1. Cell Processes and Energy

2. Organisms Require Energy
Two organelles are responsible for providing energy to living things:
Chloroplasts
Mitochondria

3. Chloroplasts
Found mainly in plant cells.
The site of photosynthesis

4. Photosynthesis
The process by which a cell captures energy in sunlight and uses it to make food.
Photo = light Synthesis= putting together
Photosynthesis means using light to make food

5. Photosynthesis is a two stage process Stage One
Capturing the sun’s energy
Takes place in the Chloroplasts
Pigments (chlorophyll and others) capture the light energy and use it to power the second stage (similar to solar cells powering a calculator)

6. Photosynthesis - Stage Two
The second stage also takes place in the chloroplast
Water (H2O) and Carbon Dioxide (CO2) undergo a series of chemical reactions.
*Water enters a plant through its
roots.
*Carbon dioxide enters the plant through the stomata ( tiny
openings in the leaves)

7. The Chemical Reaction The chemical reactions are powered
by energy from the sun.
The atoms in carbon dioxide and water are separated and joined to form
oxygen and glucose (a simple sugar)
light energy
6CO2 + 6H2O  C6H12O6 + 6O2
carbon dioxide + water yields glucose oxygen
raw materials products

8. Storing Energy During the process of photosynthesis
the cell stores energy in glucose (sugar)
*Some of the glucose is used as food
*Some is converted into other
molecules, such as cellulose.
*Some is stored for later use

9. Mitochondria
When the cell or organism needs energy, the mitochondria go to work.
The process by which cells break down simple food molecules to release energy is called respiration

10. Respiration is also two stage process.
Stage one occurs in the cytoplasm,
where glucose molecules are broken
down into simpler forms. A small
amount of energy (ATP) is released

11. Respiration - Stage Two
Stage two takes place in the mitochondria. Oxygen is required for this stage and a large amount of energy (ATP) is released.

12. Respiration Equation
C6H12O O2  6CO H2O
Glucose Oxygen Yields Carbon Water + Energy(ATP)
Dioxide
Notice the equation is opposite that of photosynthesis
Together the two process keep the levels of CO2 and O2 fairly constant

13. Fermentation
Some cells are able to obtain energy from food without using oxygen.
This process is called fermentation.
Less energy is released when oxygen is not used.
There are two types of fermentation
* Alcoholic Fermentation
* Lactic Acid Fermentation