ACS BIOCHEMISTRY FIRST SEMESTER EXAM 2025-
2026 UPDATED QUESTIONS AND ANSWERS
Buffer Order and Henderson Hasselbach - Correct Answer - Water, Buffer, Salt, Base pH = pKa +
log(A/HA)
pKa decrease as temp increase so pH decrease
Ramachandran plots - Correct Answer - Φ = N-R ψ = C-R
optimal angle to prevent steric hinderance
Protein structure of a helix, B sheet, reverse turn - Correct Answer - a: LEMARKHQ B: VICYFTW
RT: PSDNG
how many amino acids in alpha turn helix - Correct Answer - 3.6
Super secondary structure - Correct Answer - helix turn helix
parallel vs. antiparallel - Correct Answer - parallel wedges face same way antiparallel face
opposite
Isoelectric point (pI) - Correct Answer - pH at which a particular molecule carries no net
electrical charge.
Protein Separation Techniques (ALL) - Correct Answer - Homogenization Salting Out
Affinity Chromatgraphy Ion Exchange
Size Exclusion/Gel Filtration H, S, A, I, SG
He said all individuals SinG
Protein Separation Techniques (S) - Correct Answer - Salting out different proteins precipitate
out at different salt concentrations
, Protein Separation Techniques (A) - Correct Answer - Affinity chromatography add a tag;
histidine binds; see how well there is an affinity for the group
Protein Separation Techniques (I) - Correct Answer - ion exchange separation based on charge;
+ proteins stick to - beads
Protein Separation Techniques (SG) - Correct Answer - Size Exclusion/Gel Filtration separation
based on size
Cuts (protein separation techniques) - Correct Answer - cut out what dont need/isnt protein (use
40% concen. then keep liquid; if use 60% concen. then keep pellet)
Dialysis - Correct Answer - protein separation based on bad with pores
Moles in bag + moles in buffer
Divide moles by total volume - new concentration
Electrophoresis - Correct Answer - gels - move by size with electric current
Isoelectric focusing - purely pH
SDS page
pH separation is by pI and charge in 2d
Protein sequencing (who cuts after what) - Correct Answer - Cyanogen bromide = methionine
trypsin = K, and R
chymotrypsin = F, M, L, W, Y
IP - Correct Answer - Immunoprecipitation with proteins
add antibodies specific to protein of interest to lysed cells
add antibody binding protein on beads
centrifuge and protein is on bead with antibodies
gel elect
CO-IP - Correct Answer - observe protein protein interaction
Messelson Stalh - Correct Answer - RATSHIT.
Western Blotting - Correct Answer - run gel - transfer to sheet - stained with radioactive
antibody
- autoradiogram - exposed antibody
ELISA - indirect and sandwich - Correct Answer - Enzyme linked immunosorbant assay
indirect - antigen coated well - bind persons antibody - bind antigen with enzyme - bind
substrate = rate of color
Sandwich - antibody coated well - bind person antigen - bind 2nd antibody with enzyme - bind
substrate = rate of color
Mass spec - Correct Answer - identify proteins by size
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