BIOL 201 Lecture Notes - Lecture 10: Photosystem Ii, Electrochemical Gradient, Quinone
Bacteria also have similar ATP synthesis machinery
•
Proton gradient generated by photons, process
occurs in thylakoid membrane
○
Opposite concentrations gradient where lumen is
more acidic
○
Plants do it a little differently
•
The proton-motive force is conserved in bacteria, mitochondria,
and chloroplasts
Thylakoids form stacks that are called "grana" (sing. = granum)
•
Photosynthesis takes places on the thylakoid membrane of chloroplasts
Electrons flow to quinone carrier that transports electron within lipid membrane
•
•
Plastocyanin is water-soluble, can travel through lumen (like cytochrome c)
Pumping of protons across thylakoid membrane and into thylakoid lumen
•
The architecture is reminiscent of mitochondria and the ETC
Ability of light to liberate electrons from orbitals of nuclei
•
Electrons in outer orbitals of metal atoms are ejected when light is
shone on the surface
•
Einstein proposed "quantum" theory of light which represents set
amount of energy, aka energy necessary to liberate electron
•
Millikan later related photon wavelength to its energy
•
Photosynthesis takes advantage of the photoelectric effect
Electron normally exists in ground state (lowest energy)
•
Striking of electron by photon causes it to acquire energy
and enter and excited state
•
Non-radiative transitions between vibration states to
lowest possible excited state
○
Slightly higher states = vibration states
•
This is the basis of all fluorescence
○
Ex. Electron of GFP absorbs blue light and decays to
ground state, release green photons
○
Emission process has less energy that absorption due
to loss from non-radiative transitions
○
Needs to transition to different location or fall from excited
state back to ground state, and emit a photon that it
absorbed (fluorescence)
•
Absorption of a photon can push an electron into an excited state
Lecture 10: Photosynthesis and Section 1 Review
February 2, 2018
9:40 AM
Section 1 Page 1
Document Summary
The proton-motive force is conserved in bacteria, mitochondria, and chloroplasts. Proton gradient generated by photons, process occurs in thylakoid membrane. Opposite concentrations gradient where lumen is more acidic. Photosynthesis takes places on the thylakoid membrane of chloroplasts. Thylakoids form stacks that are called grana (sing. The architecture is reminiscent of mitochondria and the etc. Electrons flow to quinone carrier that transports electron within lipid membrane: plastocyanin is water-soluble, can travel through lumen (like cytochrome c) Pumping of protons across thylakoid membrane and into thylakoid lumen. Ability of light to liberate electrons from orbitals of nuclei. Electrons in outer orbitals of metal atoms are ejected when light is shone on the surface. Einstein proposed quantum theory of light which represents set amount of energy, aka energy necessary to liberate electron. Millikan later related photon wavelength to its energy. Absorption of a photon can push an electron into an excited state. Electron normally exists in ground state (lowest energy)
