Metabolism and Energy

Metabolismand

EnergyChapters 8

Metabolism and Energy

Metabolism Catabolism Anabolism

Bioenergetics Energy

Kinetic Heat/Thermal Light Energy Potential Chemical

Organisms are energy transformers!


Metabolism Metabolic pathway begins with a

specific molecule, which is then altered in a series of defined steps leading to a specific product

Each step is catalyzed by a specific enzyme



Metabolism Catabolism

Energy released (helps to drive anabolic pathways).

Ex: cellular respiration sugar put in to the body is broken

down to do work in the cell (movement, active transport, etc).




sometimes called biosynthetic pathways- Ex: synthesis of a protein from

amino acids. Energy required/absorbed.




Bioenergetics the study of how energy flows through

living systems.


Metabolism and Energy Metabolism

Catabolism Anabolism

Bioenergetics Energy

the capacity to cause change. Some forms of energy can be used to do

work- or move matter against opposing forces Ex: (friction and gravity) Ability to rearrange a collection of

matter



Energy Kinetic

Relative motion of objects moving objects can perform

work by imparting motion to other matter.

Ex: Moving water through a dam turns turbines, moving bowling ball knocks over pins



Energy Kinetic

Heat/Thermal comes from the movement of

atoms or molecules associated with kinetic energy



Energy Kinetic

Heat/Thermal Light Energy

Type of energy that can be harnessed to perform work

Ex. Powering Photosynthesis



Kinetic Heat/Thermal Light Energy

Potential Non-kinetic energy because of location or

structure, height, chemical bonds, etc.


Metabolism and Energy Kinetic

Heat/Thermal Light Energy

Potential Chemical

the potential energy available for release by a reaction.

Ex: Glucose is high in chemical energy and the process of glycolysis breaks it down. As bonds are broken, energy is released, but bonds also reform to make new molecules, thus it uses some energy.




All original energy comes from light. (photosynthesis-

primary producer- consumer- who changes

it from chemical to kinetic and releases

thermal.

Thermodynamics What is Thermodynamics?

Thermodynamics The energy transformations that occur in a

collection of matter

Thermodynamics Thermodynamics

System vs. Surroundings Isolated System vs. Open System

First Law of Thermodynamics

Thermodynamics Two Laws of Thermodynamics govern

energy exchange: First Law of Thermodynamics Second Law of Thermodynamics

Thermodynamics Two Laws of Thermodynamics govern

energy exchange: First Law of Thermodynamics

energy cannot be created or destroy- Only transferred or transformed Known as Principle of conservation of

energy

Thermodynamics Second Law of Thermodynamics

During energy transfer, some energy become unusable energy (unavailable to do work)

Entropy (S) – Measure of disorder or randomness

Thermodynamics So, What is the Second Law of

Thermodynamics? Every energy transfer or transformation

increases the entropy of the universe

Thermodynamics Spontaneous (Energetically Favorable) vs.

Nonspontaneous Processes Leads to the second way we state the 2nd Law

of Thermodynamics: For a process to occur spontaneously, it must

increase the entropy of the universe

Think-Pair-Share How does the second law of

thermodynamics help explain the diffusion of a substance across a membrane?

If you place a teaspoon of sugar in the bottom of a glass of water, it will dissolve completely over time. Left longer, eventually the water will disappear and the sugar crystals will reappear. Explain these observations in terms of entropy.

Gibbs Free Energy Free Energy

Portion of system’s energy that can perform work when temp and pressure are uniform throughout system

ΔG = free energy of a system -ΔG = spontaneous reaction +ΔG = nonspontaneous reaction ΔG = 0 = Dead Cell (can do no work)

ΔG = ΔH – TΔSΔG = ΔGfinal – ΔGinitial

Enthalpy

Gibbs Free EnergyΔG = ΔH – TΔS

ΔG = ΔGfinal – ΔGinitial

ΔH = he change in the system’s enthalpy What is enthalpy?

