Metabolism Chapter 06

Outline 6.1 (p ) Forms of Energy ▫Laws of Thermodynamics 6.2 (p ) Metabolic Reactions ▫ATP 6.3 ( ) Metabolic Pathways ▫Energy of Activation ▫Enzymes ▫Photosynthesis ▫Cellular Respiration 2

Forms of Energy Kinetic:Mechanical; Energy of ________ Potential: Chemical; ________ energy 3

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 _________ 4

6.2 Metabolic Reactions and Energy 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 5

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 6

Work-Related Functions of ATP Primarily to perform cellular work ▫Chemical Work - Energy needed to __________________ ▫Transport Work - Energy needed to __________________ ▫Mechanical Work - Energy needed to __________________ 7

6.3 Metabolic Pathways Reactions usually occur in a sequence ▫_▫________of an earlier reaction become _______ of a later reaction ▫S▫Such linked reactions form a _______________ BBegins with a particular reactant, PProceeds through several ____________, and TTerminates with a particular end product 8 A  B  C  D  E  F  G “A” is Initial Reactant “G” is End Product Intermediates

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 9 E 1 E 2 E 3 E 4 E 5 E 6 A  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 _____________ 10

Energy of Activation 11

Enzyme-Substrate Complex The _________complexes with the substrates Causes active site to change ______ Shape change forces substrates together, initiating ______ Induced fit model 12

Induced Fit Model 13

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 14

Degradation vs. Synthesis 15

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 ___ 16

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 _____________ 17

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 18

Factors Affecting Enzyme Activity: Feedback Inhibition 19

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 20

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 21

22 Photosynthesis and Cellular Respiration Carbon dioxide +water +solar energy Glucose +oxygen  6CO 2 + 6H 2 O energy  C 6 H 12 O 6 + 6O 2 Carbon dioxide +water +chemical energy Glucose +oxygen  6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Cellular Respiration: 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 23

A Metaphor for the Electron Transport Chain 24

Chemiosmosis 25