Metabolic Pathways Study Notes

How does a cell extract energy and reducing power from its environment? How does a cell synthesize building blocks of its macromolecules and then the macromolecules themselves?

Metabolic pathways

ATP (Adenosine triphosphate)

<p>Catabolism</p> Signup and view all the answers

<p>Anabolism</p> Signup and view all the answers

<p>Individual reactions are specific, provided by the specificity of enzymes. The entire set of reactions must be thermodynamically favourable.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>The concentrations of the reactants and products at equilibrium.</p> Signup and view all the answers

<p>ΔGo = -RT lnKeq</p> Signup and view all the answers

<p>Maintaining out of equilibrium [Reactant]:[Product] ratios Coupling an unfavorable rx (+ΔG) to a favorable rx (-ΔG)</p> Signup and view all the answers

<p>ΔG = ΔGo + RT lnQ</p> Signup and view all the answers

<p>Keq is a constant that describes the system at equilibrium, while Q is used to describe the system potentially not at equilibrium and reflects the actual concentrations of products and reactants.</p> Signup and view all the answers

<p>The standard free energy change (ΔGo) for this reaction is +1.7 kJ/mol. This positive value indicates that the conversion of glucose-6-phosphate to fructose-6-phosphate is thermodynamically unfavorable (nonspontaneous).</p> Signup and view all the answers

<p>Biological systems maintain the directionality of this reaction by maintaining the concentrations of reactants and products out of equilibrium. Specifically, the concentration of glucose-6-phosphate is kept much higher than the concentration of fructose-6-phosphate in the cell.</p> Signup and view all the answers

<p>Maintaining out of equilibrium concentrations of reactants/products Coupling the reaction to ATP hydrolysis</p> Signup and view all the answers

<p>ATP + H2O → ADP + Pi (inorganic phosphate)</p> Signup and view all the answers

<p>-30.5 kJ/mol</p> Signup and view all the answers

<p>Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, Ligases</p> Signup and view all the answers

<p>Oxidation-reduction reactions</p> Signup and view all the answers

<p>Transfer of molecular groups from one molecule to another</p> Signup and view all the answers

<p>Cleavage of bonds by the addition of water</p> Signup and view all the answers

<p>Rearrangement of atoms within a molecule</p> Signup and view all the answers

<p>Joining of two molecules by the formation of a new bond</p> Signup and view all the answers

<ol> <li>Phosphorylation of glucose to glucose-6-phosphate</li> <li>Isomerization of glucose-6-phosphate to fructose-6-phosphate</li> <li>Phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate</li> <li>Cleavage of fructose-1,6-bisphosphate into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate</li> <li>Isomerization of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate</li> <li>Oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate (and NADH production)</li> <li>Transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP, forming ATP (substrate-level phosphorylation)</li> <li>Isomerization of 3-phosphoglycerate to 2-phosphoglycerate</li> <li>Dehydration of 2-phosphoglycerate to phosphoenolpyruvate, a molecule with a very high phosphoryl transfer potential</li> <li>Transfer of a phosphate group from phosphoenolpyruvate to ADP, forming ATP (substrate-level phosphorylation)</li> </ol> Signup and view all the answers

<p>2 mol ATP and 2 mol NADH</p> Signup and view all the answers

<p>Aerobic respiration Anaerobic respiration Fermentation</p> Signup and view all the answers

<p>Oxygen (O2)</p> Signup and view all the answers

<p>Carbon dioxide (CO2) and water (H2O)</p> Signup and view all the answers

<p>Pyruvate</p> Signup and view all the answers

<p>Lactic acid or ethanol</p> Signup and view all the answers

<p>Ribonucleotide (RNA synthesis) Precursor of dATP (DNA synthesis) Precursor for coA Precursor of NAD+ Precursor of FAD</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>Complex I (NADH-Q reductase) Complex II (Succinate dehydrogenase) Complex III (Q-cytochrome c reductase) Complex IV (Cytochrome c oxidase)</p> Signup and view all the answers

<p>The proton motive force is an electrochemical gradient across a membrane, generated by the uneven distribution of protons across the membrane.</p> Signup and view all the answers

<p>ATP synthase is a molecular motor that uses the energy of the proton motive force to synthesize ATP from ADP and Pi.</p> Signup and view all the answers

<p>The mechanism by which ATP synthesis occurs is known as the Chemiosmotic Theory. This theory states that the energy of electron transfer through the electron transport chain is first converted into a proton gradient across the inner mitochondrial membrane, known as the proton motive force. This proton gradient is then used by ATP synthase to generate ATP from ADP and Pi.</p> Signup and view all the answers

<p>Oxidative phosphorylation is the process by which ATP is synthesized using the energy of the proton motive force, which is generated by the electron transport chain. Substrate-level phosphorylation is the process by which ATP is synthesized directly from a high-energy phosphate compound, such as phosphoenolpyruvate or 1,3-bisphosphoglycerate.</p> Signup and view all the answers

<p>Uncouplers and electron flow inhibitors</p> Signup and view all the answers

<p>Uncouplers dissipate the proton motive force, which is the electrochemical gradient across the mitochondrial membrane that is used to generate ATP.</p> Signup and view all the answers

<p>Electron flow inhibitors block the flow of electrons through the electron transport chain, preventing the generation of ATP.</p> Signup and view all the answers

<p>FAD</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>ATP synthesis, Heat Production, Active Transport, Flagellar Rotation</p> Signup and view all the answers

<p>ATP synthase is a complex protein composed of two main parts: F0 and F1. The F0 subunit is embedded in the mitochondrial membrane and contains a ring of c subunits. The F1 subunit is located in the mitochondrial matrix and is composed of α, β, γ, δ, and ε subunits. The F0 and F1 subunits are connected by a central stalk, which is attached to the γ subunit. The γ subunit rotates as protons flow through the F0 c ring. This rotation drives conformational changes in the β subunits of the F1 subunit, which in turn drives the synthesis of ATP from ADP and Pi.</p> Signup and view all the answers

<p>The c ring is a component of the F0 subunit of ATP synthase. It is composed of multiple c subunits that are arranged in a ring. As protons flow across the inner mitochondrial membrane, they bind to the c ring, causing it to rotate. This rotation drives the γ subunit, which in turn drives the synthesis of ATP from ADP and Pi.</p> Signup and view all the answers

<p>The energy from electron transport is first used to generate a proton gradient across the inner mitochondrial membrane, known as the proton motive force. This proton gradient is then used by ATP synthase, a molecular motor, to synthesize ATP from ADP and Pi.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>The rotation of bacterial flagella is driven by a motor that is powered by the proton motive force. This force is generated by the difference in proton concentration across the bacterial membrane. Think of the motor as a water wheel with a generator. As protons flow through the motor, they turn the wheel, which in turn drives the rotation of the flagellum. The flagellum allows bacteria to move towards nutrients, away from harmful substances, and to colonize new environments. The proton motive force is a crucial source of energy for bacterial motility.</p> Signup and view all the answers