Could you run through the stages in the light-independent reaction (Calvin Cycle) of photosynthesis?

Okay, so here we have what seems like a very daunting​ list of chemical reactions to remember that don't seem to make any sense! But don't worry​, with practice you will soon grasp the concept quickly.

Location

The first​ thing you need to remember is where this reaction takes place. This reaction takes place within a fluid known as the​ stroma​ in a structure called a ​chloroplast​ inside a leaf.

Stages of Reaction

1) All plants need ​CO2​ for photosynthesis.​ This is our first step. CO2 enters the leaf through the stomata and diffuses into our liquid stroma.

2) Next, this CO2 is combined with a 5-carbon compound called ribulose biphosphate (RUBP) forming an unstable 6 carbon compound. ​This is catalysed by an enzyme called rubsico.

​3) Since it is unstable, this 6 carbon compound quickly breaks down into two molecules of a 3-carbon compound called ​glycerate-3-phosphate.

​4) ​ATP and reduced NADP (from the light-dependent reaction) ​then reduce our glycerate-3-phosphate into a different 3-carbon compound called triose phosphate. (TP)

​5) This is the product we've been after. Two things can then happen once we have ​TP:​ it can either be used to produce hexose​ (six carbon) sugars such as ​glucose, ​or go back into the cycle to ​regenerate RUBP ​so that more CO2 can combine with it and the cycle can begin anew.

So in summary:

1) CO​2 ​enters stomata and diffuses into stroma.

2) CO2​ + RUBP = unstable 6-C compound

3) 6-C breaks into x2 of G-3-P

4) ATP + Reduced NADP then reduce G-3-P into TP

5) TP either makes useful substances such as glucose or regenerates RUBP.

Any more questions, feel free to drop a message.

 

Answered by Shane C. Biology tutor

2735 Views

See similar Biology A Level tutors

Related Biology A Level answers

All answers ▸

Explain how partial pressure of oxygen affects how oxygen binds to haemoglobin in different areas of the body.


How do electrical impulses control contraction of the heart?


Describe the process of DNA replication


Describe the process of ultrafiltration in the Kidneys.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences