Chapter 14 Energy generation in Mitochondria and Chloroplasts Not responsible for 1) Detailed mechanism of the Ps reaction center (Figure 14-33) 2) Photosynthesis in bacteria (pp 480-483) View The Virtual Cell animations for - e- transport - ATP synthase - photosynthesis Questions in this chapter you should be able to answer: Chapter 14: 1 - 4, 6 – 12, 14 - 23 Energy Generation

A Quick review… How is energy transferred to ATP? Substrate-level phosphorylation Pi comes from a substrate molecule Chemiosmotic phosphorylation ATP synthesis is coupled to NADH oxidation Energy Generation

How is oxidation of NADH coupled to ATP synthesis? E- transport - H+ pumping - ATP synthase Which creates a ‘proton-motive’ force through a H+ electrochemical gradient Energy Generation

What are consequences of DNP and nigericin on the proton gradient? What are the molecular components of the e- transport system? E- transport (Cyt b-c1) Question 14-3, p 457 What are consequences of DNP and nigericin on the proton gradient? Energy Generation

Why do e-transport proteins bind e- ? Iron-sulfur groups heme groups of cytochromes Why do electrons pass between e- transport proteins? Iron-sulfur groups lower redox potential = lower affinity for e- heme groups higher redox potential = higher affinity Energy Generation

Jmol ATP synthase model What is the mechanism the ATP synthase? ATP synthase can also function as an ATPase Jmol ATP synthase model ATP synthase Energy Generation

What is the evidence that ATP synthesis is driven by Chemiosmosis? Reconstituted systems Questions A) For system ‘B’ to function, what metabolites and pH conditions must exist outside and inside the vesicles? B) Suppose that system ‘B’ were constituted “inside out”. Diagram this scenario and explain why ATP synthesis would not occur. C) How could system ‘B’ be made to function as an ATPase? Energy Generation

Energy capture during photosynthesis What is the structure of chloroplasts? What are the two stages of Ps? Explain why the light-independent reactions only occur in the presence of light. Energy Generation

How is energy captured by chlorophyll? Antenna (‘light harvesting’) complex Reaction Center Chl Porphyrin ring Energy Generation

What does the Z-scheme show? PSII Reaction center - donates e- to platoquinone - replaces with e- from H2O What does the Z-scheme show? Energy Generation

How is ATP and NADH generated during the light reactions? Z-scheme P680 and P700 Rx centers Coupling to chemiosmosis NADP reduction Membrane architecture Question 14-10 p 477 Chloroplasts do not have an ATP transporter. How then do plant cells obtain ATP to carry out other metabolic processes? PS e- transport Energy Generation

How is CO2 ‘fixed’ into organic form? -- light-independent Rxs -- Calvin / Bensen cycle -- RUBP carboxylase oxygenase (Rubisco) 1. CO2 Fixation RUBP carboxylase-oxygenase (Rubisco) 2. Carbon Reduction 3. RUBP regeneration Energy Generation