Light independent Flashcards
1
Q
Describe carbon fixation
A
First reaction: CO2 is added to ribulose 1, 5-bisphosphate (RuBP), a 5-carbon molecule, to form a 6-carbon intermediate
* This 6-carbon intermediate splits into two 3-carbon molecules of 3-phosphoglycerate (PGA)
* This first reaction occurs 3 times to produce 6 molecules of PGA
* All reactions in this phase are catalyzed by the enzyme rubisco.
2
Q
Describe reduction & oxidation reactions – for the ‘key players’
A
- P680: Gets oxidized (loses electrons) and needs new ones, so it splits water to get electrons.
- P700: Also gets oxidized and sends electrons to the primary electron acceptor, which eventually helps produce NADPH.
- Primary Electron Acceptors: Receive electrons from P680 and P700, helping start the electron transport chain (ETC).
- Cytc (Cytochrome complex): Acts like an electron shuttle, moving electrons along the ETC.
- PQ (Plastoquinone): Loses electrons (oxidizes) and transfers them along the ETC.
- NADP+ Reductase: Accepts electrons and reduces NADP+ into NADPH, which is used for energy.
- Ferredoxin: Transfers electrons in the ETC through redox (electron transfer) reactions.
- Water (H₂O): Splits and donates electrons to P680, releasing oxygen as a byproduct.
- Photons (Light): Excite P680 and P700, causing them to lose electrons and start the chain.
3
Q
Why is Rubisco considered one of the most important enzymes on Earth?
A
it helps in the making of organic molecules that are consumed by many of the world’s organisms
4
Q
Describe how RuBP is regenerated
A
- G3P, a 3-carbon molecule, leaves the Calvin cycle.
- The remaining 15 carbons are rearranged.
- ATP and water help transform these carbons.
- This process forms three molecules of RuBP.
- RuBP is now ready to capture more CO₂ and keep the cycle going.