Cell Energy

Photosynthesis and Respiration

Photosynthesis

•Photosynthesis- process by which plants & certain other organisms use sunlight to make sugar

•Energy conversion- solar energy food (sugar)•Takes place in chloroplasts containing chlorophyll (green pigment in cells)

Sources of Energy

• Nearly all living things obtain energy either directly or indirectly from the energy of sunlight captured during photosynthesis.• Autotrophs-organism that make its own

food

• Heterotrophs-organism that cannot make its own food; obtain food by eating other organisms or absorbing their food.

Stages of Photosynthesis

• 1. Sunlight is captured by chlorophyll, this happens during the day.• Chlorophyll acts like the solar cell of a

calculator.

• 2. Energy is used to make food or manufacture sugar; this can happen during the day or at night.

Ingredients of Photosynthesis

• Raw Materials:• H2O (water), absorbed through the roots

• CO2 (carbon dioxide) gas enters through stomata (small hole) in leaves

• Products:• C6H12O6 (sugar), uses the energy to carry out

important cell functions.

• O2 (oxygen), exits through the stomata

Formula

sunlight

6 CO2 + 6 H2O --- C6H12O6 + 6 O2

chlorophyll

Oxygen-Carbon Dioxide Cycle

• Gases are exchanged between organisms

-------- CO2

O2 -----

What is Cellular Respiration?

• Respiration is the process by which cells obtain energy from glucose.• Cells break down simple food molecules, like

sugar and release the energy they contain.

• Energy stored in cells is like money in a savings account; you can withdraw it as needed.

• Why would plants need to use stored energy during the winter months?

Stages of Aerobic Respiration

1. First stage takes place in the cytoplasm of cells. Molecules of glucose (sugar) are broken down into smaller molecules. Oxygen is not involved, little energy released.

2. Second stage takes place in mitochondria, the “powerhouse.” Here the small molecules are broken down even smaller.

Respiration

Formula for respiration:•C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP (energy)

Photosynthesis and respiration are opposites of each other.• 6 CO2 + 6 H2O --- C6H12O6 + 6 O2

Fermentation

• Provides cell with energy without using oxygen

• Yeast and other single-celled organisms break down sugar and in the process energy is released.

• Products = CO2 + alcohol + ATP (energy)

• Beer, wine, bread are produced with yeast

Lactic Acid Fermentation• Sometimes the need of

muscles for energy is greater than the ability to obtain oxygen.

• When this happens, muscles use fermentation to get energy and you may feel tired and sore.