Photosynthesis & Cellular Respiration Cell Functions Photosynthesis & Cellular Respiration

Autotrophs & Heterotrophs Plants and some other types of organisms are able to use light energy from the sun to produce food The sun is the ultimate source of energy on Earth Autotroph? Heterotroph?

Autotroph or Heterotroph?

Chemical Energy & ATP One of the main compounds used by living things to store energy is ATP What does ATP stand for? Cells can store energy by adding a phosphate to ADP to make ATP

Releasing energy The energy stored in ATP is released when ATP is converted back to ADP and a phosphate group The characteristics of ATP make it an exceptionally useful molecule that is used by all types of cells in their basic energy source

ATP and Glucose Even though ATP is efficient at transferring energy, it is not good for long term storage Cells can regenerate ATP from ADP as needed by using the energy in carbohydrates like glucose

Think About it Why do we need to eat? Think about ATP…

Investigating Photosynthesis 1643—Jan Van Helmont After careful measurements of water intake and weight increase, he concluded that trees gain most of their mass from water 1771—Joseph Priestley Using a bell jar, a candle, and a plant, Priestley found that the plant releases a substance that keeps the candle burning—a substance that we now know is oxygen

Investigating Photosynthesis 1779—Jan Ingenhousz Ingenhousz found that aquatic plants produce oxygen bubbles in the light but not in the dark. He concluded that plants need sunlight to produce oxygen

Photosynthesis Photosynthesis is the process by which plants take light energy and turn it into chemical energy 6H2O + 6CO2 C6H12O6 + 6O2 Light

Light & Pigment In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts Sunlight (“white” light) is actually a mixture of different wavelengths of light—visible color spectrum

Inside a Chloroplast Photosynthesis takes place inside the chloroplast Chloroplasts contain pancake-like structures called thylakoids Thylakoids contain chlorophyll and other pigments known as photosystems that are able to capture light energy

Chloroplast

Chloropyll Plants absorb the sun’s light energy with light- absorbing molecules called pigments The main pigment in plants is called chlorophyll There are two kinds of chlorophyll, a and b

Photosynthesis Photosynthesis can be broken down into 2 parts: Light Dependent Reaction Takes place in the thylakoid Calvin Cycle (light independent reaction) Takes place in the stroma

Light dependent Reactions Photosystem II Electron Transport Chain Photosystem I ATP Formation

Photosystem II Light is absorbed by chlorophyll or other pigments in photosystem II The energy from the light is transferred to electrons, which are then passed on the electron transport chain. Separately, enzymes break up water molecules into electrons, hydrogen (H+), and oxygen