1. Chapter 6 BIOL1000 Dr. Mohamad H. Termos
Metabolism: Energy and Enzymes
Chapter 6 BIOL1000 Dr. Mohamad H. Termos

2. Cells and the Flow of Energy
Biology, 9th ed,Sylvia Mader
Chapter 06
Cells and the Flow of Energy
Energy – The ability to do work or bring about a change
Kinetic energy
Energy of motion
Mechanical
Potential energy
Stored energy
Chemical energy
Metabolism

3. Biology, 9th ed,Sylvia Mader
Chapter 06
Energy
Energy is needed for: “doing work”
growth
development
metabolism
reproduction
Metabolism

4. Two Laws of Thermodynamics
Biology, 9th ed,Sylvia Mader
Chapter 06
Two Laws of Thermodynamics
First law: Law of conservation of energy
Energy cannot be created or destroyed
Energy can be changed from one form to another
Second law: Law of entropy
When energy is changed from one form to another, there is a loss of usable energy
Metabolism

5. Metabolic Reactions and Energy Transformations
Biology, 9th ed,Sylvia Mader
Chapter 06
Metabolic Reactions and Energy Transformations
Metabolism
Sum of cellular chemical reactions in cell
Reactants - participate in a reaction
Products - form as result of a reaction
Reactants  Products
Free energy - the amount of energy available to
perform work
Exergonic Reactions - release energy
Endergonic Reactions - require energy input
Metabolism

6. Biology, 9th ed,Sylvia Mader
Chapter 06
ATP: Energy for Cells
Adenosine triphosphate (ATP)
High energy compound used for metabolic reactions
Constantly being generated from adenosine diphosphate (ADP)
Composed of:
Adenine, ribose (together = adenosine), and three phosphate groups
Coupled reactions
Energy released by an exergonic reaction captured in ATP
ATP is used to drive an endergonic reaction
Metabolism

7. Metabolic Pathways and Enzymes
Biology, 9th ed,Sylvia Mader
Chapter 06
Metabolic Pathways and Enzymes
Metabolic pathway- series of linked reactions
Enzyme
Protein molecules that function as catalysts
The reactants are known as substrates when enzymes are used
Each enzyme accelerates a specific reaction
Each reaction requires a unique and specific enzyme
The end product will not be formed unless ALL enzymes in the pathway are present and functional
E1 E2 E3 E4 E5 E6
A  B  C  D  E  F  G
Metabolism

8. Biology, 9th ed,Sylvia Mader
Chapter 06
The enzyme binds to the substrate (reactant)
Changes shape and the reaction occurs
Product released after rxn
Enzyme can bind with another substrate now
The active site is a place where the substrates fit onto the enzyme in such a way that they are oriented to react
Metabolism

9. Enzyme-Substrate Complex
Biology, 9th ed,Sylvia Mader
Chapter 06
Enzyme-Substrate Complex
Degradation: Single substrate is broken apart into two product molecules
Synthesis: Two substrates are joined together and released as a single product molecule
Metabolism

10. Factors Affecting Enzymatic Speed
Biology, 9th ed,Sylvia Mader
Chapter 06
Factors Affecting Enzymatic Speed
Substrate concentration
Temperature pH
Most enzymes are optimized for a particular pH
Metabolism

11. Factors Affecting Enzymatic Speed
Biology, 9th ed,Sylvia Mader
Chapter 06
Factors Affecting Enzymatic Speed
Cells can regulate:
the presence/absence of an enzyme
the concentration of an enzyme
activate or deactivate some enzymes
Enzyme Cofactors
Molecules required to activate enzyme
Metabolism

12. Biology, 9th ed,Sylvia Mader
Chapter 06
Enzyme Inhibition
Reversible enzyme inhibition
A substance known as an inhibitor binds to an enzyme and decreases its activity
Metabolism

13. Enzyme Inhibitors Can Spell Death
Biology, 9th ed,Sylvia Mader
Chapter 06
Enzyme Inhibitors Can Spell Death
Materials that irreversibly inhibit an enzyme are known as poisons
Cyanide inhibits enzymes required for ATP production
Warfarin inhibits an enzyme responsible for the blood clotting process
Metabolism

14. Photosynthesis and Cellular Respiration
Biology, 9th ed,Sylvia Mader
Chapter 06
Photosynthesis and Cellular Respiration
Metabolism

15. Chapter 7 BIOL1000 Dr. Mohamad H. Termos
Photosynthesis
Chapter 7 BIOL1000 Dr. Mohamad H. Termos

16. Photosynthetic Organisms
Biology, 9th ed,Sylvia Mader
Chapter 07
Photosynthetic Organisms
All life on Earth depends on solar energy
Photosynthesis:
Solar energy  chemical energy
Energy is stored in a carbohydrate.
The oxygen that is released as O2 during photosynthesis came from the water molecules
Photosynthesis

17. Biology, 9th ed,Sylvia Mader
Chapter 07
Photosynthesis takes place in the green portions of plants (cells with chloroplasts).
The pigment molecules responsible for photosynthesis are located in the thylakoid membrane of the chloroplasts.
The process needs water, carbon dioxide and energy
Roots absorb water that moves up vascular tissue
Energy supplied by light
Chlorophyll and other pigments absorb solar energy
Photosynthesis

18. Biology, 9th ed,Sylvia Mader
Chapter 07
Mesophyll- contains many chloroplasts
Stoma- opens to allow carbon dioxide in.
2 sets of reactions:
Light Reaction:
Solar energy becomes chemical energy (ATP and NADPH). Light is required for the light dependent reactions because it energizes electrons in the reaction center
Calvin Cycle Reaction
Chemical energy (ATP and NADPH) becomes chemical energy (Carbohydrate)
Photosynthesis