

Question 13

bicarbonate Pka=6.1, he want [CO2], [HCO3]

Answer 13

PH= 7.4 in our body

Question 14

considering acetate/acidic acid buffer, when pH = pKa (4.7) and you add HCl

Answer 14

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)

Question 15

the next one was a math problem but you have to remember…

Answer 15

pH= pKa + log (base/acid)
he give to PH= 5.5 , Pka=4.5
what is acid to base ratio ?
10/1

Question 16

if the pH is 4.5 and Pka is 5.5 what is the ration of acid to base?

Answer 16

(Henderson Hasselbalch: pH = pKa + log([Base]/[Acid])

Question 17

aspirin has Pka 3.5 and it’s absorbed when it is un-charged. what is the best pH for aspirin to be absorbed?

Answer 17

pH< 3.5 (acidic)

Question 18

if a molecule is in pH less than its PI then the net charge is..

Answer 18

positive

Question 19

which AA has a guanidinum side chain?

Answer 19

Arginine

Question 20

which molecule has a highest light absorbance?

Answer 20

lys-tyr-trp

Question 21

which molecule has the most ionizable groups?

Answer 21

(lys-asp-glu… not sure exactly so just memorize +ve & -ve charged a.a.)

Question 22

How much will be the charge on Histidine with given Pk1 & Pk2 at PH = 7.4?

Answer 22

The answer will be 0

Question 23

How much will be the charge on Tyrosine with given Pk1 & Pk2 at PH = 11?

Answer 23

The answer will be -2

Question 24

Dissociation of Aspartate at different PH (24-26): - At which PH there will be an equal amount of forms 1 & 2?

Answer 24

It will be at PH = Pk1 = 1.8

Question 25

At which PH there will be more of form 3 ( charge = -1)?

Answer 25

It will be at PH = 0.5 ( Pkr + Pk2 ) = 7

Question 26

The pI for this molecule will be ?

Answer 26

The answer will be at PH = 0.5 ( Pk1+ Pkr )

Question 27

Separation of a protein with different pI than the others?

Answer 27

The answer is by using the Ion-exchange chromatography.

Question 28

Separation of a protein with different Molecular Weight than the others?

Answer 28

SDS-PAGE (Electrophoresis) (the slowest mover on the page)

Question 29

Separation using Combining 2-dimensional (electrophoresis IEF and SDS-PAGE):

Answer 29

The answer were 1) Isoelectric focusing (charge-based) & 2) SDS-PAGE (size-based)

Question 30

Questions about this peptide (Alanine-Histidine-Tryptophan-Glutamine)

Answer 30

What’s the net charge at PH 7? Answer +1

Question 31

Questions about this peptide (Alanine-Histidine-Tryptophan-Glutamine)

Answer 31

What’s the net charge at PH 14? Answer -1

Question 32

It was about Enzyme activity or specificity

Answer 32

To answer the question you only have to subtract the two numbers given for each enzyme

Question 33

In mixture of five proteins, which one will elute Second to size exclusion (gel filtration) chromatography:

Answer 33

RNA Polymerase 150,000 Mt (the first one is the bigger in size which is 300,00 Mt)

Question 34

Which Amino Acids act as natural Buffer in living cells?

Answer 34

Histidine

Question 35

In the Peptide Ala-Glu-Lys-Ala-Leu which one is true:

Answer 35

2 free Amino group

Question 36

Which structure has 2 Chiral Centers

Answer 36

Look at the structure to find out

Question 37

Choose from the structures: Glutamine

Answer 37

…

Question 38

Choose from the structures: Lysine

Answer 38

…

Question 39

Choose from the structures: Serine in form A and Tyrosine in form B (question was different in form B)

Answer 39

…