ATP Production and cellular respiration

• There are three types of respiration: external, internal, and cellular.
• ATP stands for Adenosine Triphosphate and is the cells energy molecule, fuelling most reactions and activity in cells.
• An adult human female requires 6300 – 7500 kJ metabolic energy per day, which corresponds to the amount of free energy released from the breakdown of 200 moles ATP per day.
• One mole of ATP has 6.0221 x 1023 molecules of ATP and is generally less than 0.1 mole in the body at any point.
• The weight of 200 moles of ATP is 200 x 507.18 g, which equals 101436 g or 101.44 kg.
• Aerobic respiration is the process that occurs when oxygen is present, while anaerobic respiration is the process that occurs when oxygen is not present.
• Metabolism is the process of cellular respiration and outlines the pathways involved: glycolysis, Citric acid cycle, electron transport chain.
• Oxygen is important for cellular respiration as it is used in the process of making ATP in the mitochondria of a cell.
• External respiration involves pulmonary ventilation, alveoli, and respiratory membrane.
• Internal respiration involves oxygen and carbon dioxide exchange at tissue beds.
• Cellular respiration involves making ATP in the mitochondria of a cell.
• Biochemical respiration is the breakdown of nutrients to produce ATP.
• Cellular respiration is the breakdown of nutrients to produce ATP.
• ATP stands for Adenosine triphosphate and serves as an energy currency in cells.
• Hydrolysis of ATP releases a relatively large amount of free energy.
• ATP (Adenosine triphosphate) is a molecule made from ADP and Pi by energy released from thermodynamically favourable reactions.
• The stored energy is then used for energy-requiring processes such as active transport and synthesis of macromolecules.
• The energy is released by the hydrolysis of the last phosphate group forming ADP plus Pi.
• ATP can be made aerobically or anaerobically.
• Mostly made in the Krebs cycle (mitochondrion) although some during glycolysis (cytoplasm).
• A minor portion of ATP is formed by substrate level phosphorylation of ADP.
• The major portion of ATP is formed by the oxidative phosphorylation of ADP within the mitochondria.
• Substrate level phosphorylation is the addition of a phosphate group to a molecule.
• Oxidative phosphorylation is the production of ATP using the electron transport chain and chemiosmosis.
• Oxygen is essential in oxidative phosphorylation.
• Glycolysis breaks down glucose to smaller molecules.
• The Krebs cycle/ Citric acid cycle/ Tricarboxylic cycle takes the smaller molecules and systematically changes their structure.
• Oxidative phosphorylation (oxidise and add phosphate group) involves multiple reactions that ultimately add a phosphate onto ADP so making ATP.
• Glycolysis has 10 steps in the reaction pathway, one molecule of glucose (6C) → 2 molecules of pyruvate (2 x3C), and requires 2 molecules of ATP to be used up and 4 molecules of ATP to be produced, resulting in a net production of 2 ATP and 2 molecules of NADH (from the catabolism of 1 molecule of glucose).
• The end product of glycolysis is pyruvate.
• An adult human female requires 6300 – 7500 kJ metabolic energy per day, which corresponds to the amount of free energy released from the breakdown of 200 moles ATP per day.
• One mole of ATP has 6.0221 x 1023 molecules of ATP and is generally less than 0.1 mole in the body at any point.
• Pyruvate oxidation links glycolysis and the citric acid cycle, converting pyruvate to acetyl which is linked to Coenzyme A (larger molecule), occurring within the mitochondrial matrix, yielding one molecule of NADH, and acetyl-CoA (final product) enters the citric acid cycle.
• The Citric acid cycle, also known as Tricarboxylic acid cycle (TCA) or Kreb’s cycle, occurs in the mitochondrial matrix, using three molecules of NADH, one molecule of FADH2 and one molecule of GTP, producing three molecules of NADH, one molecule of FADH2 and one molecule of GTP, with GTP being similar to ATP and FADH2 being similar to NADH.
• The first step of the citric acid cycle forms citrate from oxaloacetate and acetyl-CoA, and the last step of the citric acid cycle produces more oxaloacetate to combine with more acetyl-CoA, releasing energy in the process.
• The energy released in the citric acid cycle is ‘stored’ in the high energy molecules NADH, GTP, FADH2, which enter the next pathway.
• Oxidative phosphorylation occurs ACROSS the mitochondrial inner membrane, with two linked stages: the Electron Transport Chain proteins create a proton (H+) gradient across the membrane, and Chemiosmosis is ATP synthase enzyme using the proton gradient energy to make ATP.
• The Electron Transport Chain consists of four protein complexes within or on the inner mitochondrial membrane, with the high energy molecules feeding electrons into these complexes, electrons flowing from high energy state to low energy state to eventually bind to oxygen 2 e- + ½O2 + 2 H+ → H2O, and the energy released is used to push protons across the membrane.
• The respiratory chain is comprised of four different classes of molecule: Cytochromes, Iron-sulphur proteins, Flavoproteins, and Quinones, with Cytochromes all containing a haem group, Iron-sulphur proteins having iron bound to cysteine, Flavoproteins being enzymes that contain FMN or FAD, and Quinones being lipid electron carriers that can easily move in the bilayer of the inner membrane.
• The weight of 200 moles of ATP is 200 x 507.18 g, which equals 101436 g or 101.44 kg.