Respiration

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  • Created by: Labake
  • Created on: 14-10-14 10:16
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  • Respiration
    • Why do living organisms respire?
      • Potential chemical energy in large organic molecules
      • Kinetic energy in moving molecules
      • Reactions that take place in organisms and require energy are metabolic
        • E.g. Active transport, Secretion, Endocytosis, Synthesis of large molecules, Replication of DNA and synthesis of organelles, Movement (muscle contraction).
      • Energy comes from sunlight for photoautotrophs- making large organic molecule that have chemical potential energy-Respiration used to release this energy and its stored in ATP when ADP is phosphorylated
      • ATP is Adenosine Triphosphate- 30kJ of energy made/released- found in prokaryotic and eukaryotic cells- made by ATP synthase, split by ATPase
    • Coenzymes
      • Dehydrogenase enzymes needed in Glycolysis, Link and Krebs
      • Coenzymes needed to help catalyse oxidation and reduction reactions
        • E.g. NAD combines with H atoms to inner mitochondrial membranes for oxidative phosphorylation
          • Combine = reducedNAD, release= oxidisedNAD (just NAD)
          • Nicotinamide Adenine Dinucleotide
        • E.g. Coenzyme A combines with Acetate (Acetyl CoA) for link to Krebs
          • Coenzyme A also combines with Acetate from Fatty Acids (B-oxidation) to Krebs Cycle
    • Glycolysis
      • Occurs in the cytoplasm of all cells (prokar and erukar)
      • STAGE 1: Glucose phosphorylated to Fructose-1-phosphate (activated)
        • ATP is hydrolysed to release phosphate
        • STAGE 1: Fructose-1-phosphate phosphorylated to Hexose Bisphosphate
          • ATP is hydrolysed to release phosphate
      • STAGE 2: Hexose Bisphosphate split into 2x Triose Phosphate
      • STAGE 3: Triose phosphate molecules oxidised (x2 hydrogen atoms removed) by NAD
        • 2x ATP molecules made when TP is phosphorylated (substrate level phosphorylation)
        • NAD to redNAD using dehydrogenase enzymes
      • STAGE 4: Intermediate product (3C) converted to x2 Pyruvate
        • x2 ADP phosphorylated to ATP (substrate level phosphorylation)
    • The Link Reaction and Krebs Cycle
      • Pyruvate dehydrogenated and decarboxylated to Acetate
      • Acetate reacts with Coenzyme A to Acetyl CoA
        • Acetate (2C) reacts with Oxyloacetate (4C) maing Citrate (6C)
          • Citrate dehydrogenated and decarboxylated to (5C)
            • Makes CO2 and redNAD
            • (5C) decarboxylated and dehydrogenated to (4C)
              • Makes CO2 and redNAD
              • (4C) to another (4C) phosphate released by hydrolysis
                • ADP phosphorylated to ATP
                • (4C) to another (4C) releasing x2 H atoms
                  • FAD reduced to redFAD
                  • (4C) to Oxyloacetate
                    • Acetate reacts with Coenzyme A to Acetyl CoA
                      • Acetate (2C) reacts with Oxyloacetate (4C) maing Citrate (6C)
                        • Citrate dehydrogenated and decarboxylated to (5C)
                          • Makes CO2 and redNAD
                          • (5C) decarboxylated and dehydrogenated to (4C)
                            • Makes CO2 and redNAD
                            • (4C) to another (4C) phosphate released by hydrolysis
                              • ADP phosphorylated to ATP
                              • (4C) to another (4C) releasing x2 H atoms
                                • FAD reduced to redFAD
                                • (4C) to Oxyloacetate
                                  • NAD reduced to redNAD
                    • NAD reduced to redNAD
      • Two turns for 1 glucose molecule
    • Structure and function of mitochondria
      • 0.5 to 1.0 micrometres in diameter and 2 to 5 micrometres long
      • INNER MEMBRANE: Phospholipid- impermeable to most small ions
        • INNER MEMBRANE: Has ATP synthase and electron carriers embedded
          • Electron carriers in ETC,s and are enzymes with cofactors that can accept and donate electrons
          • ATP synthase- protrudes from inner membrane to matrix and protons flow through down conc. gradient (chemiosmosis)
