Energy

All chemical processes in the cell require energy.

Both plant and animal cells obtain energy from “ energy-rich” compounds, such as glucose (sugar)

The difference is how plants and animals obtain these compounds.

How do plant and animal cells obtain energy rich compounds?

Plants? Use light to make their

own sugars (Photosynthesis)

Animals? Need to get energy

compounds from their diet.

PhotosynthesisPlants make their own food. This

process is called photosynthesis.

Photo = Light Synthesis = To make Photosynthesis = Make sugar

Where does photosynthesis occur?

Photosynthesis occurs in the leaves of a plant.

Can we be more specific?

Chloroplasts

Photosynthesis occurs in chloroplasts Chloroplasts contain a special substance

called chlorophyll, which makes leaves green

Chlorophyll captures light chemical energy.

The Reaction

carbon dioxide + water glucose + oxygen

Balanced Equation:

6C02 + 6H2O C6H12O6 + 6O2

light energy

chlorophyll

light energy

chlorophyll

Photosynthesis

Why do plants need glucose?

Glucose is the food for the plant. It gives the plant energy to grow.

Glucose

Some is used right away for the cell’s life functions.

Other glucose molecules are stored together to form starch.

Starch and sugar taste different. Think about fresh corn vs. corn that has been

picked and let to sit for a few days.

So you have sugar now what?

Recall: Plants get their glucose from photosynthesis, animals get glucose from their diets.

How do plants and animals then extract the energy from these glucose molecules?

Both types of cells use: Cellular Respiration

Cellular Respiration

Recall: plant and animals both have mitochondria.

Most reactions of cellular respiration occur in the mitochondria.

Mitochondria

The “power-house” of the cell.

glucose (sugar) + oxygen carbon dioxide + water + energy

C6H12O6 + 6O2 6 CO2 + 6H20 + energy

Mitochondria

The Connection

Look at the equations for photosynthesis and cellular respiration.

Any relationships between the two?

energy + 6C02 + 6H2O C6H12O6 + 6O2

C6H12O6 + 6O2 6 CO2 + 6H20 + energy

The products of photosynthesis (C6H12O6 + 6O2) are the reactants for cellular respiration

The products of cellular respiration (6 CO2 + 6H20 ) are the reactants for photosynthesis

Thus we are all connected.

The Connection

Common Misconception

Trees Need Carbon Dioxide Yes!! Humans need Oxygen Yes!! We give one to the other Yes!! Cutting trees would mean less oxygen for us No!! There is a surplus of oxygen for us to breathe, however if we

cut down all the trees then what happens? Increase in the amount of carbon dioxide. This is why we need trees; they are the lungs of the planet.