1. Bellwork: What do cells need energy for
Bellwork: What do cells need energy for? Where does this energy come from?

2. Chapter 8: Photosynthesis
Section 8.1 – Energy and life

3. What is ATP?
ATP and it’s sister molecule ADP are compounds that play a very important role in providing energy for a cell’s day to day functions.

4. Why is ATP useful? ATP acts an energy store/source for the cell
Cells can store energy in ATP when they have excess energy
Cells can release energy from ATP when the cell is in need

5. How does ATP release energy?
Cells can release the energy stored in ATP by the controlled breaking of chemical bonds between the second and third phosphate group

6. Difference between ADP and ATP

7. What is the energy used for?
Active transport
Pumping across a cell membrane against a concentration gradient
Powers cell movement
Contraction of muscles – e.g. the heart
Protein synthesis
Various other functions
Producing light in fireflies

8. Why don’t cells stockpile ATP?
Cells only have enough ATP to last a few seconds
Why? It is not an effective store of energy over a long time
Sugars such as glucose are much more effective long term stores of energy
One glucose molecule stores 90 times the energy required to make one ATP molecule
Storing energy as sugar is much more efficient
ATP can be generated as and when it is needed
Transferring energy for specific uses is easier from ATP

9. Where does the energy come from?
Heterotrophs – food
All animals and fungi
Autotrophs – are able to generate their own food
All life on earth depends on Autotrophs
They can harness the sun’s energy and produce carbohydrates
Sugars and starches
Photosynthesis!
Light energy from the sun is converted into chemical energy

10. History of research on photosynthesis
1643 – Jan Van Helmont notice plants take up water and this contributes to their weight
Joesph Priestly used a bell jar, plant and candle to show that plants produce oxygen
1779 – Jan Ingenhousz showed that aquatic plants produce oxygen bubbles in the light but not the dark
1845 – Julius Robert first proposed that plants convert light energy into chemical energy
1948 – Melvin Calvin traces the path of Carbon in the formation of glucose
1992 – Rudolph Marcus wins Nobel prize for work on electron transport chain
2004 – So Iwata and Jim Barber describe how water molecules split during photosynthesis