respiration

DEFINITION:the chemical energy in glucose must be released through a series of enzyme-controlled reactions in order to prevent damage to the cells, these reactions are called respiration

glucose is an energy rich food and it is the main source of energy in a living cell

muscle cells need energy to contract, like also energy is needed for cell division. the energy for this comes from ATP which has been produced during the respiration of glucose. 

diagram...

definition:respiration is the process by which energy is released during the breakdown of glucose. the energy released is used to make ATP. if oxygen is present cells carry out aerobic respiration

stage 1 - GLYCOLYSIS glycolysis is the first stage of aerobic respiration. in glycolysis, glucose is broken down into pyruvate in a series of enzyme controlled reactions this takes place in the cytoplasm of the cell glycolysis produces enough energy to make 2 molecules of ATP

stage 2 - BREAKDOWN OF PYRUVATE in the second stage pyruvate is broken down into carbon dioxide and water the energy released allows a large quantity of ATP is produced (36 ATP molecules) this happens in the mitochondria oxygen is needed for the complete breadown

ANAEROBIC RESPIRATION IN ANIMALS if oxygen is not avaliable or in short supply glucose can not be broken down completely into co2 and water glucose is only partly broken down and only 2 molecules are made this type of respiration is called anaerobic

stage 1 - ANAEROBIC RESPIRATION PATHWAY

glycolysis takes place in the same way as in anaerobic respiration in the absence of oxygen, pyruvate is changed into lactic acid

ANAEROBIC RESPIRATION IN PLANTS & YEAST in plants and yeast glucose is only partly broken down in the absence of oxygen without oxygen only glycolysis can take place the pyruvate formed is then further broken down into ethonal and co2 it is irreversible, this is because co2 is a lost gas. 

2 ATP molecules are formed during glycolysis which one is glucose no ATP are formed during the breakdown of the pyruvate molecule

respiration

aerobic respiration

glycolysis

breakdown of pyruvate

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