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 color it is a primary pigment and has a methyl group attached to the third carbon while chlorophyll B is yellow-green in color and is an accessory pigment. it has an aldehyde group attached to a third carbon atom.

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 a difference of only one functional group of porphyrin ring between chlorophyll a and chlorophyll b. Chlorophyll a has a methyl group (CH₃) and chlorophyll b has a carbonyl group (CHO) in place of the methyl group. The molecular formula of chlorophyll a and b is:

• Chlorophyll a: C₅₅H₇₂O₅N₄Mg
• Chlorophyll b: C₅₅H₇₀O₆N₄Mg

2. 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 chlorophyll b and vice versa. The difference in the structure of different pigments increases the range of wavelength 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 photosynthesis.

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

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

Chlorophyll A	Chlorophyll B
It is known as the 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 particles 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 Chlorophyll A	470 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 the 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 the 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.