1. Metabolism

2. Energy All living things need energy
No Energy= Death!!!
Free energy is energy available for work
Chemical energy is energy stored in chemical bonds of molecules
What is the main source of energy for all life on earth?

3. Flow of energy through life
organic molecules  ATP & organic molecules
sun
organic molecules  ATP & organic molecules
organic molecules  ATP & organic molecules
sun
organic molecules  ATP & organic molecules
solar energy  ATP & organic molecules

4. Chemical Reactions
Reactants PRODUCTS CH4 + 2O2 CO2 + 2H2O Living things are energy converters Light energy  chemical energy electric energy

5. Laws of Thermodynamics
First law…Law of Conservation of Energy
*Energy cannot be created or destroyed only transferred or transformed
Why is this statement incorrect:
Plants create their own energy.
Second law…Entropy
Every chemical reaction increases disorder in the universe
With every chemical reaction that transfers/transforms energy, some of that energy is converted into thermal energy and lost as heat

6. Metabolism
What is metabolism?

7. Metabolism
Metabolism is all of the chemical reactions occurring in a biological system at a given time *Involves energy changes -Energy is either stored in chemical bonds or -Energy is released from chemical bonds 2 parts to metabolism -Anabolic pathways -Catabolic pathways

8. Anabolic Pathway
Anabolic pathways…consume (use) energy to build complex molecules from simpler ones
Sound familiar?
Other examples?
Keys to identify…Look for
-Building or synthesizing
-Require energy
Why?

9. Catabolic pathway
Catabolic pathways…release energy by breaking down complex molecules into simpler compounds Again…sound familiar? Keys to identify…Look for Breakdown or decomposition Release energy Why?

10. Catabolic and anabolic coupling
In organisms, catabolic reactions are used to drive anabolic reactions
energy + +
energy + +

11. Exergonic Exergonic Reactions
Chemical reactions that release free energy
Connected to…
Example?

12. Endergonic Endergonic Reactions
Chemical reactions that absorb free energy
Connected to…
Example?

13. Amount of energy required (G  0)
(b) Endergonic reaction: energy required,
nonspontaneous
Products
Amount of
energy
required
(G  0)
Energy
Free energy
Reactants
Figure 6.6b Free energy changes (ΔG) in exergonic and endergonic reactions (part 2: endergonic)
Progress of the reaction 13

14. Amount of energy released (G  0)
(a) Exergonic reaction: energy released, spontaneous
Reactants
Amount of
energy
released
(G  0)
Energy
Free energy
Products
Figure 6.6a Free energy changes (ΔG) in exergonic and endergonic reactions (part 1: exergonic)
Progress of the reaction 14

15. Metabolic pathways
Series of chemical reactions (anabolic and catabolic) in which the products of one reaction becomes the reactants of the next *Controlled by enzymes Hundreds of enzymes in each cell are involved in inter-connecting pathways Metabolite= a molecule in a metabolic pathway

16. Control of pathways
To control metabolic pathways the cell regulates the amounts of enzymes involved in each pathway 2 ways: Turn the genes on or off that build enzyme Turn enzymes on or off