Metabolism & Energy Transfer Bio 391 Sections 2.6 – 2.8

Learning Goals Understand that Reactions can build up or break down and involve gain & loss – Dehydration Synthesis vs. Hydrolysis – Oxidation-Reduction – Anabolism vs. Catabolism Enzymes speed up reactions ATP is the energy currency of living organisms

Reaction in Living Things All living things carry out endergonic reactions (reactions that store energy) First they need to get the energy from somewhere! Exergonic Exergonic sources of energy (reactions release energy) Sun Chemicals food Problem: These reactions all need to occur quickly in order to keep up with the speed of life! Solution: Catalysts  substance that speeds up the rate of chemical reactions

Enzymes lower Activation Energy

Enzymes are…  proteins that lower the activation energy required and allow reactions to happen at the normal temperature of cells. SPECIFIC  only works on one particular reaction REUSABLE  over and over again for that reaction NAMED after their substrate (the reactant that the enzyme helps) – ends in –ASE S binds to E at the ACTIVE SITE Coenzymes are non-protein helper molecules that sometimes assist enzymes with their job.

Enzyme action Enzyme action is very sensitive to environmental conditions 1. pH 2. Temperature (human body = 37C) 3. Concentration  how many are there? E or S 4. Inhibitors  other substances can interfere 5. Time  How long do the compounds get to interact?

Competitive v. Noncompetitive INHIBITION

CATABOLISM DIGESTION EXOTHERMIC RELEASE E BREAK BONDS CELL RESPIRATION DECOMPOSITION ANABOLISM DEHYDRATION SYNTHESIS ENDOTHERMIC STORE E MAKE BONDS REDUCTION Small Molecules Big Molecules METABOLISM: all the chemical activities & changes that take place in a cell or organism

Oxidation & Reduction In addition to discussing if ENERGY is being stored or released in a reaction, – Endergonic v. exergonic you can focus on whether ELECTRONS are being gained or lost – think : is the molecule getting bigger or smaller? – If it’s gaining atoms, it’s typically gaining e- OIL RIG…rEducE

ATP When bonds are broken, electrons are removed and transferred to a “storage” molecule to be held and transferred when needed. ATP: Adenosine triphosphate Energy Transfer Molecule GTP and UTP 7.3 kcal

In one minute a working muscle cell uses 10,000,000 ATP molecules. That is the cell's entire supply, so ADP must be recycled into ATP. Even resting in bed, you use 20 kg of ATP every 24 hours!