1. Energy and Chemical Reactions
Metabolism The totality of an organism’s chemical reactions
Arises from interactions between molecules
The transformation of matter and energy
Subject to the laws of thermodynamics

2. Energy The ability to move and change matter Life requires energy.
Almost all energy for life is derived from the sun.
A productive way of viewing life is to see it as a set of coordinated chemical reactions.
This leads to an obvious question – What determines what chemical reactions are possible?

3. Thermodynamics The study of energy transformation
First law of thermodynamics: Energy can be transferred or transformed but
Neither created nor destroyed. For
example, the chemical (potential) energy
in food will be converted to the kinetic
energy of the cheetah’s movement in (b).
(a)
Chemical
energy
The study of energy transformation
The first law of thermodynamics
Energy can be transferred and transformed
Energy cannot be created or destroyed

4. Thermodynamics The second law of thermodynamics
Spontaneous changes that do not require outside energy increase the entropy of the universe
Entropy= disorder in the universe entropy is always increasing.
Second law of thermodynamics: Every energy transfer or transformation increases
the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s
surroundings in the form of heat and the small molecules that are the by-products
of metabolism.
(b)
Heat
co2
H2O +

5. The Direction of Spontaneous Reactions (and what it takes to go the other way)

6. Energy can be converted from one form to another
On the platform, a diver
has more potential energy.
Diving converts potential
energy to kinetic energy.
Climbing up converts kinetic
energy of muscle movement
to potential energy.
In the water, a diver has
less potential energy.

7. Flow of energy through life
Life is built on chemical reactions
transforming energy from one form to another
organic molecules  ATP & organic molecules
sun
organic molecules  ATP & organic molecules
solar energy  ATP & organic molecules

8. Energy (E) Transfer Overview
Energy transfer in the environment

9. Chemical Reactions
Reactants are the starting materials for chemical reactions
Products are the newly formed substances that result from the chemical reaction.
Energy is absorbed or released when chemical bonds are broken and new ones are formed.

10. Exergonic Reaction release energy
reactants
exergonic reaction
release energy
products contain less potential energy than their reactants
products

11. Endergonic Reaction absorb energy
products
endergonic reaction
reactants
absorb energy
yield products rich in potential energy

12. The “Nature of Life” – Coupling Favorable to Unfavorable Reactions
Energy and Enzymes
2/17/2019
The “Nature of Life” – Coupling Favorable to Unfavorable Reactions
Chemical Reactions
G. Podgorski, Biol. 1010

13. Energy content of common
chemicals (foods)
Energy used in activities

14. Activation Energy
Energy needed to start a chemical reaction

15. Enzymes Substances that increase the speed of chemical reactions
Are not changed in the reaction
Essential for life
Most are proteins, some are RNA. .

16. Enzymes Lower Reaction Activation Energy

17. Enzymes providing Activation Energy

18. Enzyme Action
Substrate = substance reactant) on which the enzyme acts during a chemical reaction
Active site = the pocket on an enzyme where the substrate fits during a chemical reaction

19. Cellular environment affects enzyme activity
Enzyme activity is influenced by
temperature
salt concentration pH
Reaction rate is affected by amount of substrate

20. ASK QUESTIONS!!!!!