GEN BIO 1 | Photosynthesis (Calvin Cycle)

Calvin Cycle

Uses ATP and NADPH to build sugar molecules out of carbon dioxide

Calvin Cycle Inputs

ATP, NADPH, and CO2

Calvin Cycle Output

Glyceraldehyde-Phosphate, or G3P, a precursor to many carbohydrates

Steps of Calvin Cycle

1. CO2 Fixiatuon

2. CO2 Reduction

3. Regeneration of RuBP

Carbon Fixation

Three CO2 enters the cycle one at a time. CO2 attaches to a 5-carbon sugar with two phosphate groups called ribulose biphosphate (RuBP) through the rubisco enzyme to form a 6 molecule sugar. Oxygen leaves as a waste product

3-Phosphoglycerate

Since the six molecule is unstable in halves into 2 PGA for six in total.

CO2 Reduction

The PGAs receive an additional phosphate group from ATP becoming a 1,3-biphosphoglycerate. Since there are 6 PGAs, then there will be 6 ATPs for six 1,3-biphosphoglycerate

NADPH in Reduction

It gives off an electron to convert the 1,3-biphosphoglycerate into G3P. The NADPH turns into the NADP+ The only one exits the cycle to be a precursor to the carbohydrates while the five are used in the cycle and rearranged into RuBP (15 carbon molecules)

Regeneration of RuBP

To complete the cycle, it spends 3 more ATP molecules to give a phosphate group. RuBP is now prepared to receive CO2 again and cycle continues

How many ATP were used in total, which in turn produced how many ADP were produced?

nine, six in fixiation and three in regenration

How many NADPH were used in total, which in turn produced how many NADP+ were produced?

six

Fate of G3P

it can be converted into sucrose, starch, and cellulose and fatty acid synthesis into triglyceride