BMB401 Exam I Practice ExamID Page SA Key Show all your work for questions that involve calculations. 1) Please name one conservative substitution for the following; do not use the same amino acid twice:a) Arg_____ pos charged AA ____b) Leu_______Branched AA________c) Asp_________Glu or Gln, Asnd) Thr____Ser e) Asn________Gln,_Asp, Glu______ . 2) Please solve for pKa if pH = 4.5, the concentration of A- is 10 mM, the concentration of HA is 100 M. μ. pH = pKa + log [A-]/[HA] 4.5 = x + log (10mM/0.1mM). You an write this as 4.5 = x+ log (10+1 mM/ 10-1 mM) and you know that when you divide exponents you subtract themso we get:. 4.5 = x+ log 10 (+1-(-1) So 4.5 x plus the log of 102, and all a log is, is the number to which 10 is raised. so the log of 102 = 2. 4.5 = X + 2 therefore 2.5 = X .. 3) Please solve for the charge on the peptide shown below at pH 2 and show your work:. +1 0 0 = +1 . 4) Please solve for ∆G when ∆S = 100 J/mole K, ∆T= 298 K, and ∆H = 0.1kJ/mole . Always write the equation First to receive partial credit: ∆G = ∆H-T∆S. ∆G = ∆H-T∆S where T is in Kelvin. Put these in the same terms. kilo-Joule works for me. So ∆S is 0.1 kJ mole-1 K-1 . ∆G= 0.1 kJ mole-1 - 298 K * 0.1 kJ mole-1 K-1 . ∆G= 0.1 kJ mole-1 - 29.8 kJ mole-1 = -29.7 kJ mole -1.. 5) Please identify the globin composition of: a. Adult hemoglobin________alpha2 Beta 2 b. Fetal hemoglobin________alpha 2 Gamma2_ . EC) What is the role of the distal histidine in hemoglobin function?_ The distal His helps to regulate the entry and exit form the Fe2+ O2 binding site. Large molecules like CO2 have a harder time getting in, and O2 is stabilized to leave as O2 and not superoxide, O2-. You had to mention both portions of these attributes entry and exit – 1not just say it’s a
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