PHOTOSYNTHESIS

CHEMICAL ENERGY AND ATP

PHOTOSYNTHESIS

• Chemical Energy and ATP– Burning candles can release energy.– Chemical bonds are changed from high energy to

low energy releasing heat and light energy.• One of the principal chemical compounds that cells use

to store and release energy is adenosine triphosphate or ATP.

– Storing Energy• Adenosine diphosphate (ADP)

– A compound that is very similar to ATP, except that it has two phosphate groups instead of three.

PHOTOSYNTHESIS

• This is the way cells store energy.• When a cell has energy available, it can store small

amounts of it by adding a phosphate group to ADP molecules, producing ATP.

– Releasing Energy• How is the energy stored in ATP released?

– The chemical bonds are broken.– ATP has enough energy to power a variety of cellular activities

transport, including active transport across cell membranes, protein synthesis, muscle contraction.

• The characteristics of ATP make it exceptionally useful as the basic energy source of all cells.

ADENOSINE TRIPHOSPHATE

ADENOSINE TRIPHOSPHATE

ADENOSINE TRIPHOSPHATE

ADENOSINE TRIPHOSPHATE

ADENOSINE TRIPHOSPHATE

ADENOSINE TRIPHOSPHATE

ADENOSINE TRIPHOSPHATE

PHOTOSYNTHESIS

• Using Biochemical Energy– Cells carry out active transport using ATP.• The sodium- potassium pump is one way.

– Pumps sodium out and potassium in.

• ATP produces movement of motor proteins that move organelles throughout the cell.

– ATP powers the synthesis of proteins and nucleic acids (store and transmit hereditary, or genetic information) and responses to chemical signals at the cell surface.

PHOTOSYNTHESIS

– Most cells have only a small amount of ATP on hand.

– They can synthesize ATP from ADP, when needed, by using energy in foods like glucose.

• The Photosynthesis Equation– 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

↑light ↘

carbon dioxide + water → sugars + oxygen

PHOTOSYNTHESIS

– Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high energy sugars and oxygen.

– Plants can convert the sugars into starches.• Light and Pigments– How do plants convert the low energy raw

materials into high energy sugars?– How do plants capture the energy of the sun?

PHOTOSYNTHESIS

PHOTOSYNTHESIS

PHOTOSYNTHESIS

PHOTOSYNTHESIS

– In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts.

– Energy from the sun travels to Earth in the form of light.• There are different wavelengths of light.• Some are visible as the visible spectrum and are seen

as colors.

– Plants gather the sun’s energy with light absorbing molecules called pigments.

PHOTOSYNTHESIS

– Chlorophyll is the principal pigment in the plant.– Chlorophyll absorbs the light in the blue-violet and

red regions of the spectrum.– Light is not absorbed well in the green spectrum

and green light is reflected by the leaves, which is why the plants look green.

– Light is energy and the energy that the chlorophyll absorbs is used to make photosynthesis work.

PHOTOSYNTHESIS

PHOTOSYNTHESIS

CELLULAR RESPIRATION

• Overview of Cellular Respiration– Cellular respiration is the process that releases

energy by breaking down glucose and other food molecules in the presence of oxygen.

– 6O₂ +C₆H₁₂O₆ → 6CO₂ + 6H₂O + Energy– oxygen + sugar→carbon dioxide+water + energy– The cells don’t convert and release this energy all

at once. It does it a little bit at a time.

CELL RESPIRATION

COMPARING PHOTOSYNTHESIS AND CELLULAR RESPIRATION

• The energy flows in photosynthesis and cellular respiration take place in opposite directions.– Photosynthesis deposits the energy and cellular

respiration withdraws the energy.– The equations for each are the reverse of each

other.– Photosynthesis removes carbon dioxide from the

atmosphere and cellular respiration puts it back.– Photosynthesis releases oxygen and cellular

respirations uses it.

COMPARING PHOTOSYNTHESIS AND CELLULAR RESPIRATION

• Release of energy by cellular respiration takes place in all eukaryotes and some prokaryotes.• Energy capture by photosynthesis takes place only in

plants, algae, and some bacteria.

COMPARING PHOTOSYNTHESIS AND CELLULAR RESPIRATION

Photosynthesis Cellular Respiration

Function Energy capture Energy release

Location Chloroplasts Mitochondria

Reactants CO₂ and H₂O C₆H₁₂O₆ and O₂

Products C₆H₁₂O₆ and O₂ CO₂ and H₂O

Equation 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ 6O₂ + C₆H₁₂O₆ → 6CO₂ + 6 H₂O