M ETABOLISM AND E NZYMES Chapter 8

W HAT IS M ETABOLISM ? The totality of an organism’s chemical reactions Essentially it is energy in an organism or the change of one type of energy to another. Metabolic Pathway is the way that molecules are built or broken down. It may have many steps depending on the building or breaking. Catabolic Pathway explains how things are broken down to simple molecules Anabolic pathways explain how things are created from simple molecules

M ETABOLIC P ATHWAYS AND E NERGY All of the previous reactions require ENERGY There are several forms of energy you need to know: Kinetic Energy Heat/thermal energy Potential energy Chemical energy

R EACTIONS, E NERGY AND M ETABOLISM Free Energy: the portion of a system’s energy that can perform work when the temperature and pressure are the same throughout the system. (Think of living systems!) Exergonic reactions: Release free energy (releasing energy) Endergonic reactions: absorb free energy (storage of energy)

ATP Adenosine Triphosphate is the name given to “energy” in the body. It is a structure that stores energy between phosphate bonds. ATP has energy stored When ATP is reduced to ADP energy for the body is released

W HAT ABOUT ENZYMES? Enzymes are catalytic proteins Catalyst is an agent that speeds up the rate of reaction If you add an enzyme to a reaction it will reduce the amount of time that it takes for the reaction to occur. Enzymes also have a variety of other functions.

H OW DO ENZYMES WORK ? The way that enzymes work is often referred to as a lock and key. Enzymes are able to take the substrate (the things that are reacting) and bind to it creating the enzyme-substrate complex. The enzyme will only bond to the substrates for which it was formed!! Once the complex is created it will become apparent that only certain parts of the enzyme and substrate will touch this is the active site

W HAT ELSE CAN E NZYMES DO ? Lower activation Energy Activation energy is the amount of energy required to start a reaction When an enzyme is present that energy amount is reduced significantly

W HAT C AN C HANGE OR E FFECT AN E NZYME Obviously things can change. To change an enzyme you would alter the temperature and or pH. Both of these factors must be at the correct level for conditions to be conducive for the reaction to occur. If these things are changed to much they will start to denature (break-down) the enzyme and start to make it non-functional.

W HAT ELSE CAN E FFECT THE E NZYME ACTIVITY ? The removal of co-factors (enzyme helpers) you know them as coenzymes Inhibitors They try to keep the enzyme from completing the task at hand.

I NHIBITORS Competitive Reduce the ability of enzymes to produce a product by blocking the active site Noncompetitive Do not directly compete with the substrate to bind to the enzyme at the active site

E NZYMES AND M ETABOLISM Allosteric regulation is when a proteins function or shape at one site is affected by a molecule at a separate site this helps inhibit other reactions from occurring when they are not necessary Feedback inhibition is when a metabolic pathway is turned off by a binding enzyme.