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Metabolismand
EnergyChapters 8
Metabolism and Energy
Metabolism Catabolism
Anabolism
Bioenergetics
Energy Kinetic
Heat/Thermal
Light Energy
Potential
Chemical
Organisms are energy transformers!
Metabolism and Energy
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
Organisms are energy transformers!
Metabolism and Energy
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).
Organisms are energy transformers!
Metabolism and Energy
Metabolism Catabolism Anabolism
sometimes called biosynthetic pathways- Ex: synthesis of a protein from
amino acids.
Energy required/absorbed.
Organisms are energy transformers!
Metabolism and Energy
Metabolism Catabolism Anabolism
Bioenergetics the study of how energy flows through
living systems.
Organisms are energy transformers!
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
Organisms are energy transformers!
Metabolism and Energy
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
Organisms are energy transformers!
Metabolism and Energy
Energy Kinetic
Heat/Thermal comes from the movement of
atoms or molecules associated with kinetic energy
Organisms are energy transformers!
Metabolism and Energy
Energy Kinetic
Heat/Thermal
Light EnergyType of energy that can be harnessed to perform work
Ex. Powering Photosynthesis
Organisms are energy transformers!
Metabolism and Energy
Kinetic Heat/Thermal Light Energy
Potential Non-kinetic energy because of location or
structure, height, chemical bonds, etc.
Organisms are energy transformers!
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.
Organisms are energy transformers!
Metabolism and Energy
Organisms are energy transformers!
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 – TΔS
ΔG = 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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