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ENERGY. Energy capacity to perform work done when objects are moved against opposing forces & things move in directions in which they would not have moved.

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Presentation on theme: "ENERGY. Energy capacity to perform work done when objects are moved against opposing forces & things move in directions in which they would not have moved."— Presentation transcript:


2 Energy capacity to perform work done when objects are moved against opposing forces & things move in directions in which they would not have moved if left alone body needs energy cells are biggest users of energy in the body need energy to make complex molecules from monomer building blocks-anabolic reactions need energy to break down macromolecules- catabolic reactions to obtain energy to do all of the activities they need to do everyday

3 First Law of Thermodynamics energy cannot be destroyed nor created energy can be converted from one form to another plants convert energy in sunlight into chemical energy life forms use to perform activities of life cant use energy over & over each time there is energy transfer some energy becomes unusable

4 Forms of Energy Kinetic energy –energy of motion Potential energy –stored energy –energy an object has as result of its locomotion or structure

5 Forms of Energy

6 Energy Flow energy flows into our ecosystem as sunlight kinetic energy (from sun) is transformed into chemical energy-potential energy of food & fuels by photosynthesis

7 Energy Flow animals consume food products to provide ATP or energy for cells to perform work

8 Endergonic Reactions yield potential energy require input of energy products acquire more energy than reactants energy is stored in covalent bonds of products photosynthesis is an endergonic reaction

9 Exergonic Reactions release energy reactions begin with reactants whose covalent bonds contain more energy than in products & release energy to the environment occur in cells of body cellular respiration oxygen is used to convert chemical energy stored in fuel molecules (glucose) to chemical energy (ATP) cell uses to carry on its processes Glucose + O 2 CO 2 + H 2 O

10 ATP-Adenosine Triphosphate provides energy for cellular work consists of adenine –nitrogenous base ribose –five carbon sugar called adenosine 3 PO 4 groups attached-triphosphate part phosphate bonds are unstable can be easily broken by hydrolysis in exergonic reactions each PO 4 group released from ATP yields 7Kcal of energy one phosphate group removed ATP ADP + pi + 7Kcal of energy –adenosine diphosphate + inorganic phosphate + energy another phosphate removed AMP + pi + 7Kcal of energy –adenosine monophosphate

11 Cellular Metabolism every working cell in body performs exergonic & endergonic reactions sum-cellular metabolism energy released from exergonic reactions is used to drive endergonic reactions energy coupling ATP functions in energy coupling

12 Energy Coupling

13 Factors in Chemical Reactions many molecules in body store tremendous amount of potential energy do not spontaneously break down into smaller components to initiate reactions reactants need to overcome an energy barrier amount of energy that compound must absorb before chemical reaction can begin-activation energy requires a catalyst something to speed rate of reaction

14 Enzymes speed rate of reactions lower activation energy globular proteins names typically end in –ase each has a unique 3- D shape shape determines which reactions enzyme can catalyze

15 Enzymes specific reactant for specific enzyme- substrate fits into specific area- active site once product forms enzyme detaches from active site free to start another reaction

16 Enzyme Action

17 Saturation Limit reaction rate is proportional to concentration of substrate & concentration of enzyme enzyme must meet with specific amount of substrate before catalysis can begin higher substrate concentrations more frequently encountered by enzyme when substrate concentrations are high enough so every enzyme molecule is cycling through its reaction sequence at top speed further increase in substrate concentration will not effect rate of reaction unless more enzyme is added substrate concentration at which rate of a reaction is maximum is saturation limit

18 Regulation of Enzymatic Reactions many variables turn enzymes on & off to control reaction rates enzymes are proteins protein shapes can be changed by the environment Temperature Salt concentration pH

19 Regulators of Enzymatic Activity Cofactors –i–ions or molecules that bind to enzyme before substrate can bind allows enzymes to be active sometimes & inactive at other times several important inorganic cofactors-zinc, iron & copper organic cofactors are coenzymes most made from vitamins or are vitamins

20 Inhibition of Enzymatic Activity chemicals that interfere with enzyme function-inhibitors competitive inhibitors –fit into active sites so real substrate cannot noncompetitive inhibitors –bind at sites other than active site –changes enzymes shape –causes active site to no longer recognize substrate


22 Inhibition Reversible inhibitors –can serve a regulatory function –turn enzyme on when needed –turn it off when not Irreversible inhibitors –kill enzyme function –poisons –block metabolic processes that are essential to survival

23 Irreversible Inhibition Penicillin inhibits enzymes in bacteria needed to make cells walls since humans do not have this enzyme penicillin can be used to kill the bug without effecting human cells

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