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BIG IDEA II Biological systems utilize free energy and molecular building blocks BIG IDEA II Biological systems utilize free energy and molecular building blocks

BIG IDEA II Biological systems utilize free energy and molecular building blocks - PowerPoint Presentation

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BIG IDEA II Biological systems utilize free energy and molecular building blocks - PPT Presentation

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

free energy change pearson energy free pearson change reaction metabolic education 2008 copyright publishing benjamin cummings rate atp organisms

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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