Metabolism Flashcards
Describe the second law of thermodynamics
The amount of disorder (entropy) in the universe always increases with any change that occurs, and at the same time the energy that can do useful work decreases (lost as heat)
Describe the first law of thermodynamics
Energy can be neither created nor destroyed, it can only be transformed from one form to another
When does entropy increase in chemical reactions?
When solids become liquids or gases, when fewer reactant molecules from a greater number of product molecules, when complex molecules are broken down into simpler subunits, when solutes move from diffusion
Describe activation energy
The amount of energy needed to strain and break the reactant bonds
Describe transition state
A temporary condition in which the bonds within the reactants are breaking and bonds between the products are forming. Energy is released when product bonds are formed
Describe an exothermic reaction
If more energy is released during bond formation then was absorbed during bond breaking, there is a net energy output. It occurs spontaneously, therefore it is favoured because it increases entropy. Its products contain less energy than the reactants, therefore they are more stable. And usable energy is released (decrease in free energy available)
Show an annotated diagram of an exothermic reaction
Describe an endothermic reaction
If the amount of energy absorbed from breaking reactant bonds is greater than the energy released in the formation of products, the result is a net absorption of energy. It does not occur spontaneously and is not favoured because they involve a decrease in entropy (second law of thermodynamics). Its products contain more energy than the reactants. And it requires an input of energy (ex. ATP needed to drive reactions)
Show an annotated diagram for an endothermic reaction
Describe enzymes
Biological catalysts, proteins that regulate all biological processes
What determines the speed of chemical reactions?
The amount of activation energy needed, the concentration and effectiveness of the catalyst
How do enzymes work?
The shape of the globular protein determines the function, they stress chemical bonds, lower the activation energy barrier
Show an annotated endergonic energy diagram with the addition of enzymes
Show an annotated exergonic energy diagram with the addition of enzymes
Describe how enzymes work
Surface depressions are active sites and represent the location of catalysis. The substrate (reactant molecule on which the enzyme acts) must fit the active site exactly. The enzyme stresses the chemical bond, thereby lowering its activation energy barrier
What factors affect enzyme activity?
Temperature, pH, and enzyme and substrate concentration They disrupt the bonds of the protein (enzyme) and denature it, changing its shape and thus, its function
Describe enzymatic allosteric sites
Receptor sites some distance away from the active site that binds substances to the enzyme that may either inhibit or stimulate an enzyme’s activity
How is enzyme activity regulated?
Inhibitors decrease the enzyme activity. Competitive inhibitors dont involve the allosteric site and are substances that compete with the substrate for an enzyme active site and block the substrate from binding
Describe noncompetitive inhibitors
Substances that attach to a binding site on an enzyme other than the active site (pricking the factory worker metaphor). This causes a change in the enzymes shape, therefore regular substrates will not fit
Describe an allosteric inhibitor
A substance that binds to an allosteric site on an enzyme, altering its active site and stabilizing the inactive form of the enzyme. This prevents the substrate from binding to it
Describe enzymatic activators
Increases the enzymes activity, because an activator binds to an allosteric site which stabilizes the protein conformation and keeps all of the active sites available to their substrates. Both inhibitors and activators work because of allosteric changes of the enzyme as a result of the binding of a non-substrate molecule to the enzyme. Activator “effector” stabilizes or activates the enzyme, allowing it to bind to the substrate
Define metabolism
The total amount of all anabolic and catabolic reactions in a cell or organism
Define kinetic energy
The energy of moving particles or objects (heat contracting)
Define potential energy
Stored energy; the energy of position (chemical bonds, the attraction of electrons to protons, etc.)
