Respiration

• Site of glycolysis

  Cytosol
• NAD


  Nicotinamide adenine dinucleotide
• Main steps in glycolysis


  Phosphorylation lysis phosphorylation dehydrogenation formation of ATP
• What happens in the first step of glycolysis (Phosphorylation)?


  2 ATP molecules are hydrolysed to release two phosphates, both attached to a glucose molecule, forms hexose bisphosphate
• What happens in the second step of glycolysis (Lysis)?

  Phosphorylation destabilises the molecule, splits into two triose phosphate molecules
• What happens in the third step of glycolysis (Phosphorylation)?

  Inorganic phosphate group is added to a triose phosphate molecule to form two triose diphosphate molecules
• What happens in the fourth step of glycolysis (Dehydrogenation and formation of ATP)?

  Two triose bisphosphate molecules are oxidised by the removal of hydrogen atoms, forms two pyruvate molecules, NAD coenzymes accept the removed hydrogens and are reduced to form two reduced NAD molecules, 4 ATP molecules are produced using phosphates from the triose bisphosphate molecules
• What is the kind of phosphorylation done in glycolysis?


  Substrate level phosphorylation
• What happens in the link reaction?

  Pyruvate enters the mitochondrial matrix by active transport by carrier proteins, pyruvate is dehydrogenated and decarboxylated, hydrogen atoms given to NAD to form NADH, resulting two carbon acetyl group is bound to coenzyme A to form acetylcoenzyme A
• Technical name for the removal of carbon dioxide and hydrogen from the pyruvate

  Oxidative decarboxylation
• Substrate level phosphorylation

  When a phosphate group is transferred from one substrate to another
• First step of the Krebs Cycle

  Acetyl group combines with oxaloacetate to mak citrate
• Second step of the Krebs Cycle

  Citrate is decarboxylated and dehydrogenated, one molecule of reduced NAD and a 5 carbon compound is made
• Equation for the formation of reduced NAD


  NAD^+ + 2H^+ + 2e^- -> NADH + H^+
• Third step of the Krebs Cycle

  Alpha ketoglutarate is decarboxylated and dehydrogenated, one molecule of reduced NAD and a 4 carbon compound is made
• Fourth step of the Krebs Cycle

  4 carbon compound isomerised, one molecule of ATP made by substrate-level phosphorylation
• Fifth step of the Krebs Cycle

  4 carbon compound dehydrogenated, one molecule of FADH2 is made
• Sixth step of the Krebs Cycle

  4 carbon compound dehydrogenated, one molecule of NADH made, oxaloacetate regenerated
• Products of the Krebs Cycle (Both cycles)

  6 NADH, 2 FADH2, 2 ATP, 4CO2
• Role of electron carriers in oxidative phosphorylation


  To dissociate hydrogen into a proton and an electron, to pass electrons along the chain so energy is released
• Role of oxygen in oxidative phosphorylation

  Final electron acceptor, forms water
• Equation for the formation of water in oxidative phosphorylation

  O2 + 4H+ + 4e- -> 2H2O
• Where does oxidative phosphorylation happen?


  Inner mitochondrial membrane
• Process of oxidative phosphorylation

  NADH is oxidised and donates hydrogen to NADH dehydrogenase, hydrogen dissociates into a proton and an electron, electrons are passed along the electron carriers, releases energy, energy used to pump protons through the inner mitochondrial membrane, proton gradient forms, potential energy builds up, protons flow down gradient, allows ATP to form by ATP synthase
• Oxidative phosphorylation


  The production of ATP in the presence of oxygen
• What is ATP made from in oxidative phosphorylation?

  ADP and Pi
• Chemiosmosis


  The diffusion of protons down a concentration gradient through a partially permeable membrane
• Role of the electron transport chain in chemiosmosis

  The protons are actively pumped into the intermembrane space using energy released from the transport of electrons down the chain
• Role of proton gradients in chemiosmosis

  Protons diffuse down the proton gradients through ATP synthase in the inner mitochondrial membrane
• Role of ATP synthase in chemiosmosis

  Protons diffuse down the proton gradient through ATP synthase which releases the energy required to synthesise ATP
• Similarity between oxidative phosphorylation and photophosphorylation

  Both use ATP synthase and chemiosmosis
• Fermentation


  Breakdown of complex organic compounds into simpler inorganic compounds without the use of oxygen or the involvement of an electron transport chain
• Type of fermentation that occurs in mammals

  Lactate fermentation
• Process of lactate fermentation

  Pyruvate acts as an hydrogen acceptor which oxidises the NADH, catalysed by lactate dehydrogenase, pyruvate converted to lactate, NAD regenerated, used to keep glycolysis going so small amount of ATP made
• What is the reason for the oxygen debt that follow exercise?


  Conversion of lactic acid to glucose requires oxygen
• Why can't lactate fermentation continue indefinitely?

  Reduced quantity of ATP wouldn't be enough to maintain vital processes, accumulation of lactic acid would decrease pH which would denature proteins
• Type of fermentation that yeast does


  Alcoholic fermentation
• Process of alcoholic fermentation


  Pyruvate converted into ethanal, catalysed by pyruvate decarboxylase, ethanal can oxidise NADH, ethanal becomes ethanol, NAD can be used to continue glycolysis
• Benefits of being able to respire anaerobically

  Anaerobic respiration is fast, failsafe for emergency situations, allows some organisms to survive in low-oxygen environments
• Why does anaerobic respiration produce a much lower yield of ATP than aerobic respiration?

  Organic compounds aren't completely broken down, small quantity of ATP is synthesised by substrate-level phosphorylation aloneSee an expert-written answer!We have an expert-written solution to this problem!