1. Metabolism and Energy
SBI4U1

2. All chemical reactions change matter and energy in cells
What is Metabolism?
All chemical reactions change matter and energy in cells
Via metabolic pathways
Metabolic Pathways: multiple chemical reaction catalysed by enzymes
Function to break down energy rich compounds like glucose for energy

3. Catabolism: breaking down to smaller compounds to release energy Anabolism: building larger molecules using energy

4. Energy
Some physics terms... Energy: capacity to do work Kinetic Energy: energy of motion Potential Energy: stored energy

5. The weight has potential energy as it is suspended in the air.
Once it is dropped the potential energy is transformed to kinetic energy.
Potential energy is converted to kinetic energy in living cells, this is how molecules are moved into and out of cells in active transport.

6. Bond Energy: the amount of energy required to break or form a chemical bond Energy released from rxns in living things can be thermal, the movement of molecules, contraction of a muscle, or the emission of light.

7. Laws of Thermodynamics
1st Law of Thermodynamics
Law of conservation of energy
Energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another.

8. 2nd Law of Thermodynamics
Transformation of potential energy into heat, or random motion.
During any process, the universe tends toward disorder.
Entropy (S): a measure of disorder

10. ordered (less stable)disordered (stable)
Energy transformation convert matter from:
ordered (less stable)disordered (stable)
This law only applies to closed systems.
Organisms are open systems and therefore highly ordered.
Energy is used to decrease randomness

11. Free Energy (G): energy from a chemical rxn available to do work
“G” is = to the energy contained in chemical bonds, called enthalpy.
Enthalpy (H): total energy of a thermodynamic system

12. G = H – TS
In a chemical rxn, the bonds of reactants are broken and the products form new bonds.
For chemical rxns under constant temperature, pressure and volume the change in free energy can be determined by:
ΔG = ΔH -TΔS

13. ΔG can predict the spontaneity of a rxn. If ΔG is +
Products > free energy than reactants
Bond energy, H, is higher
Entropy, S, is lower
Not spontaneous
Endergonic (absorb energy)
E.g. photosynthesis

14. ΔG>O; energy absorbed

15. If ΔG is – Products < free energy than reactants
Bond energy, H, is lower
Entropy, S, is higher
Spontaneous
Exergonic (release energy)
E.g. Cellular respiration

16. ΔG<O; energy released

17. Thermodynamics and Metabolism
Spontaneous rxn do not always occur
Must be initiated w/ energy (EA)
E.g. Combustion rxn
In cells, energy from catabolic rxns initiate anabolic rxns
The energy is ATP
Enzymes catalyse the rxn and lower EA

18. Hydrolysis of ATP 3rd phosphate group detached an exothermic rxn
ATP  adenosine triphosphate
ADP  adenosine diphosphate
3rd phosphate group detached an exothermic rxn
H2O is added
High energy bond breaks releasing energy
ATP ADP

19. Coupled Rxns
Spontaneous exergonic rxns release ATP and drive endergonic rxns
The rxns are coupled
Hydrolysis and synthesis of ATP is cyclical
Phosphorylation = addition of phosphate

20. Electron Carriers Redox rxns are coupled rxns
Recall: LEO goes GER
Electrons carry energy (reducing power)
Reduced = less energy
Oxidized = more energy
Electron carriers are compounds in cells that transfer electrons
From high energy compounds to low energy compounds

21. E.g. NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide)
These are oxidized forms
NADH and FADH2 are reduced forms
They play a role in cellular respiration

23. How the NAD+ Works

24. Things You Should Know... Metabolic Pathways Catabolism vs. anabolism
Bond energy
1st and 2nd Law of Thermodynamics
Entropy, Enthalpy, Free Energy
Endergonic vs. Exergonic
Hydrolysis of ATP
Coupled Rxns
Electron Carriers