Suppose a photosystem holds 300 pigment molecules in all…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Suppose a photosystem holds pigment molecules in all. (a) How many of them are in the antenna, and how many are at the reaction centre? (b) What does the antenna do with the light it absorbs? (c) Which pigment is at the reaction centre?
Need a reminder? The key ideaShow
Photosystems: PS I and PS II, named in the order of discovery. Each has an antenna (the light harvesting complex, hundreds of pigment molecules bound to proteins) and one chlorophyll a reaction centre: P680 in PS II and P700 in PS I. Water is split at PS II in the lumen: . Grana have both photosystems. Stroma lamellae have PS I but no PS II and no NADP reductase. Photon energy in eV with in nm.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The counts. One molecule forms the reaction centre. The antenna holds the other molecules.
Step 2. The job of the antenna. It absorbs light of many wavelengths and passes the energy to the reaction centre.
Step 3. The pigment. The reaction centre is a single molecule of chlorophyll a.
Answer: (a) molecules in the antenna and molecule at the reaction centre; (b) it passes the energy to the reaction centre; (c) chlorophyll a.
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