Light Reactions-Photosynthesis
What is the waste product given off in the light reactions?
oxygen
What wavelength of light does PSII absorb?
680 nm
Which of the two wavelengths absorbed has more energy?
680 nm
What wavelength of light does PSI absorb?
700 nm
What are the two end products of the light reactions?
ATP and NADPH
What is meant by chemiosmosis? What does it produce?
ATP is formed from a build of of H+ ions inside a membrane; ATPs
Phosphorylation
Adding a phosphate to ADP to create ATP
What happens to the pH on the inside of the thylakoid when photosynthesis begins?
Becomes more acidic
Why is the flow of electrons from water to NADPH described as noncyclic?
Electrons do not end up in the same place that they started
What provides the energy to make ATPs in the light reactions?
Hydrogen gradient builds up, hydrogen goes through ATP synthase from inside to outside
What is the energy source for the light reactions?
Light
What color range are the two wavelengths in?
Red
Where do the electrons in PSII go?
Replace electrons in PSI
Where do they electrons from splitting water go?
Replace electrons in PSII
Where does the oxygen given off in photosynthesis come from?
Splitting water
Why is a membrane necessary to carry out the light reactions?
The membrane holds the molecules of the reaction in the right sequence
How do the electrons from P680 lose their extra energy so they can fit into P700?
They lose energy as they are passed to each carrier, eventually losing enough to fit into PSI
What is cyclic flow of electrons?
They start in the same place that they end
Why is cyclic flow necessary?
To balance the amount of NADPH and ATP
What is the function of the light reactions?
Turn light energy into ATP
What is the energy absorbed used to do?
Turn light energy into ATP and NADPH. Then, they are used in the dark reactions to make glucose.
Ferrodoxin
compound attached to the membrane which accepts electrons from PSI
Electron Carriers
compounds which pass electrons from one location to another in the thylakoid membrane
NADP Reductase
enzyme which attaches electrons and a hydrogen ion to NADP+
ATP Synthase
enzyme which makes ATP
Enzyme Z
enzyme which splits water
Where do the electrons in PSI go?
ferrodoxin
Photosystem
groups of chlorophyll and other molecules which absorb light of a certain wavelength
B6F Complex
large channel protein that moves hydrogen ions to the inside of the membrane
In what part of the chloroplast do the light reactions take place?
thylakoid membrane
photophosphorylation
using the energy of light to produce ATP
