metabolism energy coupling ss

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© 2015 Pearson Education, Inc. ENERGY AND THE CELL

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Page 1: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

ENERGY AND THE CELL

Page 2: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Cells transform energy as they perform work

• Cells are miniature chemical factories, housing thousands of chemical reactions.

• Some of these chemical reactions release energy, and others require energy.

• Energy changes forms • By definition, “Living Systems” can take in energy

and use it.

Page 3: Metabolism energy coupling ss

The light comes from a set of chemical reactions that occur in light producing organs in its abdomen

Cool “Fires” Attract Mates and Meals

• Fireflies (family Lampyridae) use light to send signals to potential mates instead of using chemical signals like most other insects

Page 4: Metabolism energy coupling ss

Females of some species produce a light pattern that attracts males of other species, which are then eaten by the female – Yummy!

Examples of energy conversions:

- Chemical bonds to light

- Chemical bonds to new chemical bonds and movement

Page 5: Metabolism energy coupling ss

ENERGY AND THE CELL

Energy is the capacity to perform workWork = defined as the capacity to cause change

• All organisms require energy to change • “Maintain homeostasis” and stay “alive”

• Change = “work”

There two basic types of energy forms:

Page 6: Metabolism energy coupling ss

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Gravity can move this biker down the mountain,

However –

How’d he get up there?

You know there is“stored energy” in this system, it’s just that –

You don’t know how much.

Page 7: Metabolism energy coupling ss

• Kinetic energy is the energy of motion• Potential energy is stored energy

- can be converted to kinetic energy & vice versa

Figure 5.1A–C

Page 8: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Cells transform energy as they perform work

Energy is the capacity to cause change or to perform work.There are two basic forms of energy.

1. Kinetic energy is the energy of motion.2. Potential energy is energy that matter

possesses as a result of its location or structure.

Page 9: Metabolism energy coupling ss

Cells transform energy as they perform work

• hermal energy is a type of kinetic energy associated with the random movement of atoms or molecules.

• Thermal energy in transfer from one object to another is called heat.

• Light is also a type of kinetic energy; it can be harnessed to power photosynthesis.

Page 10: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Cells transform energy as they perform work

Chemical energy is the• potential energy available for release in a chemical

reaction and

• the most important type of energy for living organisms to power the work of the cell.

Page 11: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Cells transform energy as they perform work

Thermodynamics is the study of energy transformations that occur in a collection of matter.

• The word system is used for the matter under study.

• The word surroundings is used for everything outside the system; the rest of the universe.

Page 12: Metabolism energy coupling ss

Two laws govern energy transformations

• Thermodynamics• Is the study of energy transformations

1st Law of Thermodynamics, and –2nd Law of Thermodynamics

Page 13: Metabolism energy coupling ss

The First Law of Thermodynamics

Energy cannot be created or destroyedThe total amount of energy in the universe is constant,

However –

Energy can be changed from one form to another

So, it might look like it’s being made or destroyed, but it’s just changing forms -

Page 14: Metabolism energy coupling ss

What are all the different forms of energy you see in this room?

Which ones are stored energy or kinetic energy?

Page 16: Metabolism energy coupling ss

Second Law =Energy transformations do not convert 100% of one type of energy into only one other type -

Most of the energy is converted to other types we cannot measure – that is, entropy

Page 17: Metabolism energy coupling ss

The Second Law of ThermodynamicsStates that energy transformations increase disorder or “entropy” Some energy lost as heat that organism uses anywayLiving systems have adapted to transfer energy efficiently

Figure 5.2B

Heat

Chemical reactions

ATP ATP

Glucose

+

Oxygen

water

Carbon dioxide

+

Energy for cellular work

Page 18: Metabolism energy coupling ss

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Fuel Energy conversion Waste products

Gasoline

Oxygen

Heatenergy

CombustionKinetic energyof movement

Carbon dioxide

Water

Energy conversion in a car

+ +

Glucose

Oxygen

Carbon dioxide

Water

+ +

Heatenergy

Energy conversion in a cell

ATP

Energy for cellular work

ATP

Cellular respiration

Page 19: Metabolism energy coupling ss

Cells transform energy as they perform work

• Automobile engines and cells use the same basic process to make the chemical energy of their fuel available for work.

• In the car and cells, the waste products are carbon dioxide and water.

• Cells use oxygen in reactions that release energy from fuel molecules.

• In cellular respiration, the chemical energy stored in organic molecules is used to produce ATP, which the cell can use to perform work.

Page 20: Metabolism energy coupling ss

Discussion &/or Homework Assignment:

What is a “perpetual motion machine?”

The second law says that such a thing cannot exist . . .

Page 21: Metabolism energy coupling ss

Cells transform energy as they perform work

Two laws govern energy transformations in organisms.

• Per the first law of thermodynamics (also known as the law of energy conservation), energy in the universe is constant.

• Per the second law of thermodynamics, energy conversions increase the disorder of the universe.

Entropy is the measure of disorder or randomness.

Page 22: Metabolism energy coupling ss

Chemical reactions either release or store energy

Chemical reactions either

• release energy (exergonic reactions) or

• require an input of energy and store energy (endergonic reactions).

