University of South Florida: BIO CHEMIST 3053. Biochemistry-Gift-2-Spring-2019. All ANSWERS 100% CORRECT AID GRADE ‘A’

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Old Biochem Exam 2 Biochemistry 3053 GIFT 2 Possible Questions: BLUE Possible Answers: From Previous GIFT: Yellow Highlight Notes: GREEN 1. Which enzyme is considered [REDACTED]? Part of TCA and ETC? ... Rate limiting: 1. Which enzyme is considered part of TCA and ETC? A. Malate dehydrogenase B. Citrate synthase C. Isocitrate dehydrogenase D. NADH- ubiquinone oxidoreductase 2. A solution at pH [REDACTED] contains a weak acid, HA. The pKa of the acid is [REDACTED]. What is the ratio of [A- ]:[HA]? pH=7 pKa=6.5 pH= pka + log ([A- ]/[HA]) 7= 6.5 + log ([A- ]/[HA]) log ([A- ]/[HA])= 0.5 ([A- ]/[HA])= 100.5 = 3.162271766017 ratio of [A- ]:[HA]= 3.16:1 3. In mitochondria, what is the expected pH [REDACTED]? In mitochondria, what is the expected pH of the matrix compared to the intermembrane space? 4. When Compound C [REDACTED] electrons [REDACTED] Compound D, [REDACTED] When Compound C gives electrons to Compound D, then Compound D is the oxidant and Compound C is the reductant. When Compound C removes electrons from Compound D, then Compound C is the oxidant and Compound D is the reductant 5. When Compound C [REDACTED] electrons [REDACTED] Compound D, [REDACTED] When Compound C gives electrons to Compound D, then Compound D was reduced and Compound C was oxidized. When Compound C removes electrons from Compound D, then Compound C is reduced and Compound D was oxidized 6. What provides the energy to the ATP Synthase for the formation of ATP? - ADP + Pi + H+out ⇌ ATP + H2O + H+in When protons flow back down their concentration gradient (from the intermembrane space to the matrix) 7. Which of the following describe cristae? - Cristae do not have pores for movement of proteins - Their proteins are not found in outer membrane - Cristae does not seal inner membrane - Cristae does not anchor f1f0 ATP synthase - THEY INCREASE SURFACE AREA OF INNER MEMBRANE 8. (True / False) The amino acid [REDACTED] at pH 7.4 has [REDACTED] charged groups. - Amino acid T at pH 7.4 has two charged groups but net charge of 0 - Amino acid H at pH 7.4 has two charged groups but net charge of 0. - Amino acid E at pH 7.4 has two charged groups but net charge of 0 -(True / False) The amino acid [aspartic acid or glutamic acid] at pH 7.4 has [a negative (T/F) The amino acid [aspartate] at pH 7.4 has [three] charged groups T Congratulations! Due to your success in Dr. Daniel’s Biochemistry class. You have been selected by NASA to do the biochemical write up on a new organism recovered from a Martian probe! During your analysis you have discovered a brand new electron transport chain! The organism appears to use electron transport as its primary source of energy rather than ATP. This leaves you with a couple of questions to answer: During analysis, your technician reports a new electron transport chain (always check your technician’s work! Analyze this carefully!): Ickygreenone + H+ + 2e- → Ickygreenol [REDACTED] V -0.2 V Barsool → Barsoom + H+ + 2e- [REDACTED] V 0.03 V Because the reactions are not originally in the same form we would flip the bottom reaction to have the oxidized form accepting electrons to become the reduced form so we can determine which half reaction is the stronger reductant This would give: Ickygreenone + H+ + 2e- → Ickygreenol (-0.2 V) Barsoom + H+ + 2e- → Barsool (-0.03 V) Both half reactions are now in the same form so we can confirm that the top reaction is the most negative of the two half reactions and the stronger reductant **If we want to solve for ΔE0 we would flip the top reaction to make the electrons flow, which would give: Ickygreenol → Ickygreenone + H+ + 2e- (0.2 V) Barsoom + H+ + 2e- → Barsool -0.03 V (-0.03 V) **to determine, reductant, oxidant, reduced, and oxidized you would look at the half reactions when they are in the same form (before the stronger reductant becomes flipped) So this: Ickygreenone + H+ + 2e- → Ickygreenol (-0.2 V) Barsoom + H+ + 2e- → Barsool (-0.03 V) 9. Which species is the reductant for the proposed ETC? Reductant relates to oxidized so Ickygreenol and Barsool are the reductants The stronger reductant would be Ickygreenol because it is the most negative **Smaller Ev value is more negative 10. Which species is the oxidant for the proposed ETC? Oxidant relates to being reduced so Ickygreenone and Barsoom are the oxidants because they have gained electrons ← this is just how I understand it The stronger oxidant would be Barsoom because it is the most “positive” **Larger Ev value is more positive 11. Which series of voltages represents the correct voltages to trace the electron flow for the free energy calculation? If this is what we originally had: Ickygreenone + H+ + 2e- → Ickygreenol (0.5 V) Barsoom + H+ + 2e- → Barsool (1.25 V) Then 0.5 would be flipped because it is the most “negative” out of the two voltages This means the top equation has the strongest reductant This would give: Ickygreenol → Ickygreenone + H+ + 2e- (-0.5 V) Barsoom + H+ + 2e- → Barsool (1.25 V) If this is what we originally had: Ickygreenone + H+ + 2e- → Ickygreenol (-0.5 V) Barsoom + H+ + 2e- → Barsool (-1.25 V) Then -1.25 would be flipped because it is the most “negative” out of the two voltages This means the bottom equation is the strongest reductant This would give: Ickygreenone + H+ + 2e- → Ickygreenol (-0.5 V) Barsool → Barsoom + H+ + 2e- (1.25 V) a) -0.5V and -1.25V b) +0.5V and -1.25V c) -0.5V and +1.25V d) +0.5V and +1.25V 12. What is the free energy from the electron transport chain presented (Faraday constant is 23)? ***Use the equation ΔG॰= (-n)(F)Ecell ½ O2 + 2H+ + 2e- → H2O (0.82 V) Dehydroascorbate + 2e- → Ascorbate (0.08 V) Both half reactions are in the same form, in order for electrons to flow we need to flip the stronger reductant The stronger reductant would be the bottom half reaction because it is more “negative” We get: ½ O2 + 2H+ + [Show More]

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