Energy and Metabolism KEY WORDS: Energy Free Energy (ΔG) Potential energy Kinetic energy Enzyme Substrate Activation energy Exergonic reaction Endergonic reaction Catalyst ATP/ ADP

Energy The capacity to do work Move matter

Types of energy Question: __________ is an example of kinetic energy, and __________ is an example of potential energy. 1.Fire; a piece of wood 2.A loaded gun; a flying bullet 3.A rock on top of a hill; a rock rolling down the hill 4.None of these are correct. 5.All of these are correct. Kinetic Potential

Chemical Energy Stored in chemical bonds -high energy electrons Some molecules store a lot of energy Some molecules store much less Carbos, lipids Carbon dioxide, water

Chemical Energy Energy can be transferred/transformed Sugar + oxygen  carbon dioxide + water + heat C 6 H 12 O 6 + O 2  CO 2 + H 2 O + Energy

First Law of Thermodynamics: Energy: neither created nor destroyed Converted from one form to another Exchanged between substances

All exchanges of energy increase the entropy of the universe Entropy: Disorder or randomness of a system Heat is most disorganized form of energy Reactions that ↑ entropy happen spontaneously & release energy Second Law of Thermodynamics:

Two laws of thermodynamics

Energy Transformed

Exergonic Reactions Release energy “Spontaneous” Usually breakdown of complex molecules

Endergonic Reactions Not “Spontaneous” Usually involve synthesis of complex molecules 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Require energy + Energy

1.CO 2 and H 2 O Glucose 2.Amino acids Proteins 3.TriglyceridesFatty acids 4.Ions moving across membrane from an area of high concentration to an area of low concentration. Question: Which of the following reactions is endergonic?

Question: Which of the following reactions releases energy? 1.CO 2 and H 2 O Glucose 2.Amino acids Proteins 3.TriglyceridesFatty acids 4.Ions moving across membrane from an area of high concentration to an area of low concentration.

Coupled Reactions glucose CO 2 + H 2 O Energy Exergonic Endergonic Energy Amino acids Protein Exergonic provides energy for the endergonic

Living organisms Metabolism All chemical reactions in an organism Anabolism Catabolism

Living organisms Capture energy to drive chemical reactions. Energy Energy Convert “raw” energy into usable form Sunlight, food ATP

The structure and hydrolysis of ATP

ATP: the Cell’s Rechargeable Battery ATP energy ADP charged batterydead battery This energy can then be used to run an energy requiring reaction.

The ATP cycle

1.is never lost or gained, but is only transformed 2.always requires an ultimate source such as the sun 3.can never be gained, but can be lost 4.can never really be harnessed 5.can never be transformed According to the first law of thermodynamics, energy

1.Some energy is lost, but other energy is created. 2.Some energy must come from the sun. 3.Some energy is transformed into heat. 4.Energy is gained for future use. 5.Some energy is permanently and completely destroyed. Each time there is a chemical reaction, some energy is exchanged. According to the second law of thermodynamics, with each exchange

1.mechanical energy 2.heat 3.complex carbohydrates 4.chemical bond energy 5.amino acids ATP stores energy in the form of

The complexity of metabolism

Equation: Gibb’s Free Energy ΔG = ΔH – TΔS Energy available for work All energy Energy NOT available for work

The relationship of free energy to stability, work capacity, and spontaneous change

Energy changes in exergonic and endergonic reactions

Energy profile of an exergonic reaction

Disequilibrium and work in closed and open systems

Is ΔG for an exergonic reaction positive or negative?

What is the difference between: Anabolism Catabolism Metabolism

From an energy perspective, when is equilibrium reached?

Enzymes KEY WORDS: Enzyme Activation energy Catalyst Substrate Active site Induced fit Coenzyme Allosteric site Competitive inhibitor Noncompetitive inhibitor Feedback inhibition

Enzymes and Shape Active Site Induced fit: “Handshake” between substrate and enzyme

Activation Energy Net Energy Released

Enzymes Proteins that speed up chemical reactions (catalysts) Lower activation energy for a reaction

S = Substrates (reactants) enter reaction. P = Product (what you get at the end) result E = Enzymes mediate specific steps sucrase sucrose + H 2 O glucose + fructose E + S ES E + P Enzyme reactions can be simplified as:

The catalytic cycle of an enzyme

Enzymes Key Points: Catalyze reactions Don’t change reactions Same net release/use of energy Enzymes are not changed by reaction Each enzyme catalyzes a specific chemical reaction

Enzymes lower the barrier of activation energy

1.lowering the temperature 2.lowering the pressure 3.using an enzyme 4.changing the amount of the reactants 5.supplying ATP Which of the following will lower the activation energy of a reaction in a cell?

1.lowering the temperature 2.lowering the pressure 3.using an enzyme 4.changing the amount of the reactants 5.supplying ATP Which of the following will lower the activation energy of a reaction in a cell?

1.accelerate specific chemical reactions 2.are not chemically altered by binding with a substrate 3.lower the activation energy of specific chemical reactions 4.all of the above 5.a and c only Enzymes

4 Things that Affect Enzyme Activity 1.Substrate concentration 2.Enzyme concentration 3.pH 4.Temperature Shape of enzyme (Protein denatured)

Environmental factors affecting enzyme activity

Enzyme Regulation Enzymes can be turned on and off Regulated by other molecules in the cell Examples: –Allosteric regulation –Feedback inhibition –Inhibitors

Inhibition of enzyme activity

Allosteric regulation of enzyme activity

Feedback inhibition

If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is: a)Add more enzyme b)Heat the solution c)Add more substrate d)Add an allosteric inhibitor e)Add a noncompetitive inhibitor

An enzyme accelerates a metabolic reaction by a)Altering the overall free energy change for the reaction b)Making an endergonic reaction occur spontaneously c)Lowering the activation energy d)Pushing the reaction away from equilibrium e)Making the substrate molecule more stable

Some bacteria are metabolically active in hot springs because a)They are able to maintain a cooler internal temperature b)High temperature facilitates active metabolism w/o need of catalysis c)Enzymes have high optimal temperatures d)Enzymes are insensitive to temperature

1.consists of a series of chemical reactions 2.uses a number of enzymes 3.involves the modification of a series of substrates 4.proceeds by means of each enzyme leaving a succeeding reaction to a different enzyme 5.all of the above Glycolysis is a metabolic pathway that helps living things extract energy from food. From this we know that glycolysis