What is the main difference between chlorophyll A and B?


The major difference between Chlorophyll a and b is that Chlorophyll a is green in colour it is a primary pigment and has a methyl group attached to third carbon while chlorophyl B is yellow green in colour and is accessory pigment. it has a aldehyde group attached to third carbon atom.

chlorophyll A vs chlorophyll B

Chlorophyll is a green pigment. It is present in all photosynthetic organisms. It is insoluble in water but it is soluble in organic solvents like carbon tetra chloride (CCl4), alcohol etc.

  1. There is difference of only one functional group of porphyrin ring between chlorophyll a and chlorophyll b. Chlorophyll a has methyl group (CH3) and chlorophyll b has carbonyl group (CHO) in place of methyl group. The molecular formula of the chlorophyll a and b are:difference between chlorophyll A and B
  • Chlorophyll a: C55H72O5N4Mg
  • Chlorophyll b: C55H70O6N4Mg
  1. The two chlorophylls show slightly different absorption spectra. So, these chlorophylls have different colors. Some waves that are not absorbed by chlorophyll a are absorbed by the chlorophyll b and vice versa. The difference in structure of different pigments increases the range of wave length of the absorbed light. Chlorophyll a is blue- green and chlorophyll b is yellow-green.



3. Chlorophyll a is the most abundant and most important photosynthetic pigment. It takes part directly in the light reaction of the photosynthesis.

It converts solar energy in to chemical energy. It is present in all photosynthetic organisms but it is absent in the photosynthetic bacteria. Chlorophyll a has several forms. These forms differ slightly in their red absorbing peaks (limits).

For example, they may absorb wave length of red colour of 670, 680, 690, and 700 nm. Chlorophyll b is present with chlorophyll a in all green plants and green algae.

Chlorophyll AChlorophyll B
It is known as principal pigment because it collects sunlight for plants for photosynthesis.it is called an accessory pigment which also collects sunlight for plants but passes it to Chlorophyll A.
around 1-3 μm particle can be ingested.while in this case, 0.1 to 0.2 μm sized liquid droplets can be ingested.
light in the range of 430nm to 660 nm can be absorbed. light in the range of 450nm to 650 nm can be absorbed.
450 to 462 nm wavelengths can easily be absorbed in Chlorophyl A470 nm wavelengths can easily be absorbed in Chlorophyll B
they absorb orange-red and violet-blue lights from the spectrum of light. they can only absorb orange-red light from the spectrum of light.
they reflect the blue-green color.they reflect yellow-green color.
contains the methyl group in the chlorin ring in third position. contains the aldehyde group in the chlorin ring in the third position.
their molecular weight is 839.51 g/mol. their molecular weight is 907.59 g/mol.
all plants, algae, and cyanobacteria are sources. found in almost all plants and green algae only.
present as a total amount of 3/4 of total chlorophyll in plants. present as a total amount of 1/4 of total chlorophyll in plants.
in polar solvents, their solubility is low.high soluble in polar solvents.
they are present at the reaction center of the antenna array. they regulate the size of the antenna.

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