05.E BIO, C1 Light Dependent Reactions (PART E)

Light

Electromagnetic energy that is absorbed by chlorophyll and excites electrons found in the chlorophyll molecule

Electron Transport Chain (ETC)

A series of proteins found in the thylakoid membrane of chloroplasts that absorbs light energy to produced NADPH and ATP that is then used in the Calvin Cycle

Photosystems I & II

Consists of proteins that contain pigments found in the thylakoid membrane that capture and trap light energy

Chlorophyll

Pigment found within special proteins called photosystems that traps light energy

Excited Electrons

Electrons that have absorbed light energy and give off energy as they travel along the electron transport chain to pump H+ ions into the thylakoids space

Mobile electron carriers

Proteins found within the electron transport chain that move or "shuttle" the "excited" electrons from one protein to another within the electron transport chain

Hydrogen Ion Pump

Carrier protein found in the ETC that pumps hydrogen ions (H+) from the stroma into the thylakoid space

ATP Synthase

A protein (enzyme) found in the electron transport chain that transports hydrogen ions into the stroma via facilitated diffusion and uses energy from the flow of H+ through the channel to join ADP and phosphate to produce ATP

Transport proteins in the ETC (Examples)

Examples include:
H+ Pump
ATP Synthase

Enzyme in the ETC (Example)

Example includes:
ATP Synthase

Water (H2O)

Reactant in the light reactions that with light energy splits to produce hydrogen ions (H+) and oxygen (O2)

Hydrogen Ions (H+)

Ions found both inside and outside the thylakoid that are present in greater concentrations in the thylakoid space than in the stroma

Oxygen

A bi-product produced during the light reactions that is produced when water is split to provide electrons to the electron transport chain

NADP+

A molecule found in the stroma that accepts electrons that leave the electron transport chain to produce NADPH

NADPH

A molecule that is produced by the light dependent reaction that carries electrons and is used in the Calvin Cycle

ADP and phosphate

Molecules found in the stroma that in the Light Dependent Reactions combine to form ATP

Photolysis

A process in which water absorbs light energy and splits to form hydrogen ions, electrons and oxygen; the electrons generated replenish excited electrons that travel along the ETC; hydrogen ions (H+) generated help to maintain the high concentration of H+ inside the thylakoid

2H2O → 4H+ + 4e- + O2

Light Dependent Reactions (Chemical Reactions)

2H2O → 4H+ + 4e- + O2
ADP + phosphate → ATP
NADP+ + 2 electrons + H+ → NADPH

Light Reactions (Summary)

The Electron Transport Chain found in the thylakoid membrane of the chloroplast absorbs light energy that is then used to excite electrons; energy released by electron as it travels along ETC is used to transport H+ from the stroma into the thylakoid against the concentration gradient; hydrogen ions then move back out through ATP synthase and generate ATP; at the end of the ETC the electrons join with NADP+ to produce NADPH

Light Dependent Reaction (Reactants)

H2O, NADP+, ADP and phosphate

Light Dependent Reaction (Products)

O2, NADPH, ATP and glucose

Light (Label ETC)

Photosystem II (Label ETC)

High Energy Electrons (Label ETC)

Mobile Electron Carriers (Label ETC)

Hydrogen Pump (Label ETC)

Photosystem I (Label ETC)

ATP Synthase (Label ETC)