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respiration test question upgrades - Coggle Diagram
respiration test question upgrades
The diagram represents two of the stages of aerobic respiration that take place in a mitochondrion
name substance X
a) pyruvate
Which stage of aerobic respiration takes place inside a mitochondrion and is not represented on the diagram
krebs cycle
Explain why oxygen is needed for the production of ATP on the cristae of the mitochondrion
Oxygen is needed for the production of ATP because it is the final electron acceptor and without it aerobic respiration would stop and anaerobic respiration could occur. ATP is formed as electrons pass through the electron transport chain. The reduced coenzymes (NAD and FAD) are oxidised.
Describe the process of glycolysis
Glycolysis is the first stage of aerobic/anaerobic respiration and does not require oxygen. Glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP. Glucose is split using a molecule of water (hydrolysis). 2 molecules of triose phosphate are formed and 2 molecules of ATP are used up. 4 ATP are produced but 2 were used at the start so there is a net production of 2 ATP. Coenzyme NAD collects hydrogen ions forming 2 NADH. Triose phosphate is oxidised forming 2 molecules of pyruvate.
Malonate inhibits a reaction in the Krebs cycle. Explain why malonate would decrease the uptake of respiration in a respiring unit
Oxygen is the final electron acceptor. This means fewer hydrogen ions are removed and passed to the electron transport chain and so therefore there is a loss of reduced NAD.
Describe how ATP is made in the mitochondria
During glycolysis 2 ATP is formed from the oxidation of triose phosphate into pyruvate. The link reaction reduces coenzymes NAD and FAD to NADH and FADH. Electrons are released from coenzymes then passed through the electron transport chain through a series of redox reactions. Energy is released through these reactions and the reaction between ADP and Pi. Protons are moved into the intermembranal space and ATP synthase releases ATP.
Describe how acetyl coenzyme A is made in the link reaction
Pyruvate from glycolysis is decarboxylated meaning a carbon dioxide is lost from the reaction to form acetate. Then a hydrogen is lost from the reaction and coenzyme A is added to form acetyl coenzyme A.
In the Krebs cycle acetyl coenzyme A combines with four carbon oxaloacetate to form six carbon citrate. This reaction is catalysed by the enzyme citrate synthase. Oxaloacetate is the first substrate to bind with the enzyme citrate synthase. This induces a change in the enzyme which enables the acetyl coenzyme A to bind. Explain how oxaloacetate enables the acetyl coenzyme A to then bind to the enzyme.
When oxaloacetate binds to the enzyme it changes the shape of the active site so it is now complementary to the substrate.
Another substance in the Krebs cycle is called succinyl coenzyme A. This substance has a very similar shape to acetyl coenzyme A. Suggest how production of succinyl coenzyme A could control the rate of the reaction catalysed by citrate synthase.
The competitive inhibitor succinyl coenzyme A attaches to the active site of citrate synthase meaning that the true enzyme substrate complexes between acetyl coenzyme A and citrate synthase cannot form and the rate would slow.
In muscles, pyruvate is converted to lactate during anaerobic respiration. Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration.
NAD is regenerated and used in glycolysis