metabolism energy coupling ss
TRANSCRIPT
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ENERGY AND THE CELL
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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.
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
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
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:
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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.
• Kinetic energy is the energy of motion• Potential energy is stored energy
- can be converted to kinetic energy & vice versa
Figure 5.1A–C
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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.
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.
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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.
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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.
Two laws govern energy transformations
• Thermodynamics• Is the study of energy transformations
1st Law of Thermodynamics, and –2nd Law of Thermodynamics
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 -
What are all the different forms of energy you see in this room?
Which ones are stored energy or kinetic energy?
What are all the different forms of energy you see in this room?
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
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
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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
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.
Discussion &/or Homework Assignment:
What is a “perpetual motion machine?”
The second law says that such a thing cannot exist . . .
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.
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).
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.
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Reactants
Energy Products
Amount ofenergy released
Pote
ntia
l ene
rgy
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.
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Reactants
Energy
Products
Amount ofenergy required
Pote
ntia
l ene
rgy
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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.
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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.
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
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
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.
• 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
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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.
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Triphosphate
Adenosine P
ATP
H2O Diphosphate
ADP Phosphate
Energy
P P
P P PAdenosine
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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
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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:
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.
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ATP synthesisis endergonic
ATP hydrolysisis exergonic
Energy fromcellular respiration(exergonic)
Energy forcellular work(endergonic)
ATP
ADP + P
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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.
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
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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
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: