The Cell in Action

Cell EnergyPhotosynthesis

Cellular RespirationFermentation

Cells Need Energy • Cells of all organisms need energy to

– Carry chemical activities of the cell– Reproduce– Grow– Live

• Where does this energy come from?

What Is Photosynthesis?• Photosynthesis is the process by which a cell

captures the energy in sunlight and uses it to make food.

• Photo = light & synthesis = put together

• Photosynthesis occurs inside chloroplast in the cells of plants and algae.

Where in plants are cells with many chloroplasts found?

• Chloroplasts are green organelles inside plant cells.

Plant Cell

Chloroplast

Mitochondria

Chloroplast Traps the Sun’s Energy

• This energy-capturing process occurs in the leaves, and other green parts of the plant that contain chloroplast.

• This energy is then transferred to chlorophyll, a green pigment inside chloroplast.

• Chlorophyll gives plants their green color.

Photosynthesis

Photosynthesis • The energy captured by chloroplast drives

the second stage of photosynthesis.• At this stage, plants use:

– Carbon dioxide CO2 (a gas in the air)– Water H2O (absorbed by roots from soil)– Sun’s energy

• Carbon dioxide CO2 enters the plant through small openings on the leaves called stomata.

• Once in the leaves, water and carbon dioxide move to chloroplast.

The Photosynthesis

Equation

6 CO2 + 6 H2O → → → → → → C6H12O6 + 6 O2Light Energy

Cellular Respiration • Cellular respiration is the process of

converting nutrients such as carbohydrates, proteins, and lipids into glucose.

• In both plants and animals, cellular respiration takes place in the mitochondria.

• In cellular respiration glucose and oxygen combine to produce energy in form of ATP, water, and carbon dioxide.

Photosynthesis & Cellular Respiration

Photosynthesis & Cellular Respiration• Plants do both photosynthesis and

respiration. This means that plants are the only organisms that can make their own food. Hence, they are called producers.

• Animals can only make energy by eating other organisms. So, they are called consumers.

Cellular Respiration Equation

• C6H12O6 + 6 O2 → → → 6 CO2 + 6 H2O + ATP

•glucose + oxygen → → → carbon dioxide + water + energy