Metabolism Metabolism the sum total of all the chemical reaction that take place to build up and break down the materials needed in an organism Catabolism the breaking down of complex molecules ID: 779949
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Slide1
Free Energy
All living systems require constant input of free energy
Slide2Metabolism
Metabolism
: the sum total of all the chemical reaction that take place to build up and break down the materials needed in an organism
Catabolism: the breaking down of complex moleculesExergonic: aka Spontaneous – happens on its own w/o energyReleases energy to surroundings/products are more stable than reactants∆G = -Increases disorder (more entropy)Anabolism: building complex complex molecules Endergonic: aka Nonspontaneous – requires energy to take placeStores or absorbs energy from surroundings/products are less stable than reactants ∆G = +Decreases Disorder (less entropy) Metabolic pathways: begin with specific molecule, altered in a series of defined steps, resulting in certain products
Enzyme 1
Enzyme 2
Enzyme 3
D
C
B
A
Reaction 1
Reaction 3
Reaction 2
Starting
molecule
Product
Slide3Reactants
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 ofenergyrequired(∆
G
> 0)
(b) Endergonic reaction: energy required
Progress of the reaction
Slide4Fig. 8-6a
Energy
(a) Exergonic reaction: energy released
Progress of the reaction
Free energy
Products
Amount of
energy
released
(∆
G
< 0)
Reactants
Slide5Fig. 8-6b
Energy
(b) Endergonic reaction: energy required
Progress of the reaction
Free energy
Products
Amount of
energy
required
(∆
G
> 0)
Reactants
Slide6Forms of Energy
Kinetic Energy
: motions – can do work by transferring motion to other matter
(ex: pool stick – ball to ball)Thermal energy: type of kinetic energy; aka heat; random movement of atoms or moleculesAnytime bonds are broken there is a transfer of energy from the molecule to thermal energy (called heat – this is why we say heat is released to the environment through the food chain – when glucose is broken down in the presences of oxygen bonds are broken some of the energy stored in the bonds of the glucose molecule becomes thermal energy this thermal energy is either lost to the environment OR if the organisms is an endotherm (relies on internal temperature control vs external (ectotherm)) the heat is used to maintain the organisms temperature (called thermoregulation)Potential Energy: energy matter posses because its location or structureChemical energy: potential energy available for release in a chemical reaction
Slide7Climbing 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 tokinetic energy.
A diver has more potentialenergy on the platformthan in the water.
Slide8Application
Describe the forms of energy found in an apple as it grows on a tree, then falls and is digested by someone who eats it.
Slide9Application Answer
The apple has
potential
energy in its position hanging on the tree, and the sugar and other nutrients it contains have chemical energy. The apple has kinetic energy as it falls from the tree to the ground. When the apple is digested and its molecules broken down, some of the chemical energy is used to do work, and the rest is lost as thermal energyWho knew…so many types of energy in one little apple!!!
Slide10Thermodynamics
Thermodynamics
: study of how energy is transferred (passed along) or transformed (changed into a different kind of energy)
System: matter under studyUniverse: everything outside the systemIsolated system: system unable to exchange either energy or matter with its surroundings; ex: thermos bottleOpen system: energy and matter can be exchanged between the system and its surrounds
Slide11Laws of Thermodynamics
First law
: Energy can be transferred and transformed, but it cannot be created or destroyed; principle of conservation of energy
Electric Company does not make energy; they convert it to a usable formPlants are not actually energy producers, more accurate to call them energy transformers.Second Law: Every energy transfer or transformation increases the entropy of the universe; for a process to be spontaneous, it must increase the entropy of the universe
Slide12What is Entropy?
