Photosynthesis Flashcards
Two processes in the photosynthesis
Light dependent and carbon fixation cycle
Two types of photosynthetic organisms
Oxygenic that produces oxygen and anoxygenic that don’t produce oxygen
Products of light reaction
ATP and NADPH
Anoxygenic organism uses what other pathway than carbon fixation
Reductive tricarboxylic acid cycle and hydroxypropionate pathway
Three photosynthetic pigments
Chlorophyll, carotenoids, and phycobilin
Are chlorophyll lipid soluble?
Yes
Types of chlorophyll molecules?
Chla, b, c, and d
Chlorophyll made of?
Chlorin and porphyrin
Chlorin has?
Three pyrolle rings and one pyrolline ring. One cyclopentanone ring and an isoprene tail
Porphyrin has
Four pyrrole rings.
In chlorophyll magnesium is bound to how many nitrogen and by which bond?
Two nitrogen by covalent bonds
Carotenoids
Long chain hydrocarbon having different isoprene residue in every molecule
Carotenoids are subdivided into?
Carotene and xanthophyll
Which one has oxygen, carotene or xanthophyll
Xanthophyll
Role of carotenoids
Acts as a scavenger and quencher. Protects from oxidative damage. By taking electrons from excited chlorophyll molecules and dissipating into heat.
What is photo inhibition
When an excited molecule reacts with oxygen it forms a singlet oxygen that is a reactive oxygen species
Phycobilin structure
Noncyclic, linear tetrapyrrole. Structurally similar to bilirubins.
Three types of phycobilin are?
Phycoerythrobilin, phycocyanobilin and allophycocyanobilin
What protein does phycobilin produce
Phycobiliproteins
Name the phycobiliproteins
Phycoerythin and phycocyanins.
Who has phycobilin?
Brown algae and cyanobacteria
Green photosynthetic bacteria has what photosynthetic pigment?
Chlorosome and plasma membrane
Purple photosynthetic bacteria has what photosynthetic pigment?
Chromatophore of plasma membrane
Absorption spectra
Degree of absorption by a molecule at different wavelengths
Action spectra
Different wavelengths affecting photochemical reaction
Photosynthetic unit? Discovered by?
A group of chlorophyll molecules that helps in producing one oxygen molecule. Discovered by Emerson and Arnold
What did hill reaction tell
That O2 is obtained from oxidation of H2O not CO2
What is the Hill Reagent? Why did he use it?
Hill reagent is Dichlorophenolindolphenol (DCPIP). He used it as an electron acceptor.
Quantum yield
It is the number of oxygen made from one photon
Quantum requirement
It is the number of photons used to make one oxygen.
Two components of photosystem
Photochemical reaction centre and antenna molecules
Two types of centre in photochemical reaction centre
Fe-S centre and pheophytin-quinone centre.
Which bacteria does not have an antenna complex
Helicobacter
Electron path in PS2
From P680* electron moves to pheophytin to plastoquinone to plastoquinol to cytb6f to plastocyanin and then to P700
In PS2, the core antenna and peripheral antenna contains what?
Core antenna - CD47 and CD43
Peripheral antenna - LHC2
In PS1 the peripheral and core antenna has which protein?
LHC1
What is the main ion in the oxygen evolving complex
Mn2+
Electron transfer in PS1
From P700* to modified chlorophyll molecules to phylloquinone to Fe-S complex to FD to FNR and then converts to NADPH
One molecule of CO2 forms how many G3P?
2 G3P
How many electrons are needed to form one NADPH
2e
How is ATP formed during this e transfer
The energy that is released while transporting the electrons is used to transport protons in the lumen. Then these protons are transported out of the lumen which forms ATP.
3 photons = 1 ATP
What forms during cyclic e flow? Is it beneficial?
Cyclic electron flow forms only ATP. It is preferred over non cyclic
Function of protein kinase?
Disassociates the LHC2 from from PS2 to PS1 for the e transfer to PS1
How many photons and protons used in cyclic e flow
4 photons and 8 protons
