Higher Human Biology Subtopic 7 (a) Respiration Metabolic Pathways Higher Human Biology Subtopic 7 (a) Respiration

Learning Intentions State the equation of respiration Describe the structure of ATP State the role of ATP in the transfer of energy Discuss the 3 stages in aerobic respiration

What can we remember? Respiration is a series of enzyme controlled reaction that releases the energy in food to make ATP.

Why do cell need energy? Growth Cell division Repair Movement (e.g. muscular contraction) Chemical reactions (e.g. protein synthesis) Remember ATP links catabolic and anabolic reactions.

Adenosine tri phosphate ATP Adenosine tri phosphate Energy currency of the cell Stores energy 1 adenosine + 3 inorganic phosphates ADENOSINE Pi

Adenosine di phosphate Energy Release The energy stored in ATP is released when the bond to the last phosphate is broken to produce………… Adenosine di phosphate ADENOSINE Pi Energy

ATP is a link between anabolic and catabolic reactions. The Reversible Reaction There is a constant supply of ATP in our cells as it is synthesised as fast as it is used. REMEMBER…… ATP is a link between anabolic and catabolic reactions.

Phosphorylation An enzyme controlled process Involves the addition of a phosphate group Also occurs when the Pi and energy from ATP are transferred.

Respiration The Process

ANAEROBIC RESPIRATION The Equations AEROBIC RESPIRATION - Presence of oxygen ANAEROBIC RESPIRATION - Lack of oxygen

Overview (aerobic respiration) Energy rich substance (e.g. glucose) is broken down and used to make ATP Enzyme controlled steps 3 stages : 1. Glycolysis 2. Citric Acid Cycle 3. Electron Transport Chain (ETC) Requires the enzyme ATP synthase

Overview (aerobic respiration) Cristae (folds in the inner membrane) Central matrix (fluid filled interior)

Stage 1 : Glycolysis Occurs in the cytoplasm Doesn’t need oxygen Splits 6C glucose into 2 × 3C pyruvates Hydrogen ions and electrons removed Net gain of 2 ATP

The energy investment stage Phosphorylation happens twice (step 1 and step 3) Step 3 uses the enzyme phosphofructokinase

The energy payoff stage 4 ATP generated here (2 needed in energy investment stage) so NET GAIN of 2 ATP H+ ions and electrons released by the action of a dehydrogenase enzyme and picked up by the coenzyme NAD to form NADH NADH goes to the ETC

Textbook page 103 If there is no oxygen present then the reaction does not proceed to TCA

Stage 2 : Citric Acid Cycle Occurs in the matrix of the mitochondria Needs oxygen Converts pyruvate into Acetyl which combines with coenzyme A to make acetyl coenzyme A

Stage 2 : Citric Acid Cycle Acetyl coenzyme A is broken down in a series of steps releasing H+ ions, electrons and carbon dioxide The H+ ions and electrons are picked up by NAD / FAD

Stage 3 : Electron Transport Chain Occurs on the cristae of the mitochondria Contains a group of proteins attached to the inner membrane and the enzyme ATP synthase Proteins ATP Synthase Intermembrane space Matrix

Stage 3 : Electron Transport Chain The NADH / FADH2 release their high energy electrons The electrons release their energy which is used to pump H+ across the membrane (matrix to inter membrane space) This forms a gradient (more H+ in intermembrane space) The H+ flow back through the enzyme ATP synthase synthesizing ADP + Pi ATP The electrons, a pair of H+ and oxygen combine to form water.

TOTAL ATP = 38 ATP Production 2 ATP from glycolysis 36 ATP formed in the rest of the cycle (nearly all in the ETC) TOTAL ATP = 38 ETC clip

Put the following statements under the correct stage in respiration….. It ends with the production of water It brings about the breakdown of glucose to pyruvate It involves the production of CO2 It begins with acetyl coA combining with oxaloactetate It involves a cascade of electrons, which are finally accepted by oxygen It results in the production of ATP It has an energy investment and an energy payoff stage It results in the production of NADH

Learning Intentions State the equation of respiration Describe the structure of ATP State the role of ATP in the transfer of energy Discuss the 3 stages in aerobic respiration