        • Protons accumulate in the intermembrane space and build up a proton gradient
      • OUTER MEMBRANE: Has protein carriers, channels and enzymes
      • MATRIX: Has enzymes for Link and Krebs, NAD, oxyloacetate, mito ribosomes and mito DNA (code for enzymes named)
    • Oxidative Phosphorylation and Chemiosmosis
      • Occurs on the inner mitochondrial membrane
      • Formation of ATP by adding phosphate to ADP in presence of O2 (final e- acceptor)
      • Electron carriers and ATPsynthase embedded in membrane
        • redNAD and redFAD reoxidised- H atoms released and split into H+ and e-
          • e- accepted by electron carrier and passed along electron transport chain
            • 4e- in ETC and 4H+ are accepted by O2 and produce 2H2O
          • H+ stay in matrix solution
            • As e- flows along ETC, energy released used by electron carriers to pump H+ into intermemebrane space
              • Oxidative Phosphorylation and Chemiosmosis
                • Occurs on the inner mitochondrial membrane
                • Formation of ATP by adding phosphate to ADP in presence of O2 (final e- acceptor)
                • Electron carriers and ATPsynthase embedded in membrane
                  • redNAD and redFAD reoxidised- H atoms released and split into H+ and e-
                    • e- accepted by electron carrier and passed along electron transport chain
                      • 4e- in ETC and 4H+ are accepted by O2 and produce 2H2O
                    • H+ stay in matrix solution
                      • As e- flows along ETC, energy released used by electron carriers to pump H+ into intermemebrane space
                  • H+ flow back into matrix through ATPsynthase, driving rotation part of the enzyme
                    • Enzyme phosphorylates ADP and produces ATP
          • H+ flow back into matrix through ATPsynthase, driving rotation part of the enzyme
            • Enzyme phosphorylates ADP and produces ATP
          • Evidence for Chemiosmosis
            • Visual proof of cristae
            • Proof that chemiosmosis provides energy to produce ATP
            • Research proves need of certain enzymes and the need for the intermembrane space (outer membrane removed =  no ATP)
            • pH of IMS lower than matrix + and potential difference more neg in matrix
          • Anaerobic respiration in mammals and yeast
            • Release of energy from substrates without oxygen- only uses Glycolysis
            • redNAD has to be reoxised (recycled) for glycolysis to continue
              • Lactate fermentation
                • In mammals during vigorous activity
                • Pyruvate is H+ acceptor (from redNAD)
                  • Becomes Lactate using Lactate dehydrogenase
                    • Carried in the blood to the liver- back to pyruvate/glucose when O2 present
                      • Reduction in pH lowers enzyme activity= muscle fatigue
                • redNAD  to NAD can now accept more H+ from TP
                  • Pyruvate is H+ acceptor (from redNAD)
                    • Becomes Lactate using Lactate dehydrogenase
                      • Carried in the blood to the liver- back to pyruvate/glucose when O2 present
                        • Reduction in pH lowers enzyme activity= muscle fatigue
              • Ethanol fermentation
                • In fungi e.g. yeast cells
                • Pyruvate molecule loses CO2 (decarboxylase) making Ethanal
                  • Ethanal accepts H atoms from redNAD- reduces to Ethanol
                    • redNAD reoxidised to NAD
          • Respiratory Substrates
            • A organic substance that can be used for respiration (aerobic)
            • The more H+ in a substrate, the more ATP produced and the more O2 needed
            • Lipids- Fatty adcids combine with CoA and taken to mito matrix
              • Split into Acetyl CoA- B-oxidation makes redNAD and redFAD
            • Proteins- When lack of substrates, can be hydrolysed to amino acids
              • Converted to Pyruvate, Acetate etc
            • Carbs- Mostly glucose, other monosaccharides broken down into glucose
          • the process whereby energy stored in complex organic molecules is used to make ATP

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