5.2.2 Respiration Flashcards
Why do Organism need to respire? (Why do organisms need energy)
- Biological processes need ATP energy (Active transport)
- Movement of organisms (Cellular or Muscle contraction)
- Maintenance of body temperature
- Synthesis of DNA and Proteins
What are the structures of the mitochondrion?
- Inner and Outer mitochondrial membrane
- Cristae
- Matrix
- Mitochondrial DNA
What are the Stages of Respiration?
- Glycolysis
- Fermentation (anaerobic conditions)
- Link Reaction
- Krebs Cycle
- Oxidative phosphorylation
Where does Glycolysis Occur?
- Cytoplasm of the cell
Where does the Link reaction occur?
- Mitochondrial Matrix
What are the steps in Glycolysis (detail)?
- Phosphorylation: 2 Molecules of ATP release a phosphate which combines with glucose to form HEXOSE BISPHOSPHATE
- Lysis: The hexose bisphosphate splits into 2 molecules of TRIOSE PHOSPHATE
- Phosphorylation II: Another phosphate group is added to triose phosphate forming 2 molecules of TRIOSE BISPHOSPHATE
(inorganic phosphate is from the cytoplasm not ATP in this case) - Dehydrogenation and ATP formation: The two molecules of triose bisphosphate are oxidised and the phosphates removed to form 2 Pyruvates and 4 ATP and 2 NADH (reduced NAD which is used later in Oxidative Phosphorylation)
What are the steps in the Link reaction? (Oxidative decarboxylation)
- Pyruvate enters the Mitochondrial matrix via active transport
- Oxidative decarboxylation happens by removing a CO2 and a Hydrogen
- The hydrogen is accepted by NAD forming NADH (Reduction of NAD)
- COENZYME A bind to the two carbon group forming Acetyl CoA
- The NADH is used in Oxidative Phosphorylation and the Acetyl CoA delivers the Acetyl group to the Krebs cycle
Where does the Krebs cycle take place?
-Mitochondrial Matrix
What are the steps in the Krebs cycle?
- Acetyl CoA delivers the Acetyl group (2-C) which combines with OXALOACETATE (4-C) to form CITRATE (6-C)
- Decarboxylation & Dehydration of Citrate Produces CO2 and 1 NADH and a 5 carbon compound
- Further decarboxylation and Reduction regenerating OXALOACETATE
- CO2 2 NADH and FADH2 are produced
- ATP is also produced by substrate-level phosphorylation
What is the importance of coenzymes in respiration? (CoA NAD FAD)
- Transport protons, electrons and functional groups i.e. acetyl group
- NAD is present in all stages of cellular respiration
- NADH is oxidised at the start of the electron transport chain
- FADH2 is oxidised further along the transport chain
Where are coenzymes derived from?
- Vitamins
Where does Oxidative Phosphorylation occur?
- Inner membrane of the Mitochondrion
What happens in oxidative phosphorylation
- Coenzymes NADH & FADH2 are delivered to the electron transport chain
- Hydrogen atoms dissociate into Hydrogen ions and electrons
- Electron Carriers are reduced and oxidised by electrons as they flow along the electron transport chain
- The energy released by the redox reactions is used to create a proton gradient (electrochemical gradient)
- The H+ ions diffuse through ATP synthase where the energy released is used to combine ADP with inorganic phosphate to form ATP
- Oxygen acts as the final electron acceptor by combining with H+ to form H2O (water)
- Oxygen is needed to accept the electrons for the electron transport chain to continue
What are the benefits of being able to anaerobically respire?
- ATP can be produced in oxygen lacking environments
- Alcohol can be produced :)
What are two types of anaerobic respiration (yeast & mammals)?
- Lactate Fermentation (mammals)
- Alcoholic Fermentation (yeast)
What happens in Lactate fermentation? (mammals)
- Pyruvate acts as a hydrogen acceptor taking the hydrogen from NADH to reform NAD and produce LACTATE
- Catalysed by LACTATE DEHYDROGENASE
- The regeneration of NAD allows for glycolysis to continue
- Produces only 2 ATP
Where is Lactic acid converted back into glucose?
- The liver (requires oxygen)
Why can Lactate fermentation not continue indefinitely?
- Reduced production of ATP cannot sustain vital processes for long periods of time
- Lactic acid raised the pH which can denature enzymes
What happens in Alcoholic Fermentation?
- Pyruvate goes through decarboxylation forming ETHANAL and CO2
- Catalysed by pyruvate decarboxylase
- Ethanal accepts the Hydrogen from NADH
- Regenerates NAD and produces ethanol :)
- This can continue indefinitely in the absence of oxygen
- Yeast is unable to survive if too much ethanol accumulates
Why does anaerobic respiration have a lower yield of ATP than aerobic?
- Aerobic can use the NADH and the Pyruvate in the link reaction , Krebs cycle and Oxidative phosphorylation to produce ATP
- Anaerobic can only utilise glycolysis to form 2 ATP
What is the difference in energy values of Carbohydrates Protein and Lipids as respiratory substrates
Carbs: 1.0
Proteins: 0.9
Lipids: 0.7
RQ = ??
RQ = CO2 produced / O2 consumed
