Metabolism: Energy Metabolism: Energy and Enzymesand Enzymes

By: Holly Davis and Diana BrizanBy: Holly Davis and Diana Brizan

Energy:Energy: the ability to do work or the ability to do work or bring about change. Develop, grow bring about change. Develop, grow and reproduce.and reproduce.

There are many different types of energyThere are many different types of energy KineticKinetic is energy of motion (a ball is energy of motion (a ball

rolling)rolling) Mechanical is also a ball rolling or Mechanical is also a ball rolling or

muscle contractingmuscle contracting Solar energy is energy from the sunSolar energy is energy from the sun PotentialPotential is stored energy (food we eat) is stored energy (food we eat) Chemical energy (organic molecules)Chemical energy (organic molecules)

Laws of ThermodynamicsLaws of Thermodynamics

1.1. The law of conservation of energy.The law of conservation of energy.Energy cannot be created or destroyed, Energy cannot be created or destroyed, but it can be changed from one form to but it can be changed from one form to another.another.

2. Second Law2. Second LawEnergy cannot be changed from one Energy cannot be changed from one form to another without a loss of usable form to another without a loss of usable energy.energy.

EntropyEntropy: measures relative amount of disorder or : measures relative amount of disorder or randomness.randomness.

Every process in cells increases total entropy, Every process in cells increases total entropy, making less energy available to do work in the making less energy available to do work in the future.future.

Eventually all usable forms of energy become heat. Eventually all usable forms of energy become heat. Heat cannot be converted to any other form of Heat cannot be converted to any other form of energy.energy.

Metabolic ReactionMetabolic Reaction

Metabolism - sum of all chemical reactions Metabolism - sum of all chemical reactions that occur in a cellthat occur in a cell

Reactants – substances that participate in Reactants – substances that participate in reactionreaction

Products – substances that are formed as a Products – substances that are formed as a result of reactionresult of reaction

A + B ABProduct A and BJoin to form the reactant AB

A spontaneous reaction increases total entropy.A spontaneous reaction increases total entropy. Free energy “G” – amount of energy still free after Free energy “G” – amount of energy still free after

a chemical reaction has taken place.a chemical reaction has taken place. ExergonicExergonic reactions – product has less free reactions – product has less free

energy then reactantsenergy then reactants EndergonicEndergonic reactions – product has more free reactions – product has more free

energy then reaction, they can only occur if there energy then reaction, they can only occur if there is an input of energy.is an input of energy.

Endergonic reaction

ATP (adenosine triphosphate) ATP (adenosine triphosphate) Carrier of energyCarrier of energy Common energy currency, Common energy currency,

can be used in many can be used in many different types of reactionsdifferent types of reactions

ATP is constantly being ATP is constantly being made from ADP (adenosine made from ADP (adenosine diphosphate) and diphosphate) and Phosphate, little energy is Phosphate, little energy is wastedwasted

blue – ribose (5 carbon sugar)Green - adenine (a nitrogenous base)Yellow – phosphate groups

Coupled Reaction : when the energy released from an exergonic reaction is used to drive an endergonic reaction

Metabolic Pathways & Metabolic Pathways & EnzymesEnzymes

Enzyme is a protein molecule that functions Enzyme is a protein molecule that functions as an organic catalyst to speed chemical as an organic catalyst to speed chemical reactionreaction

Reactants in enzymatic reaction are called Reactants in enzymatic reaction are called substrates for that enzymesubstrates for that enzyme

Reactions in cells occur Reactions in cells occur usually because they usually because they are part of a are part of a metabolic metabolic pathwaypathway, series of linked , series of linked reactions.reactions.

Enzyme Substrate ComplexEnzyme Substrate Complex

One part of the enzyme is called the active One part of the enzyme is called the active site, which complexes with the substrate.site, which complexes with the substrate.

Fit together like “key and lock”. Fit together like “key and lock”. Induced Fit Induced Fit ModelModel means that it undergoes slight means that it undergoes slight change for optimum fit.change for optimum fit.

Every reaction requires Every reaction requires

its specific enzymeits specific enzyme

Factors Affecting Enzymatic SpeedFactors Affecting Enzymatic Speed

Substrate ConcentrationSubstrate Concentration: Enzyme : Enzyme activity increases as activity increases as concentration increases. When all concentration increases. When all active sites filled, max rate, active sites filled, max rate, cannot increase any morecannot increase any more

Temperature and pHTemperature and pH::

Higher temperature increases Higher temperature increases enzyme activity. KMT, higher enzyme activity. KMT, higher collision between enzyme and collision between enzyme and substrate. Too hot becomes substrate. Too hot becomes denatured. denatured.

At optimal pH the reaction is At optimal pH the reaction is highest. Extreme conditions of pH highest. Extreme conditions of pH also denatures the enzymealso denatures the enzyme

Enzyme ConcentrationEnzyme Concentration: If : If there are too many there are too many enzymes present they enzymes present they can get in the way. Only can get in the way. Only certain enzymes work for certain enzymes work for certain substrates.certain substrates.

Enzyme InhibitionEnzyme Inhibition: when : when an active enzyme is an active enzyme is prevented from prevented from combining with its combining with its substrate, eg. poisons.substrate, eg. poisons.

Oxidation-ReductionOxidation-Reduction

Oxidation – the loss of electronsOxidation – the loss of electrons Reduction – gain of electronsReduction – gain of electrons Example: Na + Cl Example: Na + Cl NaCl NaCl

sodium has been oxidized, chlorine has been reducedsodium has been oxidized, chlorine has been reduced When oxidation and reduction go hand in hand it is When oxidation and reduction go hand in hand it is

called a called a redox reactionredox reaction

This is an example of a spontaneous redox reaction. When zinc metal is placed in a solution of copper sulfate, the copper is reduced and appears as a black coating on the zinc.

Photosynthesis and cellular respiration permit Photosynthesis and cellular respiration permit

a a Flow of Energy Flow of Energy from the sun from the sun through all living thingsthrough all living things

Photosynthesis:Photosynthesis:energy + carbon dioxcide + water energy + carbon dioxcide + water

glucose + oxygen glucose + oxygenChloroplasts capture solar energy Chloroplasts capture solar energy

and convert it into ATPand convert it into ATP

Cellular Respiration:Cellular Respiration:Glucose + oxygen Glucose + oxygen carbon carbon

dioxcide + water + energydioxcide + water + energyWhen ATP is used up as an When ATP is used up as an

energy source, all useable energy source, all useable energy is converted into heatenergy is converted into heat

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04chemrxn/sponoxred.jpg04chemrxn/sponoxred.jpg