Chapter 16, Problem 15P

(a)

Summary Introduction

To determine: The structure of intermediate which is accumulated when respiration is stopped

Introduction:

Mitochondria is the primary site of cellular respiration. Aerobic respiration takes place inside the mitochondria. -Mitochondria is isolated by cell disruption and centrifugation to study its various functions.

Given:

$0.01\text{M}$ of sodium malonate was added to mitochondria. If pyruvate is used as fuel by mitochondria then respiration process is stopped and the intermediate gets accumulated.

(b)

Summary Introduction

To explain: The reason of intermediate accumulation.

Introduction:

Succinate dehydrogenase -plays a major role in cellular respiration that monitors oxygen level which is found in the inner mitochondrial membrane. In pseudo-hypoxia conditions (low oxygen level), succinate dehydrogenate generates signals and send them to brain. It is given that $0.01\text{M}$ sodium malonate was added to mitochondria. If pyruvate is used as fuel by mitochondria then the respiration process is stopped and the intermediate gets accumulated.

(c)

Summary Introduction

To explain: The reason why the oxygen consumption stops.

Introduction:

All the metabolic reactions occur within the body which is interconnected through the intermediate products or final products. Inhibition of any of the intermediates or even the enzymatic activity can stop the cycle. Hence, further coming events will also stop.

(d)

Summary Introduction

To explain: The method to overcome the inhibition of respiration in isolated mitochondria.

Introduction:

Malonate is a competitive inhibitor that inhibits the activity of succinate dehydrogenase. Due to malonate activity, respiration stops eventually. To overcome the effect of the inhibition, it is sufficient to provide large amount of substrates such as succinate.