The process of recharging ATP Textbook pp 95-100 Cellular respiration The process of recharging ATP Textbook pp 95-100

You think… The release of energy from food Is ‘Respiration’ the same as ‘Breathing’?? No. Respiration is…. The release of energy from food

ATP ATP is an energy carrier within the cell ATP can’t be stored nor can it be exported, so it must be used as it is produced

The Regeneration of ATP Cellular respiration is the process that recharges ATP Go to TB p 95 A living organism uses ATP continuously, but ATP is a renewable resource that can be regenerated by the addition of phosphate to ADP. The energy for this comes from the breakdown of food molecules.

Other Carriers Go to p 96

The need for energy Think of 5 reasons a human body, including all its cells, needs energy creation (such as protein and polysaccharide manufacture) active transport (ion pumps, cytosis) movement (microtubules, actin and myosin filaments, cilia) generate heat to maintain body temperature

Cellular respiration Look up the equation for cellular respiration. Complete Worksheet

Cellular respiration The complete oxidation of glucose involves over 20 different reactions, each catalysed by a different enzyme. Respiration does not break down glucose in a single step. Instead, glucose is broken down gradually releasing about 35% of the available energy to produce ATP. The rest is lost as heat energy

Overview of respiration 3 major processes Glycolysis The Krebs Cycle Electron Transport

Use your Text Books to match the steps to their major functions and correct order The breakdown of 6 Carbon Glucose to two 3 Carbon Pyruvate Occurs in the cytoplasm NAD carriers get filled with Hydrogen to form NADH Occurs in the inner matrix of the mitochondria The stage where most ATP are charged up Electrons are passed over cytochromes in the on the membranes of the mitochondria Step 1. 2. 3 Electron Transport Glycolysis The Krebs Cycle

CELLULAR RESPIRATION 2 Learning Intentions: Understand GLYCOLYSIS Understand Formation of Acetyl CoA HW – WB pp 158

Glycolysis Taking a 6 Carbon Glucose and breaking it into two 3 Carbon molecules. 2 molecules of ATP are used, but 4 are given off. Therefore, we have a net (overall) gain of 2 ATP

Process 1: Glycolysis Net yield is: 2ATP, 2NADH & 2 pyruvate

Link reaction between Glycolysis and The Krebs Cycle: occurs in the mitochondrial matrix The pyruvic acid in Glycolysis loses a Carbon (through the creation of a CO2) It is now a 2 Carbon compound called acetyl Acetyl is carried by Coenzyme A – together they are Acetyl CoA Acetyl CoA moves to the Krebs Cycle.

CELLULAR RESPIRATION 3 Learning Intentions: Identify Mitochondrial structure Understand Electron Transport

First - Mitochondria Use TB p 81 to label this

Krebs cycle (citric acid cycle): takes place in the mitochondrial matrix See TB p 98 The major points: The acetyl group (created in the linking reaction) passes into a cycle of reactions . The acetyl group (2 C) combines with a 4C group to create a 6C molecule 2 lots of Carbon Dioxide are released (waste) 2 ATP produced Many NADs fill with Hydrogen to form NADH2 The NADH2s are transported to the electron transport chain Because we lost 2C molecules in our waste, we are now back to the start.

Electron & H+ transport coupled with ATP synthesis

Electron transport chain: takes place in and across the cristae It is at this point most of the ATP molecules are charged One molecule of glucose charges up to 38ATP, with 34 able to be charged in the electron transport chain NADH2 arrive from glycolysis and Krebs cycle, bringing in Hydrogens The hydrogens and electrons are passed down the electron transport chain. ATP is produced

respiration of 1 molecule of glucose Process ATP produced glycolysis 2 Krebs cycle Electron transport 34 Net ATP yield 38 Cellular respiration song

CELLULAR RESPIRATION 4 Learning Intentions: Distinguishing between aerobic and anaerobic respiration

Other substrates for respiration Starch Glycogen Triglycerides (fatty acids are broken down into 2C molecules and enter the Krebs cycle as acetyl CoA; glycerol enters glycolysis as a triose phosphate) Proteins (very rarely: amino acids are deaminated and converted into pyruvate, acetyl CoA or Krebs cycle intermediates)

Aerobic respiration When oxygen is present, pyruvate follows a certain pathway: It enters the mitochondria and undergoes a link reaction The product of the link reaction enters the Krebs cycle (or Citric acid cycle) And finally, H atoms (H+ and e-), that have been removed during the steps above, enter the electron transport chain

Anaerobic respiration Occurs in the cytoplasm Does not require oxygen but does occur in its presence Still involves Glycolysis, but does not follow through the Acetyl CoA Link reaction Generates a very small amount of ATP Produces poisonous bi-products

Fate of pyruvate when there is no oxygen Alcoholic fermentation in yeast cells Lactic acid fermentation in muscle cells Lactic acid is transported to the liver and oxidised to pyruvate & then to glucose. The oxygen needed for this is called the ‘oxygen debt’ of anaerobic respiration