Energy Generation 1

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)

Questions in this chapter you should be able to answer:Chapter 14: 1 - 4, 6 – 12, 14 - 23

View The Virtual Cell animations for - e- transport - ATP synthase - photosynthesis

Energy Generation 2

A Quick review…

How is energy transferred to ATP?

Substrate-level phosphorylationPi comes from a substrate molecule

Chemiosmotic phosphorylationATP synthesis is coupled to NADH oxidation

Energy Generation 3

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 4

What are the molecular components of the e- transport system?

Question 14-3, p 457What are consequences of DNP and nigericin on the

proton gradient?

(Cyt b-c1)

E- transport

Energy Generation 5

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

Why do e-transport proteins bind e- ?Iron-sulfur groups heme groups of cytochromes

Energy Generation 6

What is the mechanism the ATP synthase?

ATP synthase can also function as an ATPase

ATP synthase

Jmol ATP synthase model

Energy Generation 7

What is the evidence that ATP synthesis is driven by Chemiosmosis?

Reconstituted systems

QuestionsA) 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 8

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 9

How is energy captured by chlorophyll?

Antenna (‘light harvesting’) complex

Reaction Center Chl

Porphyrin ring

Energy Generation 10

What does the Z-scheme show?PSII Reaction center

- donates e- to platoquinone

- replaces with e- from H2O

Energy Generation 11

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 477Chloroplasts do not have an ATP transporter. How then do plant

cells obtain ATP to carry out other metabolic processes?

PS e- transport

Energy Generation 12

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