July 31, 2021
In this IBDP Biology blog post, we will learn:
- The recap of photosynthesis
- The detailed process of the Calvin cycle
Photosynthesis
Photosynthesis: Is a metabollic pathway. Carbon dioxide along with water is used to produce carbohydrates. Oxygen is released as a waste gas
6CO2 + 6H2O _______________ C6H12O6 + 6O2
Photosynthesis occurs in a Chloroplast
Stroma: Light independent reactions
- 70S ribosomes and naked DNA
Thylakoid membranes: Light dependent reactions
- Starch grains and oil droplets are products of photosynthesis and acts as chemical energy stores
Steps of the Calvin cycle
- RuBP a 5 carbon compound binds to an incoming carbon dioxide molecule in a process called carbon fixation.
- This fixation is catalysed by the enzyme Rubisco. The result is an unstable 6 carbon compound
- The unstable 6 carbon compound breaks down into two 3-carbon compounds called glycerate 3 phosphate
- The 3 carbon molecules of GP are acted upon by ATP and NADPH from the light dependent reacton to form two other 3 carbon molecules called Triose Phosphate. This is a reduction reaction
- The molecules of TP may go in either two directions. Some leave the cycle to become sugar phosphates that may become more complex carbohydrates.
- Most however continue in the cycle to reproduce the origniating compound of the cycle RuBP
- In order to regain RuBP molecules from TP the cycle uses ATP
That's all!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.khanacademy.org%2Fscience%2Fap-biology%2Fcellular-energetics%2Fphotosynthesis%2Fa%2Fcalvin-cycle&psig=AOvVaw2xySy-1I7cbSgr7PeaqPrq&ust=1627830509807000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCMCk2azLjfICFQAAAAAdAAAAABAD
Drafted by Venetia (Biology)