Light indepdent reaction Flashcards
What are the products of light-dependent reaction
e.g ATP and reduced NADP used in light independent reaction?
To reduce glycerate 3-phosphate in the second stage of photosynthesis
Why is light independent reaction different from light-dependent reaction?
Does not require light directly and in theory occurs whether light is available or not
What does it require?
The products of light-dependent stage and so rapidly cases when light is absent
Where does it take place?
In the stroma of the chloroplasts
What is the details of this stage worked out by?
Melvin Calvin
e.g
Calvin Cycle
What is the first step of light independent (LIR)?
- The carbon dioxide from the atmosphere diffuses into the leaf through the stomata
- It dissolves in water around the walls of the mesophyll cells
- It diffuses through the cell-surface membrane, cytoplasm and chloroplast membrane into stroma of the chloroplast
What is the second step of lihgt independent reaction?
- In the stroma, carbon dioxide reacts with 5-carbon compound of RuBP
- A reaction catalysed by an example called rubsico
What is the full name of RuBP?
Ribulose Bisphosphate
What is full name of rubsico?
Rublose bisphosphate carboxylase
What is the third stage of light independent reaction?
The reaction between carbon dioxide and RuBP produces two molecules of 3-carbon GP
What is full name of GP?
Glycerare 3-phosphate
What is fourth stage of light independent reaction?
Reduced NADP from LDR is used to reduce GP to TP using energy supplied by ATP
What is the full name of TP?
Triose phosphate
What is the fifth step of LIR?
NADP is re-formed and goes back to the LDR reaction to be reduced again by accepting more protons
What is the sixth step of LIR?
Some TP molecules are converted to organic substances that plant requires such as starch, cellulose, lipids, glucose , amino acids and nucleotides
What is the seventh step of LIR?
Most TP molecules are used to regenerate RP using ATP from LDR
What proportion of TP is used to regenerate RuBP?
5/6
(1/6 - used to make organic molecules)
Why Calvin Cycle needs to turn six times to make one hexose sugar?
- Three turns of cycle produce six TP because 2 TP made for one CO2 used
- 5/6 of TP used to regenerate RuBP
- Three turns of cycle only one TP is produced thats for hexose sugar
- A hexose has six carbons , two TP need to form one hexose sugar
- Cycle turn six times to make two molecules of TP used to make sugar
- Six out of the cycle need 18 ATP and 12 NADPH from LDR
What keeps the cycle going?
Make sure there is enough RuBP
ready to combine with CO2 in atmosphere
Diagram of Calvin Cycle
Diagram of total no in Calvin Cycle
What is carbon fixation?
Addition of C02 to RuBP
What is Calvin cycle the starting point for?
Making all organic substances a plant needs
Tp and GP molecules are used to make carbohydrates, lipids and amino acids?
How are carbohydrates made?
Hexose sugar e.g glucose
Joined two TP molecules together
Larger carbohydrate made (e.g sucrose, cellulose) by joining hexose sugar in different ways
How are lipids made?
Made from using glycerol which is synthesised from TP and fatty acids which are synthesised from GP
How are amino acids made?
Some are made from GP
How is the fluid of the stroma adapted for LIR?
It is membrane bound in the chloroplast
Chemical envirnoment has high concentration of enzyme and subtrates be maintined within it
Distinct from the envirnoment of the cytoplasm
How is the stroma fluid surrounding grana adapted?
Products of LDR reaction in grana can readily diffuse in the stroma
How chloroplats containg DNA and ribosomes adapted for LIR?
Quickly manfacture some proteins involed in LIR
