to grow to reproduce and to maintain dynamic homeostasis Enduring Understanding 2A Growth reproduction and maintenance of the organization of living systems require free energy and matter Essential Knowledge 2A1 ID: 723483
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Slide1
BIG IDEA IIBiological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis.
Enduring Understanding 2.A
Growth, reproduction and maintenance of the organization
of living systems require free energy and matter.
Essential Knowledge 2.A.1
All living systems require a constant input of free energy.Slide2
Essential Knowledge 2.A.1: All living systems require a constant input of free energy.Learning Objectives:
(2.1)
The student is able to
explain
how biological systems use free energy
based on empirical data
that all organisms require constant energy input to maintain organization, to grow and to reproduce.
(2.2)
The student is able to
justify a scientific claim
that free energy is required for living systems to maintain organization, to grow or to reproduce, but that multiple strategies exist in different living systems.
(2.3)
The student is able to
predict
how changes in free energy availability affect organisms, populations and ecosystems.Slide3
Fig. 9-2
Light
energy
ECOSYSTEM
Photosynthesis
in chloroplasts
CO
2
+ H
2O
Cellular respirationin mitochondria
Organicmolecules
+ O2
ATP powers most cellular work
Heatenergy
ATPSlide4
Life Requires a Highly Ordered SystemThe living cell is a chemical factory in miniature, where thousands of reactions occur within a microscopic space.
Order is maintained by constant free energy input into the system.
Loss of order or free energy flow results in death.
Increased disorder and entropy are offset by biological processes that maintain or increase order.
The concepts of metabolism help us to understand how matter and energy flow during life’s processes and how that flow is regulated in living systems.Slide5
MetabolismMetabolism is the totality of an organism’s chemical reactions:An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics.
Metabolism is an emergent property of life that arises from interactions between molecules within the cell.
A
metabolic pathway
begins with a specific molecule and ends with a product, whereby each step is catalyzed by a specific enzyme.
Bioenergetics is the study of how organisms manage their energy resources.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide6
Enzyme 1
Enzyme 2
Enzyme 3
D
C
B
A
Reaction 1
Reaction 3
Reaction 2
Starting
molecule
Product
Overview:
A Metabolic PathwaySlide7
Catabolic pathways release energy by breaking down complex molecules into simpler compounds:Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism.Anabolic pathways consume energy
to build complex molecules from simpler ones:
The synthesis of protein from amino acids is an example of anabolism.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Catabolism and AnabolismSlide8
Forms of EnergyEnergy is the capacity to cause change.Energy exists in various forms, some of which can perform work:
Kinetic energy
is energy associated with motion.
Heat (thermal energy)
is kinetic energy associated with random movement of atoms or molecules.
Potential energy is energy that matter possesses because of its location or structure.
Chemical energy is potential energy available for release in a chemical reaction.Energy cannot be created or destroyed, but can be converted from one form to another.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide9
Climbing up converts the kinetic
energy of muscle movement
to potential energy.
A diver has less potential
energy in the water
than on the platform.
Diving converts
potential energy to
kinetic energy.
A diver has more potentialenergy on the platformthan in the water.Slide10
The Laws of Energy TransformationThermodynamics is the study of energy transformations.A closed system
, such as that approximated by liquid in a thermos, is isolated from its surroundings.
In an
open system
, energy and matter can be transferred between the system and its surroundings.
Organisms are open systems.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide11
The First Law of ThermodynamicsAccording to the
first law of thermodynamics
, the energy of the universe is constant:
–
Energy can be transferred and transformed, but it cannot be created or destroyed
The first law is also called the principle of conservation of energy.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide12
The Second Law of ThermodynamicsDuring every energy transfer or transformation, some energy is unusable, and is often lost as heat.According to the
second law of thermodynamics
:
–
Every energy transfer or transformation increases the entropy (disorder) of the universe.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide13
(a) First law of thermodynamics
(b) Second law of thermodynamics
Chemical
energy
Heat
CO
2
H
2
O
+Slide14
Biological Order and DisorderCells create ordered structures from less ordered materials.Organisms also replace ordered forms of matter and energy with less ordered forms.
Energy flows into an ecosystem in the form of light and exits in the form of heat.
The evolution of more complex organisms
does not
violate the second law of thermodynamics.
Entropy (disorder) may decrease in an organism, but the universe’s total entropy increases.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide15
Free-Energy Change, GThe free-energy change
of a reaction tells us whether or not the reaction occurs spontaneously.
Biologists often want to know which reactions occur spontaneously and which require input of energy.
To do so, they need to determine energy changes that occur in chemical reactions.
A living system’s
free energy is energy that can do work when temperature and pressure are uniform, as in a living cell.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide16
The change in free energy (∆G) during a process is related to the change in enthalpy, or change in total energy (∆H), change in entropy (∆S), and temperature in Kelvin (T):
∆
G
= ∆
H – T
∆SOnly processes with a negative ∆G are spontaneous.Spontaneous processes can be harnessed to perform work.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Free-Energy Change,
GSlide17
Free Energy, Stability, and EquilibriumFree energy is a measure of a system’s instability, its tendency to change to a more stable state.During a spontaneous change, free energy decreases and the stability of a system increases.
