Metabolism & Energy Transfer

Bio 391Sections 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!ExergonicExergonic 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 conditions1. pH2. Temperature (human body = 37C)3. Concentration how many are there?

E or S4. Inhibitors other substances can interfere5. 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

MoleculesMETABOLISM: 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!