Bioc 2580 Midterm UPDATED ACTUAL
Exam Questions and CORRECT Answers
very non-polar side chains - CORRECT ANSWER - ala, val, leu, ile, met, phe
- side chains are dominated by non-polar and hydrophobic hydrocarbons
moderately non-polar - CORRECT ANSWER - gly, cys, pro, tyr, trp
-gly: single H, not enough to be very non-polar
-cys: slightly polar SH
-pro: side chain links to N and alpha C, polar non moderates non-polar hydrocarbon
-tyr & trp: single polar group that partly offsets very non-polar benzene
polar uncharged - CORRECT ANSWER - ser, thr, asn, gln
-ser & thr: side chains with OH
asn & gln: polar amide groups
-don't hain or lose H+ in aqueous solution at pH 7, so they're uncharged
-good H bond acceptors
very polar positively charged - CORRECT ANSWER - His, lys and arg
- contain weak bases that gain H+
-charge makes them very polar, overriding non-polar hydrocarbons
very polar negatively charged - CORRECT ANSWER - -have carboxylic acid groups that
lose H+
henderson-hasselbalch equation - CORRECT ANSWER - pH=pKa+log [deprotonated] /
[protonated]
, deprotonated - CORRECT ANSWER - pH is one unit higher than pKa
protonated - CORRECT ANSWER - pH is one unit below pKa
partition chromatography - CORRECT ANSWER - -stationary phase that hydrogen bonds
to polar AAs
-mobile phase that flows past the particles and is non-polar
-polar AA spend more time hydrogen bonded and move slowly
-nonpolar AA spend more time in solvent and move almost as fast as solvent
thin layer chromatography - CORRECT ANSWER - -silica gel is spread in a thin layer on
a plastic sheet, this is the polar stationary phase
-samples are applied to lower edge and placed in solvent
-solvent soaks up sheet and non-polar AA move with the solvent
-highest point reached by solvent is the solvent front
-relative mobility: RF=XB (distance travelled by sample) / XF(distance travelled by solvent
-nonpolar AA have high RF (mobile)
-polar AA have low RF (stationary)
column chromatography - CORRECT ANSWER - -sample is added
-buffer is added, carrying sample out
-contents of collection is analysed and plotted
-volume of buffer needed to move a component through the column is the elution volume
-highest elution volume=took longest to come out (most polar, bonded to gel)
ninhydrin - CORRECT ANSWER - -detects AA
-react with primary and secondary amines
-gives a purple colour
Exam Questions and CORRECT Answers
very non-polar side chains - CORRECT ANSWER - ala, val, leu, ile, met, phe
- side chains are dominated by non-polar and hydrophobic hydrocarbons
moderately non-polar - CORRECT ANSWER - gly, cys, pro, tyr, trp
-gly: single H, not enough to be very non-polar
-cys: slightly polar SH
-pro: side chain links to N and alpha C, polar non moderates non-polar hydrocarbon
-tyr & trp: single polar group that partly offsets very non-polar benzene
polar uncharged - CORRECT ANSWER - ser, thr, asn, gln
-ser & thr: side chains with OH
asn & gln: polar amide groups
-don't hain or lose H+ in aqueous solution at pH 7, so they're uncharged
-good H bond acceptors
very polar positively charged - CORRECT ANSWER - His, lys and arg
- contain weak bases that gain H+
-charge makes them very polar, overriding non-polar hydrocarbons
very polar negatively charged - CORRECT ANSWER - -have carboxylic acid groups that
lose H+
henderson-hasselbalch equation - CORRECT ANSWER - pH=pKa+log [deprotonated] /
[protonated]
, deprotonated - CORRECT ANSWER - pH is one unit higher than pKa
protonated - CORRECT ANSWER - pH is one unit below pKa
partition chromatography - CORRECT ANSWER - -stationary phase that hydrogen bonds
to polar AAs
-mobile phase that flows past the particles and is non-polar
-polar AA spend more time hydrogen bonded and move slowly
-nonpolar AA spend more time in solvent and move almost as fast as solvent
thin layer chromatography - CORRECT ANSWER - -silica gel is spread in a thin layer on
a plastic sheet, this is the polar stationary phase
-samples are applied to lower edge and placed in solvent
-solvent soaks up sheet and non-polar AA move with the solvent
-highest point reached by solvent is the solvent front
-relative mobility: RF=XB (distance travelled by sample) / XF(distance travelled by solvent
-nonpolar AA have high RF (mobile)
-polar AA have low RF (stationary)
column chromatography - CORRECT ANSWER - -sample is added
-buffer is added, carrying sample out
-contents of collection is analysed and plotted
-volume of buffer needed to move a component through the column is the elution volume
-highest elution volume=took longest to come out (most polar, bonded to gel)
ninhydrin - CORRECT ANSWER - -detects AA
-react with primary and secondary amines
-gives a purple colour
