Topic 5 - Energy Transfers in between organisms Flashcards
What is grana?
Stacks of thylakoid membranes which provide a large surface area for the attachment of chlorophyll, electrons and enzymes.
What is photoionisation?
The process by which photons of light hit chlorophyll molecules in PSII causing electrons to become excited.
What is photolysis?
The splitting of water with light.
One molecule of water requires 4 photons of light to split.
What happens when water is split?
One molecule of oxygen, 4 protons and 4 electrons are produced.
How are the one molecule of oxygen, 4 protons and 4 electrons used after their formation?
- The oxygen naturally diffuses out through the stomata or is used in respiration.
- The 4 electrons replace those lost from the chlorophyll.
The protons move into the stroma, creating a proton gradient.
Where do excited electrons move down?
They move down a series of protein complexes. At one complex, the energy from the electron is used to pump 4 protons from the stroma to the thylakoid space.
After moving down a series of protein complexes, where does the electron move?
It moves down the chain further to PSI. Here, more photons of light are absorbed causing the electron to move back up to a high energy level.
After the electron moves back up to a high energy level, what happens?
It moves along the chain to another complex where the electron combines with a proton to form a hydrogen atom. This is used to reduce NADP, forming reduced NADP.
What does the pumping of proteins across the membrane mean?
It means that there is a greater concentration of proteins in the thylakoid space than the stroma. This forms a protein gradient that is a high conc. in the thylakoid space and low in the stroma.
What does the movement of protons do?
The movement of proteins drives the process of phosphorylation.
What does the enzyme ATP synthase do?
It phosphorylates ATP from ADP and Pi.
What is carbon dioxide fixation in the light independent reaction?
CO2 that diffuses in through the stomata is fixed with RuBP in a process called carboxylation.
What is the rubisco enzyme needed for?
This enzyme is needed for the carboxylation process.
What is formed in the carboxylation process?
A 6 carbon sugar is formed first, however it is very unstable and therefore forms 2 molecules of glycerate-3-phosphate.
What is the reduction phase?
The 2 molecules of glycerate-3-phosphate contain a -COOH group and so are an acid. The reducing power of reduced NADP reduces the glycerate-3-phosphate with energy provided by ATP.
