Light dependent stage Flashcards
What are the two distinct stages of photosynthesis?
Light-dependent reactions and light-independent reactions
Where do the light-dependent reactions take place?
Across the thylakoid membrane
Where do the light-independent reactions occur?
In the stroma
What is the process called that involves the splitting of water molecules during the light-dependent reactions?
Photolysis
What are the products of photolysis of one molecule of water (H2O)?
- 2 hydrogen ions (2H+)
- 2 electrons (2e-)
- 1 atom of oxygen (O)
What is the role of NADP in the light-dependent reactions?
To accept Hydrogen ions and electrons and get reduced to NADPH
What happens to NADP when it gains hydrogen?
It is reduced to form reduced NADP or NADPH
Define reduction in the context of NADP.
Gain of electrons, gain of hydrogen, or loss of oxygen
Define oxidation in the context of NADP.
Loss of electrons, loss of hydrogen, or gain of oxygen
What are the useful products of the light-dependent reactions?
- ATP
- NADPH
- Oxygen (waste product)
What is photophosphorylation?
The process of producing ATP from ADP through the addition of phosphate using light energy
What are the two types of photophosphorylation?
- Non-cyclic photophosphorylation
- Cyclic photophosphorylation
What does non-cyclic photophosphorylation produce?
Both ATP and NADPH
What does cyclic photophosphorylation produce?
ATP only
What is the function of the electron transport chain in the light-dependent reactions?
To transfer electrons and release energy
What is chemiosmosis?
The process where H+ ions are pumped to generate a concentration gradient, driving ATP production
What happens to electrons after they leave photosystem II?
They pass to the first protein in the electron transport chain
and is accepted by Ps i
How are H+ ions generated during the light-dependent reactions?
By the photolysis of water
What catalyzes the production of ATP during chemiosmosis?
ATP synthase enzymes
What happens to the excited electrons from photosystem I?
They pass along another electron transport chain and form reduced NADP with hydrogen ions
What is the equation for the formation of NADPH?
H+ + 2e- + NADP+ → NADPH
What is the cycle in cyclic photophosphorylation?
Electrons rejoin photosystem I after passing through the electron transport chain
True or False: Non-cyclic photophosphorylation involves only photosystem I.
False
Fill in the blank: The light-dependent reactions produce ATP, NADPH, and _______.
Oxygen
