Compare aerobic respiration with photosynthesis Summary questions and application to check understanding of aerobic respiration Describe and explain the reactions of anaerobic respiration

Summary qs p 57 1.Oxidative phosphorylation… involves loss of electrons to oxygen. Phosphorylati ons means a phosphate group is added to ADP. 1.Folded cristae give a large SA for attachment of molecules in the etc 2.Oxygen is the final electron acceptor, and accepts hydrogen ions. With no oxygen, respiration stops after pyruvate. 3.Oxygen leaves as part of water

Application p57

What stages of respiration produce hydrogen ions and therefore reduced NAD? Glycolysis, link reaction and the Krebs Cycle What happens to these hydrogen ions during the electron transport chain? It is pumped through the membrane and eventually combines with oxygen to form water. Movement of H+ is used to make ATP

What would happen if there is insufficient oxygen available? Which stages of respiration could not occur? Reduced NAD would not be oxidised and NAD regenerated. Processes which produced reduced NAD would grind to a halt as no more NAD would be available to be reduced. link reaction and the Krebs cycle and etc would stop occurring

When there is insufficient oxygen for aerobic respiration, e.g. during heavy exercise, an alternative means of removing hydrogen from reduced NAD to convert it back into NAD must be found. Glycolysis still occurs, producing………………… but this then enters an alternative pathway.. Pyruvate (the end product of glycolysis) accepting the hydrogen from reduced NAD. Anaerobic respiration occurs but produces much less ATP than aerobic respiration.

2ADP + 2P i 2ATP NAD Reduced NAD NAD The NAD is regenerated And can be used again in glycolysis NAD Reduced NAD NAD

Overall Equations: In plants: Pyruvate + reduced NAD ethanol + carbon dioxide + NAD

In animals: Pyruvate + reduced NADlactate + NAD This is particularly common in muscle cells during strenuous exercise. If lactate accumulates it can cause cramp and muscle fatigue. Some lactate enters the bloodstream and is taken to the liver and converted into glycogen. After exercise when sufficient oxygen is available the oxygen debt must be repaid and the lactate oxidised back to pyruvate. The pyruvate can then be oxidised for energy or converted into glycogen for storage.

Anaerobic Respiration GLUCOSE STORED GLYCOGEN LACTIC ACID PYRUVATE CO 2 + Water Aerobic Conditions High Energy Demand Aerobic Conditions Anaerobic Conditions normal energy demand