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Biochem ACS Review Questions and Answers
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Exam of 6 pages for the course Biochemistry ACS at Biochemistry ACS (Biochem ACS Review)
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Biochem ACS ReviewWhat amino acids have nonpolar, aliphatic R groups? - answerGlycine, Alanine, Proline,
Valine, Leucine, Isoleucine, Methionine
What amino acids have polar, uncharged R groups? - answerSerine, Threonine,
Cysteine, Asparagine, and Glutamine
What amino acids have aromatic R groups? - answerPhenylalanine, Tyrosine, and
Tryptophan
What amino acids have negatively charged R groups? - answerAspartate and
Glutamate
What amino acids have positively charged R groups? - answerLysine, Arginine, and
Histidine
What is isoelectric focusing? - answerProteins are electrophoresed in a pH gradient gel.
Each protein will move in the gel as long as the protein contains a charge
What does SDS do? - answerIt binds to proteins and denatures it. All proteins have
same mass/ charge ratio
How do you determine the Amino Terminus? - answer1. Make a derivative of the N-
terminus with a marker molecule
2. Hydrolyze the peptide
3. N-terminal AA is identified by chromatography- modified amino acid will elute
differently than unmodified AA
What molecule does Edman Degradation use? - answerPhenyl Isothiocyanate (PTH)
What does Edman Degradation do? - answerIt removes one amino acid at a time. The
limit is 50 amino acids. After 50 amino acids, the polypeptide must be hydrolyzed into
smaller fractions
Where does Cyanogen Bromide cleave? - answerCleaves only on the caryboxyl side of
Methionine residues
Where does Trypsin cleave? - answerTrypsin cleaves on the carboxyl side of positive
residues such as Arginine and Lysine
What happens in Disulfide Position? - answerIt is a diagonal electrophoresis.
, The peptides are cleaved without destroying the disulfide bonds and then exposed to
performic acid vapors.
The performic acid vapors convert any S-X bond to a SO3-.
These fragments will be off the diagonal
In Peptide Synthesis, what is the protecting group? - answerFmoc
What is the group that activates amino acid 2? - answerDCC- Dicyclohexylcarbodiimide
What acts as the nucleophile in Peptide Synthesis? - answerAmino acid 1 that is
connected to the polystyrene bead.
What causes the polystyrene bead to disconnect from amino acid 1? - answerHF
In what order does peptide synthesis, synthesize amino acids? - answerCarboxy end to
the amine end
In what order does the body synthesize amino acids? - answerAmino terminus to
carboxy terminus
What are the hydrogen bonds in Alpha Helix? - answerThe carboxyl group is hydrogen
bonded with the Hydrogen on the Nitrogen 4 residues away. Alpha helix is clockwise, or
right handed
Which Beta Pleated sheet is more stable, parallel or antiparallel? - answerAntiparallel,
because there is a direct overlap of electrons which creates more stability
What does B-mercaptoethanol do? - answerIt breaks disulfide bonds
What does Urea do? - answerIt interrupts hydrogen bonds
What is Levinthal's Paradox? - answerIt is the difference between the calculated time for
a protein to fold and the real time it take for a protein to fold.
The discrepancy in time is answered by what? - answerProgressive stabilization
What is Progressive stabilization? - answerIt is the stabilization of intermediates that
resemble parts of the final folded state
What is the molten globule state? - answerIt is the state between random coil and native
state. It contains much secondary structure.
How is the molten globule formed? - answerIt is formed by hydrophobic collapse.
Hydrophobic residues are sequestered toward the inside of a protein
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