MetabolismChapter 06

Outline• 6.1 (p.102-103) Forms of Energy

▫Laws of Thermodynamics

• 6.2 (p.104-105) Metabolic Reactions▫ATP

• 6.3 (106-111) Metabolic Pathways▫Energy of Activation

▫Enzymes

▫Photosynthesis

▫Cellular Respiration

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Forms of Energy• Kinetic: Mechanical; Energy of ________

• Potential: Chemical; ________ energy

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Laws of Thermodynamics• First law:

▫Law of ___________________

▫Energy cannot be created or destroyed, but can be _________ from one form to another

• Second law:▫Law of __________

▫When energy is changed from one form to another, there is a _____ of usable energy

▫Waste energy goes to increase _________

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6.2 Metabolic Reactions andEnergy Transformations• Metabolism: ________________________

▫________ participate in reaction

▫________ form as result of reaction

• __________is the amount of energy available to perform work

▫Exergonic Reactions - Products have ______ free energy than reactants

▫Endergonic Reactions - Products have _____ free energy than reactants

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ATP and Coupled Reactions•Adenosine triphosphate (___)

▫High energy compound used to drive metabolic reactions

▫Constantly being generated from adenosine diphosphate (___)

•ATP is composed of:▫_______ and ______ (together = adenosine),

and▫_______ phosphate groups

•Coupled reactions▫Energy released by an ________ reaction

captured in ATP▫That ATP used to drive an _________ reaction

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Work-Related Functionsof ATP•Primarily to perform cellular work

▫Chemical Work - Energy needed to __________________

▫Transport Work - Energy needed to __________________

▫Mechanical Work - Energy needed to __________________

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6.3 Metabolic Pathways

•Reactions usually occur in a sequence

▫________of an earlier reaction become _______ of a later reaction

▫Such linked reactions form a _______________

Begins with a particular reactant,

Proceeds through several ____________, and

Terminates with a particular end product

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AB C D E FG“A” is Initial

Reactant“G” is End

ProductIntermediates

Enzymes▫__________ molecules that function as catalysts

▫The reactants of an enzymatically accelerated reaction are called ___________

▫Each enzyme accelerates a specific reaction

▫Each reaction in a metabolic pathway requires a unique and specific ________

▫End product will not appear unless _____ enzymes present and functional

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E1 E2 E3 E4 E5 E6A B C D E F G

Enzymes:Energy of Activation• Reactants often “reluctant” to participate in

reaction

▫Energy must be __________ to at least one reactant to initiate the reaction

▫___________________

• Enzyme Operation:

▫Enzymes operate by _______________________

▫Accomplished by bringing the substrates into contact with _____________

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Energy of Activation

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Enzyme-Substrate Complex

•The _________complexes with the substrates

•Causes active site to change ______

•Shape change forces substrates together, initiating ______

•Induced fit model

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Induced Fit Model

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Degradation vs. Synthesis• Degradation:

▫Enzyme complexes with a ______ substrate molecule

▫Substrate is broken apart into ___ product molecules

• Synthesis:

▫Enzyme complexes with ___ substrate molecules

▫Substrates are __________and released as single product molecule

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Degradation vs. Synthesis

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Factors Affecting Enzyme Activity (1)• Substrate concentration

▫Enzyme activity __________ with substrate concentration ____________between substrate molecules and the

enzyme• Temperature

▫Enzyme activity ________ with temperature▫Warmer temperatures cause _______________

between enzyme and substrate▫However, ____ temperatures destroy enzyme

• pH▫Most enzymes are optimized for a particular

___

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Factors Affecting Enzyme Activity (2)•______ can affect presence/absence of enzyme

•______ can affect concentration of enzyme

•______ can activate or deactivate enzyme

▫Enzyme Cofactors

Molecules required to _______________

________ are organic cofactors, like some vitamins

Phosphorylation – some require _____________

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Factors Affecting Enzyme Activity (3)• __________ enzyme inhibition

▫When a substance known as an _________ binds to an enzyme and decreases its activity

________ inhibition – substrate and the inhibitor are both able to bind to active site

________ inhibition – the inhibitor binds not at the active site, but at the _________ site

▫__________ inhibition – The end product of a pathway inhibits the pathway’s first enzyme

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Factors Affecting Enzyme Activity:Feedback Inhibition

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Irreversible Inhibition•Materials that irreversibly inhibit an

enzyme are known as _________

•_______ inhibit enzymes resulting in all ATP production

•_______ inhibits an enzyme unique to certain bacteria

•_______ irreversibly bind with many enzymes

•_______irreversibly inhibits enzymes required by nervous system

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Oxidation-Reduction•Oxidation-reduction (redox) reactions:

▫________ pass from one molecule to another

The molecule that loses an electron is ________

The molecule that gains an electron is ________

▫Both take place at same time

▫One molecule ______ the electron given up by the other

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22Photosynthesis andPhotosynthesis andCellular RespirationCellular Respiration

Carbon dioxideCarbon dioxide+water+water+solar energy+solar energy

GlucoseGlucose+oxygen+oxygen

6CO6CO22 + 6H + 6H22OOenergyenergy

CC66HH1212OO66 + 6O + 6O22

Carbon dioxideCarbon dioxide+water+water+chemical energy+chemical energy

GlucoseGlucose+oxygen+oxygen

6CO6CO22 + 6H + 6H22OOCC66HH1212OO66 + 6O + 6O22

Cellular Respiration:Cellular Respiration:

Photosynthesis:Photosynthesis:

Electron Transport Chain• Membrane-bound carrier proteins found in ________

• Physically arranged in an ordered series

▫ Starts with high-energy electrons and low-energy ____

▫ Pass ________ from one carrier to another Electron energy used to pump ________(H+) to one side of

membrane

Establishes ___________across membrane

Electrical gradient used to make ___ from ___ – Chemiosmosis

▫ Ends with low-energy _______ and high-energy ATP

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A Metaphor for theElectron Transport Chain

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Chemiosmosis

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