Week 8 Johnson Lecture 1 Flashcards
How does the respiratory electron transport chain work?
Complex 1 uses NADPH and complex 2 uses succinate (derived from krebs cycle) to reduce ubiquinone to ubiquinol. Complex 3 oxidases ubiquinol back to ubiquinone. The electrons are passed on to cytochrome c. Cytochrome c recuses complex 4. Complex 4 reduces O2 to water. The free energy is used to pump protons to the intermembrane space
What is the trend seen in the electron transport chain of mitochondria?
THE ELECTRON TRANSPORT CHAIN IS A DOWNHILL (energetically favourable) flow of electrons, from a negative to a positive redox potential, via a series of sequential redox reaction, in each reaction the donor is oxidised and the acceptor is reduced
Where does photosynthesis take place in eukaryotes?
Chloroplast
What is the basic leaf structure?
Epidermal cells
a) Then palisade cells
b) Then the spongy mesophyll
c) Epidermal cells
What is the basic structure of a chloroplast?
Has 2 membranes
a) the chloroplasts plasm is called the stroma
b) Contains many stacked grana linked by the thylakoid membrane
What is the thylakoid membrane?
and what is the function of the thylakoid membrane?
The thylakoid membrane is highly folded, allowing 400 cm2 of membrane to be squeezed into 1 cm2 of leaf area, providing a huge area for light absorption and electron transport.
What happens in the thylakoid membrane?
It is where the photosynthetic electron transport happens.
What happens in the stroma?
CO2 fixation
How is photosynthesis split?
Light reaction and dark reaction
What happens in the light reactions of photosynthesis?
Two light-driven reactions in the chlorophyll-protein; complexes PSII and PSI result in electron transfer via a chain of acceptors from water to NADP+ with oxygen formed as a by-product. The electron transfer is, coupled to formation of a proton gradient for ATP synthesis
What is the redox ‘Z-scheme’ in photosynthesis?
Light energy is used by the reaction centres to drive energetically unfavourable reactions (+ΔG) that transfer an electron from a donor with a positive redox potential (water) to an acceptor with a more negative redox potential (NADP+) i.e. ‘uphill’. If both complexes’s reaction were plotted on a redox potential graph, it will look like a Z.
