Transcript Metabolism and Energy

Metabolism
and
Energy
Chapters 8
Metabolism and Energy
 Metabolism
 Catabolism
 Anabolism
 Bioenergetics
 Energy
 Kinetic
 Heat/Thermal
 Light Energy
 Potential
 Chemical
Organisms are energy
transformers!
Metabolism and Energy
 Metabolism
Organisms are energy
transformers!
 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 and Energy
 Metabolism
Organisms are energy
transformers!
 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).
Metabolism and Energy
 Metabolism
Organisms are energy
transformers!
 Catabolism
 Anabolism
 sometimes called biosynthetic
pathways-
 Ex: synthesis of a protein from
amino acids.
 Energy required/absorbed.
Metabolism and Energy
 Metabolism
 Catabolism
Organisms are energy
transformers!
 Anabolism
 Bioenergetics
 the study of how energy flows through
living systems.
Metabolism and Energy
 Metabolism
 Catabolism
 Anabolism
Organisms are energy
transformers!
 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
Metabolism and Energy
 Energy
Organisms are energy
transformers!
 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
Metabolism and Energy
Organisms are energy
transformers!
 Energy
 Kinetic
 Heat/Thermal
 comes from the movement of
atoms or molecules associated
with kinetic energy
Metabolism and Energy
Organisms are energy
transformers!
 Energy
 Kinetic
 Heat/Thermal
 Light Energy
Type of energy that can be harnessed
to perform work
Ex. Powering Photosynthesis
Metabolism and Energy
 Kinetic
Organisms are energy
transformers!
 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
Organisms are energy
transformers!
 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.
Metabolism and Energy
Organisms are energy
transformers!
All original energy comes
from light.
(photosynthesis- primary
producer- consumerwho 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 Energy
ΔG = 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 Energy
ΔG = 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
Non-Spontaneous
-ΔG
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
+
Substrate(s)
EnzymeSubstrate
Complex
Enzyme
+
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