Energy Transformation 1
- Energy is captured and put into biosphere through photosynthesis
- Measure of chlorophyll concentration is equal to number of photosynthetic
- 50% terrestrial 50% aquatic photosynthesis.
- Temp has little to do with oceanic photosynthesis
- Carbon dioxide converted to glucose for photosynthesis.
- This is possible because they use energy from light to drive reduction of CO2
- Reason they use glucose because it has a lot of free energy.
- No energy in CO2, can’t get anything out of CO2, no electrons you can get.
Oxygen is holding on to them too tight.
- C-H bonds are what we need, lots of energy in the molecule, lots of free
electron that can be easily removed.
- Endergonic process, free energy of products is greater than reactants.
Anabolic pathways, overall positive change in free energy.
- Water gets oxidized to oxygen. Carbon dioxide gets reduced to glucose.
- Photosynthesis can be divided into two parts:
~ Light reactions: producing ATP energy and reducing power in the form of
NADPH. NADPH gives up electrons.
~ Calvin cycle: CO2 converted to carbohydrate glucose.
- Highly conserved
- Outer and inner membrane
- Stroma: aqueous compartment filed with enzymes
- Interior membrane organization: thylakoid membrane
- Calvin cycle takes place in stroma
- Thylakoid is where light reactions take place.
- In thylakoid: thylakoid lumen
- There is noting uniquely eukaryotic about photosynthesis.
- Happened well before eukaryotes formed.
Photosynthetic Electron Transport:
- In thylakoid membrane
- Large supra complexes (protein complexes)
- Many proteins come together to make photosystem 1 and 2 and cytochrome
- Both PS2 and PS1 have a reaction center surrounded by antenna, chlorophyll
molecules in antenna and light gets funneled to reaction entre. The reaction
center chlorophyll of PS2 is P680 and of PS1 Is P700. - Photosystem 1 and 2 absorb a photon of light, light is funneled to reaction
centers, chlorophylls get oxidized (photochemical event) electron from P680
leaves and travels down electron transport chain to PS1.
- Big pool of PQ molecules in membrane to shovel electrons.
- PQ would fall apart if too fluid, too rigid, PQ would have trouble travelling
- P680 is oxidized, gets electron from splitting of water.
- When PQ picks up electron from PS2 it becomes negatively charged, hard
time to go through membrane, then picks up proton from stroma now
- Proton gets dropped in thylakoid membrane.
- pH of lumen becomes very low compared to that of stroma.
- Electrochemical gradient created. Can do work with this gradient. Can
harvest gradient to do work. Chemiosmosis is how we harvest an
electrochemical gradient to do work.
- Only way for protons to get back across, must move through ATP synthase