Equilibrium
is a state of maximum stability.
A process is spontaneous and can perform work only when it is moving toward equilibrium.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide18
(a) Gravitational motion
(b) Diffusion
(c) Chemical reaction
More free energy (higher
G
)
Less stable
Greater work capacity
In a spontaneous change
The free energy of the system
decreases (∆G < 0)
The system becomes more stable
The released free energy can be harnessed to do work
Less free energy (lower G) More stable Less work capacity Slide19
Free Energy and MetabolismThe concept of free energy can be applied to the chemistry of life’s processes:An exergonic reaction proceeds with a net release of free energy and is spontaneous (∆
G
is negative).
An
endergonic reaction
absorbs free energy from its surroundings and is nonspontaneous (∆G is positive).
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide20
Reactants
Energy
Free energy
Products
Amount of
energy
released
(∆
G
< 0)
Progress of the reaction
(a) Exergonic reaction: energy released
Products
Reactants
Energy
Free energy
Amount of
energy
required
(∆
G
> 0)
(b) Endergonic reaction: energy required
Progress of the reactionSlide21
(a) An isolated hydroelectric system
∆
G
< 0
∆
G
= 0
(b) An open hydroelectric
system
∆
G < 0
∆G < 0
∆G < 0
∆G < 0
(c) A multistep open hydroelectric systemSlide22
H
2
O
ATP & Energy Coupling
Energetically favorable exergonic reactions, such as ATP
ADP, that have negative change in free energy can be used to maintain or increase order in a system by being coupled with reactions that have a positive free energy exchange.Slide23
Inorganic phosphate
Energy
Adenosine triphosphate (ATP)
Adenosine diphosphate (ADP)
P
P
P
P
P
P
+
+
H
2
O
iSlide24
(b) Coupled with ATP hydrolysis, an exergonic reaction
Ammonia displaces
the phosphate group,
forming glutamine.
(a) Endergonic reaction
(c) Overall free-energy change
P
P
Glu
NH
3
NH
2
Glu
i
Glu
ADP
+
P
ATP
+
+
Glu
ATP phosphorylates
glutamic acid,
making the amino
acid less stable.
Glu
NH
3
NH
2
Glu
+
Glutamic
acid
Glutamine
Ammonia
∆
G
= +3.4 kcal/mol
+
2
1Slide25
(b) Mechanical work: ATP binds noncovalently
to motor proteins, then is hydrolyzed
Membrane protein
P
i
ADP
+
P
Solute
Solute transported
P
i
Vesicle
Cytoskeletal track
Motor protein
Protein moved
(a) Transport work: ATP phosphorylates
transport proteins
ATP
ATPSlide26
Energy Related Pathways in Biological SystemsEnergy-related pathways in biological systems are sequential and may be entered at multiple points in the pathway:GlycolysisKrebs cycle
Calvin cycle
Fermentation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide27
Use of Free EnergyOrganisms use free energy to maintain organization, grow and reproduce. Illustrative Examples include:Strategies to regulate body temperature
Strategies for reproduction & rearing of offspring
Metabolic rate and size
Excess acquired free energy
Insufficient acquired free energy
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide28
Animals use the chemical energy in food to sustain form and function.All organisms require chemical energy for growth, repair, physiological processes, regulation, and reproduction.The flow of energy through an animal, its bioenergetics, ultimately limits the animal’s behavior, growth, and reproduction – which determines how much food it needs.Studying an animal’s bioenergetics tells us a great deal about the animal’s adaptations.
Bioenergetics of AnimalsSlide29
Bioenergetics of an AnimalSlide30
An animal’s metabolic rate is the amount of energy it uses in a unit of time.An animal’s metabolic rate is closely related to its bioenergetic strategy – which determines nutritional needs and is related to an animal’s size, activity, and environment:The
basal metabolic rate
(BMR) is the metabolic rate of a non-growing, unstressed endotherm at rest with an empty stomach.
The
standard metabolic rate
(SMR) is the metabolic rate of a fasting, non-stressed ectotherm at rest at a particular temperature.For both endotherms and ectotherms, size and activity has a large effect on metabolic rate.
Quantifying Energy UseSlide31
Organisms use various strategies to regulate body temperature and metabolism.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin CummingsSlide32
Elevated Floral Temperature in Some Plant SpeciesSlide33
Different organisms use various reproductive strategies in response to energy availability.Slide34
Seasonal Reproduction in PlantsSlide35
There is a relationship between metabolic rate per unit body mass and the size of multicellular organisms – generally, the smaller the organism, the higher the metabolic rate.
Larger animals have more body mass and therefore require more chemical energy.
Remarkably, the relationship between overall metabolic rate and body mass is constant across a wide range of sizes and forms.
Metabolic Rate and Size of OrganismsSlide36
Metabolic Rate and Size of OrganismsSlide37
Changes in free energy availability can result in changes in population size and disruption to an ecosystem.
Change in the producer level can affect the number and size of other trophic levels.
Change in energy resource levels such as sunlight can affect the number and size of the trophic levels.
Changes in Free Energy AvailabilitySlide38
Changes in Free Energy Availability