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BCH 4053 Final Exam questions correctly answered already passed
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BCH 4053 Final Exam questions correctly answered already passed
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BCH 4053 Final ExamLeucine - Leu, L - correct answer ✔✔Non-polar
Proline - Pro, P - correct answer ✔✔Non-polar - often found in b-pleated sheets (Pro kinks)
Alanine - Ala, A - correct answer ✔✔Non-polar
Valine - Val, V - correct answer ✔✔Non-polar
Glycine - Gly, G - correct answer ✔✔Non-polar - not chiral
Serine - Ser, S - correct answer ✔✔Polar, pKa: 13
Asparagine - Asn, N - correct answer ✔✔Polar
Glutamine - Gln, Q - correct answer ✔✔Polar
Aspartic Acid - Asp, D - correct answer ✔✔Polar, acidic, pka: 3.8
Glutamic Acid - Glu, E - correct answer ✔✔Polar, Acidic, pKa: 4.3
Methionine - Met, M - correct answer ✔✔Non-polar
Tryptophan - Trp, W - correct answer ✔✔Nonpolar, Aromatic
Phenylalanine - Phe, F - correct answer ✔✔Nonpolar, Aromatic
,Isoleucine - Ile, I - correct answer ✔✔Nonpolar
Threonine - Thr, T - correct answer ✔✔Polar, uncharged, pKa: ~13
Cysteine - Cys, C - correct answer ✔✔Polar, uncharged (can form disulfide bridge) pKa:8.3
Tyrosine - Tyr, Y - correct answer ✔✔Aromatic, Polar, uncharged, pKa: 10.1
Histidine - His, H - correct answer ✔✔Polar, pKa: 6
Lysine - Lys, K - correct answer ✔✔Basic, pKa: 10.5
Arginine - Arg, R - correct answer ✔✔Basic, pKa: 12.5
All natural AAs are D or L - correct answer ✔✔L
All AAs are (R/S) except - correct answer ✔✔S; Cysteine is R because of its large R-group
What is the pKa of a COO- group in a peptide? What is the pKa of a free AA? - correct answer ✔✔Peptide
COO-: 3
Free AA COO-:2
What is the pKa of a NH3 group in a peptide? What is the pKa of an NH3 group in a free AA? - correct
answer ✔✔Peptide NH3: 8
Free AA NH3: 9.5
What does the pI (isoelectric point) mean? Is the protein/AA most or least soluble at this pH? - correct
answer ✔✔negative charges = positive charges
neutral net charge
, it is least soluble
What are the aromatic AAs? what wavelength (nm) do they absorb at - correct answer ✔✔Phe, Tyr, Trp
~280 nm
What is the geometry of a peptide bond? - correct answer ✔✔trans configuration, double bond
character, six atoms of the peptide are coplanar; resonance stabilizes the peptide
Primary structure - correct answer ✔✔the peptide bonds (covalent) linking each AA together - sequence
Secondary structure - correct answer ✔✔The interactions of the peptide backbone (h-bonding); a-
helices and b-pleated sheets
Tertiary structure - correct answer ✔✔Interactions between R-groups of AAs; H-bonding, hydrophobic
effect, salt bridge, disulfide link (covalent)
Quartnary structure - correct answer ✔✔Assembly to subunits - not all proteins have this
simple proteins - correct answer ✔✔proteins containing only AAs
Prosthetic group - correct answer ✔✔Non AA constituents of proteins - tightly bound
Apoprotein - correct answer ✔✔Protein minus prosthetic group (inactive)
Haloenzyme - correct answer ✔✔Protein plus prosthetic group (active)
Cation exchange - correct answer ✔✔negatively charged resin, you want the positively charged proteins.
start with a low pH (pH below all the pkas), slowly increase the pH.
positively charged AA should elute last, and are eluted using salt
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