Question

1. What is produced in the light reactions?

2. What occurs in the Calvin Cycle?

Answer 1

ANSWER- Photosynthesis occurs in two phases in chloroplast cell organelle in plants-

• Light reaction
• Dark reaction or calvin cycle

What is produced in the light reactions?

LIGHT REACTION- Light reaction of photosynthesis occurs on thylakoid membrane with the help of photosystem I and photosystem II. A non- cyclic photophosphorylation generally occurs with the photolysis of water to generate ATP and NADPH₂ due to the movement of electrons generated by photolysis of water through Photosystem I and Photosystem II.

• Oxygen is also released as a waste product and ATP and NADPH₂ generated are used in calvin cycle to fix carbon dioxide into glucose. Cyclic photophosphorylation also occurs involving only Photosystem I to generate ATP. Photosystem I has rection center at P₇₀₀ and Photosystem II has rection center at P₆₈₀.

So, in light reaction, ATP and NADPH₂ are produced by photolysis of water along with oxygen as by product.

Cyclic and non cyclic photophosphorylation is shown in the image for the formation of ATP and NADPH and overall reaction is shown only the net reactants used and products formed not with total number of molecules.

* (Activante) Ptoo 700 e Fd ADP+ Pi e CA :-) • ATP light cut bo e ] , ADPAP; ATP cyty e- PSI Ptoo e Po Fd Ferradoxin cyt cyto cytochrome pc> Plastocyanin AOP & Pa Cyclic photo phosphorylation produced from ATP is

Paso Ptoo Pheo 'Ao-A1 PO ares K cyt Complex ates Fd V Light PG NADPH PSTI Pyoo 1680 ATP ADP tri GNADHA PSI NADH2 Mn 447 +02tué Light 2H Non-cyclic photo phosphorylation or P-scheme . بلهنمه بعلمفيد which takes place trylakoid then All Reactions occurs thylator membrane except splitting of inside luman to increase the concentration used for Ht which are Syntresis of All while passing through ATP Synthase. Manganese DQ = Plastoquinone Pheophytin Fd Ferrodoxin. Mnt Pheo Deo Plastocyanin

Overall right Reaction И о + ADP+ P: + NA«Opt. NAPPH, + 97р to2 (by-product)

What occurs in the Calvin Cycle?

CALVIN CYCLE- Calvin cycle is also called biosynthetic phase of photosynthesis which takes place in stroma for the production of glucose from carbon dioxide with the use of products of light reaction, ATP and NADPH₂. Calvin cycle occurs in three phases-

1. Carbon- fixation- In this phase, carbon dioxide is converted into 3-phosphoglycerate by combining with Ribulose-1,5-bisphosphate with the help of enzyme RuBisCO.
2. Reduction- In this phase, 3-phosphoglycerate is converted into glyceraldehyde-3-phosphate with the help of enzyme glyceraldehyde-3-phosphate dehydrogenase.
3. Regeneration- In this phase, Ribulose-1,5-bisphosphate is regenerated with the help of various enzymes.

The purpose of calvin cycle is to fix carbon dioxide to form glucose.

Calvin cycle is shown in the image attached and overall reaction is shown only the net reactants used and products formed not with total number of molecules.

Enzyme Glyceraldehyde-3- Ribulose-1,5-bisphosphate (обок - jiration Сң-о-Ф) (р, 1 С=0 RuBisCo (сион), Р Сн, -0 ② Regeneration 3-Рkерtо учиat. Е. е Calvin 44 1 Онон Various Enzymes ш, -о-Ф are involved © Reductions P7Р ADDTPE те, NADPH NAOPY glyceraldehyde 3-phosphate 앤 phosphate dehydrogenase CHO (кон н, -о-) Various Reaction f -Н (CHOH) Киев и, ои

Overall Dark Reaction Og + ATP & MARPHg Ташкез- phosphate t ADP + Pi + Naopt