Photosynthesis and Respiration CELL ENERGY Photosynthesis and Respiration

What are the green organelles inside the leaf cells?. What is the function (job) of the chloroplast?

Chemical Energy and ATP Energy = ability to do work Energy comes in different forms (light, heat, electricity) Cells need energy to do work Cell energy comes from ATP (adenosine triphosphate) Consists of adenine, a 5-carbon sugar and THREE phosphates Phosphates are the key to ATP’s ability to store and release energy

Examples of ATP in action Active transport Protein pumps in cell membrane need ATP Movement Muscle contractions Protein synthesis

Storing and Releasing Energy Cells release energy from ATP when the bond between the second and third phosphate groups is broken Phosphate released = energy released ATP minus a phosphate group = ADP

Storing and Releasing Energy ADP (adenosine diphosphate) can be recharged by adding another phosphate group to become ATP again Phosphate gained = energy stored Cells regenerate ATP from ADP by using energy in food like glucose

Quick Check Where is the energy stored in the molecule of ATP? How would you change the figure to show a molecule of ADP?

What is the connection between the food you eat and ATP? Cells do not keep a lot of ATP Food is digested and converted into ATP Different foods give different amounts of ATP Carbohydrate = 36 ATP Lipid = 146 ATP Proteins = broken down to make other proteins, not energy!!!! Plants use photosynthesis to produce the carbs so their cells can get ATP

LIGHT Energy Mixture of different wavelengths (color) Can be absorbed, transmitted or reflected Absorbed energy can be used for photosynthesis Reflected light is not used for photosynthesis Absorbed by pigments (chlorophyll) in plant cell chloroplasts

Quick Check…look at the light absorption spectrum on the previous slide What color light is least absorbed? What color(s) of light are most absorbed? What color of light can be used for photosynthesis? How would a plant grow if only given green/yellow light?

CHLOROPLASTS

CHLOROPLASTS Thylakoids = photosynthetic membranes (contain chlorophyll) Arranged in stacks called grana Stroma = space around the thylakoids

High-Energy Electron Carriers Chlorophyll absorbs light Absorption of light produces high-energy electrons Electrons picked up by NADP+ to become NADPH NADPH carries the high-energy electrons to chemical reactions elsewhere in the cell

Photosynthesis – BIG PICTURE Multi-step process Energy from the sun is used to convert water and carbon dioxide (reactants) into high energy sugars and oxygen (products Plants then use the sugars to make ATP (cell respiration…stay tuned)

Photosynthesis - Details Light dependent reactions INPUT= sunlight, water, chlorophyll OUTPUT = oxygen (waste), ATP, energy carriers (NADPH) LOCATION = thylakoid

Photosynthesis - Details Light Independent reactions (a.k.a. Calvin Cycle) INPUT– carbon dioxide, energy carriers from light reactions OUTPUTS – sugar (carbohydrate) and water LOCATION - stroma