Cells and Energy
• How does a cell obtain energy?
• How do some cells make food molecules?

Photosynthesis

The primary need of all cells is energy.
Sun-the ultimate source of energy used by living things

Some organisms are capable of absorbing light energy and converting it into stored chemical energy. This process is called photosynthesis.

Photosynthesis is a series of chemical reactions that convert light energy, water, and CO
2 into the food-energy molecule glucose and give off oxygen.
photosynthesis from Greek photo , means “light”; and synthesis , means
“composition”

Photosynthesis is one of the most important biological processes - because it is the essential step between solar energy and life.

This process combines carbon dioxide, water, and light energy to form glucose (a sugar) and oxygen.

For photosynthesis to occur, special pigments, organelles, and enzymes must be present.
Pigments are colored substances that absorb light energy.

•
The chemical reactions of photosynthesis are powered by light energy.
•
In the chloroplasts of plants, pigments such as chlorophyll absorb light energy
•
Chlorophyll absorbs all colors except green light, which is reflected as the green color in leaves.

In order for photosynthesis to happen, catalysts must be present. chlorophyll (a greencolored pigment) the primary catalyst of photosynthesis; most chlorophyll is located in chloroplasts

In addition to chlorophyll, plants and algae have other pigments
(red, pink, yellow, brown, etc.) that also absorb light energy and may pass the energy on to chlorophyll.

Photosynthesis Equation
Carbon dioxide + water
+ light energy -----> glucose + oxygen + water

•
When an organism eats plant material it takes in food energy from the plant’s glucose.
• An organism’s cells use the oxygen released during photosynthesis and convert the food energy into usable energy through cellular respiration.

Enzymes