Surviving on Photosynthesis

These flashcards cover key vocabulary and definitions related to photosynthesis and its processes.

Photosynthesis

A metabolic pathway that uses light energy to convert carbon dioxide and water into glucose and oxygen.

Thylakoids

Membrane-bound structures within chloroplasts that host the light-dependent reactions of photosynthesis.

Light-dependent reactions

The part of photosynthesis that converts light energy into chemical energy (ATP and NADPH) while splitting water and releasing oxygen.

Photolysis

The process of using light energy to split water molecules into oxygen, protons, and electrons during photosynthesis.

Photosystems

Molecular arrays of chlorophyll and accessory pigments that capture and convert light energy into chemical energy.

Chemiosmosis

The process by which ATP is produced across the thylakoid membrane due to the movement of protons down their concentration gradient through ATP synthase.

Calvin Cycle

The series of biochemical reactions that occur in the stroma of chloroplasts, using ATP and NADPH to convert carbon dioxide into glucose.

Electron transport chain

A series of protein complexes in the thylakoid membrane that transfer electrons and pump protons to generate a proton gradient for ATP synthesis.

NADP+

A coenzyme that forms NADPH when it accepts electrons and protons during the light-dependent reactions.

Chlorophyll

The green pigment in plants that absorbs light energy, primarily in the blue and red wavelengths.

Plastoquinone

A mobile electron carrier in the thylakoid membrane that transfers electrons from Photosystem II to the cytochrome complex.

Plastocyanin

A copper-containing protein that transfers electrons from the cytochrome complex to Photosystem I.

Cytochrome complex

A protein complex in the thylakoid membrane that pumps protons into the lumen while transferring electrons between plastoquinone and plastocyanin.

Ferredoxin

An iron-sulfur protein that accepts electrons from Photosystem I and donates them to NADP+ reductase.

NADP reductase

An enzyme that catalyzes the reduction of NADP+ to NADPH using electrons from ferredoxin, a key step in the light-dependent reactions.

What is the primary function of the Calvin Cycle?

To convert carbon dioxide from the atmosphere into glucose, using the ATP and NADPH produced during the light-dependent reactions.

Where does the Calvin Cycle take place?

In the stroma of the chloroplasts.

What are the three main phases of the Calvin Cycle?

1. Carbon fixation

2. Reduction

3. Regeneration of RuBP (Ribulose-1,5-bisphosphate)

What happens during the "Carbon fixation" phase of the Calvin Cycle?

Carbon dioxide is incorporated into an organic molecule, specifically by attaching to RuBP (Ribulose-1,5-bisphosphate), forming an unstable 6-carbon intermediate that immediately splits into two molecules of 3-PGA (3-phosphoglycerate).

What enzyme catalyzes the carbon fixation step in the Calvin Cycle?

RuBisCO

What happens during the "Reduction" phase of the Calvin Cycle?

3-PGA molecules are converted into G3P (Glyceraldehyde-3-phosphate) molecules using ATP and NADPH from the light-dependent reactions.

What happens during the "Regeneration" phase of the Calvin Cycle?

Most of the G3P molecules are used to regenerate RuBP (Ribulose-1,5-bisphosphate), which is necessary to continue the cycle, a process that requires ATP.

RuBisCO

An enzyme that catalyzes the primary reaction of carbon fixation in the Calvin Cycle, combining carbon dioxide with RuBP (Ribulose-1,5-bisphosphate).