chapter  1
64 Pages

1

Introduction .............................................................................. 2 Anatomy and Physiology of the Mitochondrion..................... 3

Structural Components................................................... 3 Membranes ...................................................................... 5

Diet Effects on Membrane Lipid Composition and Structure .................. 12

Age Effects on Membrane Lipids ...................... 18 Membrane Function ........................................... 20

Metabolic Systems in Mitochondria ..................................... 22 Fatty Acid Oxidation ..................................................... 22 Ketogenesis .................................................................... 26 Gluconeogenesis............................................................. 27 Urea Cycle ..................................................................... 30 Shuttle Systems ............................................................ 33 The Citric Acid Cycle .................................................... 37 The Respiratory Chain ................................................. 39 Oxidative Phosphorylation ........................................... 44

Uncoupling Proteins...................................................... 48 Adenine Nucleotide Translocation ............................... 51 Metabolic Control .......................................................... 52 Ion Flux-Role of Calcium.............................................. 54

Summary ................................................................................ 55 References............................................................................... 56

INTRODUCTION

The mitochondria are organelles suspended in the cytoplasm that are the powerhouses or power plants of the cell. It is this organelle that traps the energy released by oxidative reactions in the high-energy bond of ATP. This trapping occurs through the process of coupling the synthesis of water via the respiratory chain to the synthesis of ATP via the F

F

ATPase in a process called oxidative phosphorylation (OXPHOS). The mitochondria have other functions as well. Fatty acid oxidation and the citric acid cycle occur here and gluconeogenesis and urea synthesis begin in this compartment. The mitochondria play a role in apoptosis and have the components for the synthesis of a few proteins of OXPHOS.