1. Chapter 8
Cellular Energy

2. How Organisms Obtain Energy
Energy = ability to do work
Thermodynamics = study of the flow and transformation of energy
1st Law: energy CANNOT be created or destroyed only changed
2nd law: energy cannot be changed without the loss of usable energy.

3. Autotroph = make
Their own food/energy
Heterotroph= consume
other organisms for food/energy
Chemoautotrophs = consume inorganic matter for energy

4. Metabolism - ALL chemical reactions
of the cell
Metabolic Pathway = process where
the product of one reaction
is used as the reactant
for the next reaction.
(Like a chain reaction!!)
There are 2 types ….

5. (1)Anabolic - uses energy to BUILD UP large molecules
Example - Photosynthesis =
sun’s light energy (reactant) is converted into chemical energy (product)
Takes smaller molecules
(carbon dioxide and water)
to make bigger molecules
(sugar and oxygen)

6. (2)Catabolic - releases energy to BREAK DOWN large molecules into small molecules
Example - Cellular respiration =
organic molecules (products from
photosynthesis) are the
reactants broken down to
RELEASE ENERGY for use
by the cell
Take big molecules
like sugar and oxygen)
and break down into
smaller ones (like CO2
and water)

7. ATP: The Unit of Cellular Energy
ATP releases energy when the bond between the 2nd and 3rd phosphate groups is broken.
This forms a molecule called ADP (adenosine diphosphate), energy and a free phosphate group
Breaking the bond releases mechanical energy

8. ATP Continued
An ATP molecule can be compared to a fully charged battery
When the bond between the 2nd and 3rd phosphate breaks, it loses some energy, becoming ADP
ADP could then be compared to a partially charged battery

9. Photosynthesis – Light energy is trapped and converted into chemical energy in Autotrophs.
Reaction:
6 CO2 + 6 H2O >>> C6H12O6 +6 O2
Chloroplasts & Pigments are used to capture light energy
Anabolic Process

10. Photosynthesis continued….
Chloroplasts: found mainly in cells of leaves because of the large surface area.
Pigments: Light absorbing color molecules found in thylakoid
Chlorophyll: most abundant pigment found in plants.

11. Cellular Respiration Catabolic Process
Process by which organisms obtain energy by breaking down organic molecules.
Formula:
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
C6H12O6 (product from photosynthesis)
Catabolic Process

12. Two kinds of Cell Respiration
Anaerobic Respiration/Fermentation:
Does not require oxygen to complete
Produces only 2 ATP
Lactic Acid Fermentation causes muscle fatigue in animals
Ethanol fermentation is used in bread and wine making

14. Aerobic Respiration This kind of respiration does require oxygen
Produces 36 ATP!!!
Composed of two different parts
The citric acid cycle
The electron transport chain

16. Photosynthesis vs Cellular Respiration Differences
Anabolic Process
Reactants: CO2, Water, Light
Products: Glucose and Oxygen
Happens in Plants Only!
Traps energy (light)
Happens in Chloroplasts
Cellular Respiration
Catabolic Process
Reactants: Glucose and Oxygen
Products: CO2, Water, Energy
Happens in Plants and Animals!
Releases energy (ATP)
Happens in Mitochondria

17. Photosynthesis and Cellular Respiration Similarities
Both are part of a metabolic pathway
Both reactions transfer energy
Products of Photosynthesis are the reactants of Cellular Respiration