Total energy

ΔS = change in system’s entropy T = absolute Temperature in Kelvin

Gibbs Free EnergyΔG = ΔH – TΔS

ΔG = ΔGfinal – ΔGinitial

Can think of this as difference in final state and initial state

Gibbs Free Energy Endergonic vs. Exergonic Reactions +ΔG -ΔG

Non-Spontaneous Spontaneous

Gibbs Free Energy Reactions in isolates system eventually reach

equilibrium and then cannot do work Metabolism reactions are reversible and

eventually will reach equilibrium Living cell is not in equilibrium Some reactions are constantly pulled in one

direction and this keeps them from reaching equilibrium

Warm Up Exercise Glow in the dark necklaces are snapped in

a way that allows two chemicals to mix and they glow. Is this an endergonic or exergonic reaction? Explain.

In simple diffusion, H+ ions move to an equal concentration on both sides of a cell membrane. In cotransport, H+ ions are pumped across a membrane to create a concentration gradient. Which situation allows the H+ ions to perform work in the system?

ATP and Cellular Work

Three Types of Work Chemical Transport Mechanical

Energy Coupling Phosphorylated

Intermediate

Why is ATP such a good energy

molecule? What is ATP?

Contains ribose sugar, nitrogenous base adenine, and chain of 3 phosphate groups bonded to it.

Bonds can be broken by hydrolysis

Why is ATP such a good energy

molecule? When bond is broken , a molecule of

inorganic phosphate leaves the ATP It become adenosine diphosphate (ADP)

Is Hydrolysis of ATP endergonic and

exergonic? Anabolic or catabolic?

Does it release -7.3 kcal / mol in the cell?

ATP Hydrolysis kh

ATP and Cellular Work

ATP Cycle The body regenerates 10 million

molecules of ATP per second per cell!

Enzymes Enzymes- biological catalyst Substrates – reactants that bind to the

enzyme, usually in the active site

Enzymes Activation Energy (EA)

the energy required to get a reaction started.

Many times this energy is absorbed as thermal energy from the environment

Many times room temperature may be enough, but most reactants need more energy than that to get started. AKA = free energy of activation

Enzymes Activation Energy (EA)

the energy required to get a reaction started.

How does heat effect an enzyme?

Heat speeds a reaction by allowing reactants to attain the transition state more often

This solution is inappropriate for biological systems because it would denature proteins and kill cells.

Additionally, it would speed up all reactions, not just those that are needed.

Enzymes Enzymes catalyze reactions by lowering

the activation energy.

Enzymes Enzyme + Substrate = Enzyme-Substrate

Complex

Enzyme Enzyme- Enzyme + Substrate +Substrate(s) Complex Product(s)

Enzymes Active Site

pocket or groove on the surface of the enzyme where the substrate binds and catalysis occurs.

Enzymes Induced Fit

When the substrate enters the active site, it forms weak bonds with the enzyme, inducing a change in the shape of the protein. This change allows additional weak bond (ie: hydrogen bonds) to form, causing the active site to fit around the substrate snugly-

Effects of Environment

Changes in the environment of the enzyme can cause inefficiencies or denaturation of the enzyme: Temperature pH Concentration of Enzyme Concentration of Substrate

Enzymes Cofactors

nonprotein components that help in catalytic activity.

Usually bound to enzyme (sometimes permanently, sometimes loosely)

Coenzyme If cofactor is organic Many vitamins are important because they

are coenzymes or make up coenzymes

Enzyme Action Competitive Inhibitors

Resembles normal substrate molecule Reduce productivity of enzyme by blocking

substrates from entering active sites

Enzyme Action Noncompetitive Inhibitors

Don’t directly compete with substrate Impede enzymatic reactions by binding to

another part of the enzyme

Allosteric Regulation

Allosteric Regulation Term used to describe any case in which a

protein’s function at one site is affected by the binding of a regulatory molecule to a separate site

Can be inhibition or stimulation Generally constructed from two or more

subunits

Allosteric Site regulatory site Both activators and inhibitors can bind to

these sites: Activator stabilizes functional active site Inhibitors stabilizes inactive form

Shape change in one subunit affects shape of other subunit

Cooperativity A different type of allosteric activation in

which a substrate binds to an active site stimulating the catallytic powers of a multisubunit enzyme by affecting other active sites

Cooperativity Amplifies the response of enzymes to substrates An induced fit in one subunit can trigger the

same favorable shape change in other subunits

Feedback Inhibition Metabolic pathway switched off by the

inhibitory binding of its end product to an enzyme that acts early in the pathway

Feedback Inhibition

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Metabolism and Energy