M
ost green land plants have two main
types of Chlorophyll - Chlorophyll A
and Chlorophyll B.
Chlorophyll A is
the primary active pigment (chemi-
cal) in photosynthesis.
Chlorophyll A
will reside in both PSII and PS I in the
diagram on the opposite page.
In PSII
there is another label P680 - this rep-
resents Chlorophyll A that accepts light
waves up to 680 nm. This is where the
production line begins and it’s where
electrons are passed from this stage to
the next.
Eventually we arrive at PSI
where you see a P700, which has Chlo-
rophyll A that best reacts to light waves
greater than 680 nm up to 700 nm.
In
fact you might see Chlorophyll A rep-
resented as Chlorophyll A 700, Chloro-
phyll A 660 or Chlorophyll A 680 etc. to
represent the different subcategories of
Chlorophyll A.
PSI is where NADPH is created, which
is one of the main energy stores, a tem-
porary battery you might say.
Chlorophyll B is called an accessory
pigment and resides mostly in PSII.
When light is low, a plant will produce
more Chlorophyll B, which can then
help the process by transferring even
more electron energy to be used further
on in the production line.
In effect, in
low light situations, having more Chlo-
rophyll B, with a slightly different range
of wavelength, means that together
with Chlorophyll A, a plant has a larger
range to collect light energy.
There are many other classifications of
Chlorophyll other than A and B;
There
is C1, C2, D, F and Carotenoids used by
other plants or even bacteria, or act as
accessory pigments (like B).
T
here are actually many more types of Chlorophyll
that are found in species other than garden variety
green plants - there is chlorophyll c1 (algae), Chlo-
rophyll c2 (algae), Chlorophyll d (Cyanobacteria,)
Chlorophyll f (Cyanobacteria).
Of particular inter-
est are the Chlorophylls for algae, which someday
might be used commercially as biofuels to replace
fossil fuels.
It was first proposed by Harder and
VonWitsch in 1942. Today, millions of dollars are
being spent on continuing research, with a few
companies already having commercially sold these
biofuels as early as 2012.
Photobioreactor - By IGV Biotech - Own work, CC BY-SA
3.0, h±ps://commons.wikimedia.org/w/index.php?cu
-
rid=25767679
Did you know?
BioFuels from Algae are commercially available.
Chlorophyll A resides in these two places (PSII
and PS1). Chlorophyll in PSII can receive light up
to 680nm in wavelength, while Chlorophyll in PSI
can receive light wavelength up to 700nm.
Chlorophyll B resides mostly in PSII (they also
reside in PSI in smaller numbers) and is produced
in more numbers when light is low, and since it’s
peak wavelengths are different from Chlorophyll
A, it gives the plant a larger range of light-wave-
length to receive light energy.
400
500
600
700
Chlorophyll F
Carotenoids
Chlorophyll B
Chlorophyll A
Light Wavelength (nm)
Light Absorp�on
Chlorophyll A & B
18
17
Grow Light PAR Meter