Measure of disorder, or randomness
The more randomly arrange matter is, the greater its entropy
Although order can increase locally, the trend towards randomization of the universe is unstoppableAs chemical energy in food (C6H12O6) is converted into kinetic energy (movement) the release of CO2 + H2O + heat is causing the universe to become more disordered; localized order is increased at the expense of the universe becoming more disorderedFor a process to occur on its own it must increase the entropy of the universe; no energy is neededIf a reaction results in a product that is more ordered than the reactants it is going to require energy and will not take place on its own…endergonic or nonspontaneous
Slide13Free-Energy Change, ∆G
The following is an equation that can be used to determine the free energy available in a chemical reaction:
∆G = ∆H – T∆S
∆G = change in free energy; energy available to do work∆H = change in system’s enthalpy (in biological systems = total energy)T = absolute temperature in Kelvin (K)∆S = change in entropy; order of the systemIf ∆G = -- then the reaction will be spontaneous and occur without energy; if ∆G = + then the reaction will be nonspontaneous and will require energy
Slide14(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
Slide15Less free energy (lower
G
)
More stable Less work capacity
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∆G can be negative only when the process involves a loss of free energy during the change from initial state to final stateFree energy is the measure of a system’s instability – its tendency to change to a more stable state
Unless something prevents matter, it wants to move to a more stable stateFree energy (ability to do work) increases when a reaction is somehow pushed away from equilibrium A process is spontaneous and can perform work only when it is moving towards equilibrium
Slide16Fig. 8-5b
Spontaneous
change
Spontaneous
change
Spontaneous
change
(b) Diffusion
(c) Chemical reaction
(a) Gravitational motion
Slide17Digestion Time/Application
Assume temperature and enthalpy do not change…based on the equation for free energy change, how would entropy need to change in order for ∆G to be negative? Would entropy increase or decrease? If entropy increases, does that mean the reaction causes an increase in disorder or decrease in disorder?
Assume temperature and entropy do not change…based on the equation for free energy change, how would enthalpy need to change to cause ∆G to be negative? Would the reactants or products become more or less stable?
Slide18Digestion Debrieft
Increase in entropy (∆S) would lead to a negative ∆G
reaction would INCREASE in disorder
Decrease in enthalpy (∆H) would lead to a negative ∆G the products would be more stable than the reactants; the reaction is exergonic (releasing energy)
Slide19Three main kinds of work
Chemical work: pushing of endergonic reactions, which would not occur spontaneously, such as the synthesis of polymers from monomers
Transport work: pumping of substances across membranes against the direction of spontaneous movement
Mechanical work: movement (contraction of muscles, beating of cilia, movement of chromosomes during cell division)
Slide20Energy Coupling
Energy coupling: the use of an exergonic process to dive an endergonic reaction
ATP is responsible for most energy coupling in cells
Structure of ATP (adenosine triphosphate):Essential the RNA adenine nucleotide with two additional phosphate groups
3 Phosphate groups
Ribose
Adenine
Slide21Is ∆G negative or positive when ATP becomes ADP?
Inorganic phosphate
Energy
Adenosine triphosphate (ATP)
Adenosine diphosphate (ADP)
P
P
P
P
P
P
+
+
H
2
O
i
Which molecule is more stable?
Is there more of less disorder in ATP or ADP?
Is this reaction endergonic or exergonic?
Is this reaction spontaneous or non spontaneous?
Slide22(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
1
How ATP drives chemical work
ATP drives endergonic reactions by phosphorylation (transferring a phosphate group to some other molecule)
The recipient molecule is now phosphorylated
energy rich and unstable
The combined
rxns
are exergonic
Slide23(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
ATP
How ATP drives transport and mechanical work
The phosphate group from the ATP binds the the protein and causes the shape of the protein to change
Slide24The Regeneration of ATP
ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP)
ADP + P --> ATP
The energy to phosphorylate ADP comes from catabolic reactions in the cell.The chemical potential energy temporarily stored in ATP drives most cellular work.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Slide25The ATP cycle
P
i
ADP
+
Energy from
catabolism (
exergonic,
energy-releasing
processes)
Energy for cellular
work (
endergonic,
energy-consuming
processes)
+
H
2
O
ATP
Slide26How much total energy does an organisms need to stay alive?
Metabolic rate: amount of energy an animal uses in a unit of time
Can be determined in several ways:
Because nearly all of the chemical energy used in cellular respiration eventually appears as heat, metabolic rate can be measured by monitoring an animal’s rate of heat lossAmount of oxygen consumed or carbon dioxide produced Record the rate of food consumption, the energy content of the food and chemical energy lost in waste productsAmount of energy is going to differ depending on size, shape, and type of thermoregulation (how an organisms stay warm), age, activity, nutrition, temperatureEndotherm: internalEctotherm: external
Slide27Size and Metabolic Rate
In general smaller organisms have a higher metabolic rate than larger animals; a mouse needs more energy per unit mass compared to an elephant. This does not mean the elephant eats less than the mouse…it means the elephant needs less energy for every square inch of body mass compared to the mouse
Slide28Activity and Metabolic Rate
Increased activity = increased need for energy
Decreased activity = decreased need for energy
What happens when you have an excess supply of energy?Storage – what does this mean???What happens when you have a deficient of energy?Organism diesWhat impact does this have on the population? Ecosystem?Leads to disruptions in ecosystemsTo conserve on energy during times of stress some organisms go into a Torpor or Hibernation state (long term torpor)