深圳大学：《植物生理学 Plant Physiology》课程教学资源（PPT课件）Chapter05 植物的呼吸作用 Respiration

Chapter 5 Respiration

Chapter 5 Respiration

Carbon metabolism Carbon cycles through photosynthesis and respiration. Energy (light) Photosynthesis CO H. Carbohydrates Respiration Energy(ATP)<

Respiration

Respiration  Definition: ➢ The oxidative process occurring within living cells by which the chemical energy of organic molecules is released in a series of metabolic steps involving the consumption of oxygen and the liberation of carbon dioxide and water. • Excerpted from The American Heritage® Dictionary of the English Language, Third Edition © 1996 by Houghton Mifflin Company

Fuel for Respiration

“Fuel” for Respiration  E.g. starch, glucose, fructose, and sometimes amino acids, organic acids or fats. ➢ We will focus on respiration of monosaccharides (e.g. glucose). ➢ Polysaccharides (e.g. starch) first need to be broken down into monosaccharides. ➢ Fats and amino acids enter the respiratory pathway at different points

Overview Energy

Overview ➢ Photosynthesis occurs in chloroplasts (chlorophyll) mostly in the green leaves. ➢ Carbohydrates produced in leaves are translocates throughout the plant (phloem). ➢ Carbohydrates are oxidized at destination sites to release energy, CO2 & water =RESPIRATION. • Sugar + O2 = CO2 + Water + Energy

Overview

Overview ➢ Photosynthesis: reduction of CO2 . ➢ Respiration: oxidation of carbohydrate. ➢ Different: • energy transfer • enzymes • locations • cell types

Aerobic VS, Anaerobic Resp. Aerobic respiration oXgen yruvate NADH Lactate CO2 dehydrogenase NAD+k Pyruvate Lactate I decarboxylase Acetaldehyde NADH Alcoh dehydrogenase NAD Fermentation Ethanol reactions

Aerobic vs. Anaerobic Resp. ➢ Aerobic respiration = with oxygen . • Complete oxidation. • Waste products: H2O, CO2. • Energy captured for use: ~36 ATP/glucose. ➢ Anaerobic respiration = without oxygen. • Lactic acid or ethanol produced. • Energy trapped: 6 ATP

obic Resn peaction

Aerobic Resp. Reaction C6H12O6 (glucose) + 6 O2 => 6 CO2 + 6 H2O + 2870 KJ Energy ➢ The reverse of photosynthesis. ➢ Glucose is being oxidized ➢ Accompanied by the release of free energy

naerobic Resp. Reaction

• C6H12O6 => 2C2H5OH + 2CO2 + 100 KJ Energy • C6H12O6 => 2CH3CHOHCOOH + 100 KJ Energy Anaerobic Resp. Reaction

ammirati

Significance of Respiration ➢ Retrieving the energy stored in the photosynthesis, and provide energy for overall cell metabolism. ➢ Obtain carbon skeletons that are used to build other molecules required by the growth and maintenance of the cell