Page 23: Metabolism energy coupling ss

Chemical reactions either release or store energy

Exergonic reactions release energy.• These reactions release the energy in covalent

bonds of the reactants.• Burning wood releases the energy in glucose as

heat and light.• Cellular respiration

• involves many steps,• releases energy slowly, and• uses some of the released energy to produce ATP.

Page 24: Metabolism energy coupling ss

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Reactants

Energy Products

Amount ofenergy released

Pote

ntia

l ene

rgy

Page 25: Metabolism energy coupling ss

Chemical reactions either release or store energy

An endergonic reaction• requires an input of energy and• yields products rich in potential energy.

Endergonic reactions• start with reactant molecules that contain relatively

little potential energy but• end with products that contain more chemical

energy.

Page 26: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Reactants

Energy

Products

Amount ofenergy required

Pote

ntia

l ene

rgy

Page 27: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Chemical reactions either release or store energy

Photosynthesis is a type of endergonic process.In photosynthesis,

• energy-poor reactants (carbon dioxide and water) are used,

• energy is absorbed from sunlight, and• energy-rich sugar molecules are produced.

Page 28: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Chemical reactions either release or store energy

A living organism carries out thousands of endergonic and exergonic chemical reactions.• The total of an organism’s chemical reactions is

called metabolism.A metabolic pathway is a series of chemical reactions that either

• builds a complex molecule or • breaks down a complex molecule into simpler

compounds.

Page 29: Metabolism energy coupling ss

Chemical reactions either store or release energy• Endergonic reactions absorb energy and yield

products rich in potential energy• Anabolic reactions (anabolism)

Pot

entia

l ene

rgy

of m

olec

ules

Reactants

Energy required

Products

Amount of energy

required

Page 30: Metabolism energy coupling ss

Exergonic reactions = release energy and yield products that contain less potential energy than their reactants = Catabolic reactions, catabolism

Reactants

Energy released

Products

Amount of energy

released

Pot

entia

l ene

rgy

of m

olec

ules

Page 31: Metabolism energy coupling ss

Chemical reactions either release or store energy

Energy coupling uses the energy released from exergonic reactions to drive endergonic reactions, typically using the energy stored in ATP molecules.

Page 32: Metabolism energy coupling ss

• Metabolism = The sum of all the chemical reactions in an organism. {Cells carry out thousands of chemical reactions}

• Energy coupling = shuttle energy from exergonic reactions to fuel endergonic reactions

ATP couples chemical energy and drives cellular work = Energy Exchange Molecule• ATP powers nearly all forms of cellular work

Page 33: Metabolism energy coupling ss

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ATP drives cellular work by coupling exergonic and endergonic reactions

• ATP, adenosine triphosphate, powers nearly all forms of cellular work.

• ATP consists of• adenosine and• a triphosphate tail of three phosphate groups.

Page 34: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Triphosphate

Adenosine P

ATP

H2O Diphosphate

ADP Phosphate

Energy

P P

P P PAdenosine

Page 35: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

The energy in an ATP molecule is carried in the bonds between its phosphate groups

Phosphategroups

ATP

EnergyP P PP P P HydrolysisAdenine

Ribose

H2O

Adenosine diphosphateAdenosine Triphosphate

++

ADP

Page 36: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

ATP

ADP + P

Energy forendergonicreactions

Energy fromexergonicreactions

Pho

spho

ryla

tion

Hydr olysis

– Cellular work can be sustained, because ATP is a renewable resource that cells regenerate

– ATP Cycle:

Page 37: Metabolism energy coupling ss

ATP drives cellular work by coupling exergonic and endergonic reactions

• A cell uses and regenerates ATP continuously.• In the ATP cycle, energy released in an exergonic

reaction, such as the breakdown of glucose during cellular respiration, is used in an endergonic reaction to generate ATP from ADP.

Page 38: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

ATP synthesisis endergonic

ATP hydrolysisis exergonic

Energy fromcellular respiration(exergonic)

Energy forcellular work(endergonic)

ATP

ADP + P

Page 39: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

ATP drives cellular work by coupling exergonic and endergonic reactions

There are three main types of cellular work:1. chemical,2. mechanical, and3. transport.

• ATP drives all three of these types of work.

Page 40: Metabolism energy coupling ss

ATP drives cellular work by coupling exergonic and endergonic reactions

• Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule in a process called phosphorylation.

• Most cellular work depends on ATP energizing molecules by phosphorylating them.

• ATP drives endergonic reactions by phosphorylation• Transferring a phosphate group onto a molecule to

make it more reactive

Page 41: Metabolism energy coupling ss

© 2015 Pearson Education, Inc.

Chemical work

ATP P

Reactants Product formed

ADP +

P

P

ATP

PADP +

P

P

ATP P ADP +P P

Transport work

Transport protein Solute transported

Mechanical work

Motor protein Protein filament moved

Page 42: Metabolism energy coupling ss

Metabolism = all the chemical reactions in an organism

Cells need a mechanism for linking chemical reactions, by

1. Coupling energy between endergonic & exergonic reactions.

= ATP Cycle couples anabolism to catabolism

2. Reactions need to occur fast enough to pass their products onto the next reaction.

So – Run reactions in a series, one after another,in Metabolic pathways

- using protein catalysts called ENZYMES: