Photosynthesis: The making of ATP Flashcards Preview

A2 Biology: Photosynthesis & Respiration > Photosynthesis: The making of ATP > Flashcards

Flashcards in Photosynthesis: The making of ATP Deck (17):

what happens when a chlorophyll molecule absorbs light energy?

it boosts the energy of a pair of electrons within the chlorophyll molecule, raising them to a higher energy level


what are the electrons said to be when they are raised to a higher energy level?

electrons are said to be in an 'excited state'


what is photoionisation?

the electrons become so energetic that they leave/boost out of the chlorophyll molecule and become ionised


what are the electrons that leave the chlorophyll molecule taken up by?

a molecule called an electron carrier


having lost a pair of electrons, what has happened to the chlorophyll molecule?

chlorophyll molecule has become oxidised


having gained electrons, what has happened to the electron carrier molecule in the transfer chain?

electron carrier has become reduced


as the electrons pass down the electron transfer chain, what reactions do they undergo?

a series of redox reactions


where is the electron transfer chain located?

in the membranes of the thylakoids


why do electrons lose energy at each stage of the transfer chain?

because each new carrier is at a slightly lower energy level than the previous one in the chain


what is some of the energy lost in the transfer chain used for?

to combine an inorganic phosphate (Pᵢ) with ADP to form ATP


what is the name given to the mechanism of ATP production?

the Chemiosmotic Theory


how are protons (H⁺) pumped from the stroma and into the thylakoid membrane?

via protein carriers called proton pumps


where does the energy for the movement of the protons (H⁺) come from?

from the electrons released when water molecules are split by light (photolysis of water)


what further increases the proton (H⁺) concentration inside the thylakoid space?

the photolysis of water also produces protons (H⁺)


what is the concentration gradient of protons across the thylakoid membrane?

across the thylakoid membrane there is a high concentration inside the thylakoid space and a low concentration in the stroma


although most of the thylakoid membrane is impermeable to protons (H⁺), what can they only go through to cross this membrane?

ATP synthase channel proteins


what catalyses the reaction between inorganic phosphate (Pᵢ) and ADP to form ATP?

the protons (H⁺) passing through the ATP synthase channels cause changes to the enzyme's structure, which catalyses this reaction