Download presentation
Presentation is loading. Please wait.
1
Week 4 Energy and Enzymes
Forms of Energy Laws of Thermodynamics Energy and chemical reactions ATP – an energy carrier ATP Hydrolysis ATP and Phosphorylation ATP Cycle Enzymes Activation Energy and Rate of reactions Enzymes Mechanism Regulation of enzymes Metabolic Pathways Feedback Inhibition
2
Forms of Energy Kinetic Energy Potential Energy Movement
Thermal energy Light energy Potential Energy Positional energy Chemical energy
3
First Law of Thermodynamics
Law of Conservation of Energy Energy can be neither created nor destroyed, but can be transformed from one form into another. Implication – must account for source and fate of all energy in biological systems
4
Second Law of Thermodynamics
Law of Entropy Entropy (disorder) is tends to increase in closed systems “For a process to occur spontaneously, it most increase the entropy of the universe.”
5
Kinetic energy of movement
Figure 5.10 Fuel Energy conversion Waste products Heat energy Carbon dioxide Gasoline Combustion Kinetic energy of movement Oxygen Water Energy conversion in a car Heat energy Figure 5.10 Energy transformations in a car and a cell Cellular respiration Glucose Carbon dioxide ATP ATP Oxygen Energy for cellular work Water Energy conversion in a cell 5
6
Chemical Reactions and Energy
Hydrolysis Reaction Maltose + H2O Glucose 23 kcal/mol Dehydration Reaction 2 Glucoses Maltose + H2O 23 kcal/mol
7
Endergonic and Exergonic Reactions
Spontaneous Reactions Endergonic Reactions Non-spontaneous Reactions
8
Endergonic and Exergonic Reactions
Endergonic Reaction - nonspontaneous 3.4 kcal/mol Exergonic Reaction - spontaneous 7.2 kcal/mol
9
Overall still exergonic
Coupled Reactions 7.2 kcal/mol 3.8 kcal/mol 3.4 kcal/mol Overall still exergonic spontaneous
10
ATP Hydrolysis
11
Graphic Analysis of coupled reactions
Endergonic Reaction Exergonic Reaction Coupled Reaction Glutamate, Ammonia ATP Glutamine, ADP + P ATP Potential Energy of Molecules Potential Energy of Molecules Potential Energy of Molecules Glutamine Glutamate + Ammonia ADP + P Reactants Products Reactants Products Reactants Products How the cell provides energy for non spontaneous reactions.
12
ATP’s Energy Transferred by Phosphorylation
13
Energy from exergonic reactions Energy for endergonic reactions
ATP Phosphorylation Hydrolysis Energy from exergonic reactions Energy for endergonic reactions Figure 5.12C The ATP cycle ADP P 13
14
Speed of Exergonic Reactions
Paper + Oxygen Potential Energy of Molecules C20 Reactants Products Why are some spontaneous reactions very slow?
15
Speed of Spontaneous Reactions
Activation energy barrier Enzyme Activation energy barrier reduced by enzyme Reactant Reactant Energy Energy Figure 5.13A The effect of an enzyme in lowering EA Products Products Fast Spontaneous Reactions Slow spontaneous Reactions 15
16
C20 Exergonic Reaction Potential Energy of Molecules
Activation Energy Paper + Oxygen Potential Energy of Molecules C20 Reactants Products
17
How Enzymes speed up slow reactions
Activation energy barrier Enzyme Activation energy barrier reduced by enzyme Reactant Reactant Energy Energy Figure 5.13A The effect of an enzyme in lowering EA Products Products Without enzyme With enzyme Enzymes reduce the activation energy of exergonic reactions. 17
18
Enzyme available with empty active site
Figure 5.14_s4 1 Enzyme available with empty active site Active site Substrate (sucrose) 2 Substrate binds to enzyme with induced fit Enzyme (sucrase) Glucose Fructose H2O Figure 5.14_s4 The catalytic cycle of an enzyme (step 4) 4 Products are released 3 Substrate is converted to products 18
19
Normal binding of substrate
Figure 5.15A Substrate Active site Enzyme Allosteric site Normal binding of substrate Competitive inhibitor Noncompetitive inhibitor Figure 5.15A How inhibitors interfere with substrate binding Enzyme inhibition 19
20
Ibuprofen (like aspirin) is a competitive inhibitor
Figure 5.16 Ibuprofen (like aspirin) is a competitive inhibitor of an enzyme COX-2 which triggers the inflammatory response in tissues. Figure 5.16 Ibuprofen, an enzyme inhibitor 20
21
Metabolic Pathways Isoleucine pathway
22
Glycolysis
24
Feedback inhibition Enzyme 1 Enzyme 2 Enzyme 3 A B C D Reaction 1
Figure 5.15B Feedback inhibition Enzyme 1 Enzyme 2 Enzyme 3 A B C D Reaction 1 Reaction 2 Reaction 3 Starting molecule Product Figure 5.15B Feedback inhibition of a biosynthetic pathway 24
25
Feedback Inhibition Final product of the pathway – isoleucine is a non-competitive inhibitor of the first enzyme of the pathway
Similar presentations
