Chapter 8, Problem 39A

Summary Introduction

To discuss:

The place from wherein cellular respirationdoes electrons in the electron transport chain come from and their final destination

Introduction:

Organisms obtain energy through a process called cellular respiration. This process occurs in two stages; glycolysis and aerobic respiration. Glycolysis is an anaerobic process while aerobic respiration includes Krebs cycle and electron transport.

Answer to Problem 39A

The high energy electrons in electron transport system come from NADH and FADH₂.

Oxygen is the final electron acceptor in electron transport system.

Explanation of Solution

The final step in breakdown of glucose is electron transport during which high energy electrons and hydrogen ions from NADH and FADH₂ are used to convert ADP to ATP. As NADH and FADH₂ release electrons, the energy carriers are converted to NAD+ and FAD. H+ ions are pumped into the mitochondrial matrix. These ions diffuse down their concentration gradient back across the membrane and into the matrix through ATP synthase molecules in chemiosmosis. Oxygen is the final electron acceptor in electron transport system. Protons and electrons are transferred to oxygen to form water.