Difference Between Chlorophyll A and Chlorophyll B

Difference Between Chlorophyll A and Chlorophyll B: Chlorophyll is the pigment that helps green plants and certain algae produce energy from the sun’s light energy, water, and carbon dioxide. During this process, oxygen is released as a by-product. This pigment chlorophyll imparts the greenish color of green plants and other photosynthetic organisms.

Difference Between Chlorophyll A and B

The difference between Chlorophyll A and Chlorophyll B is given below:

Characteristics	Chlorophyll A	Chlorophyll B
Definition	Primary photosynthetic pigment i.e. the reaction center.	Accessory photosynthetic pigment.
Absorption spectrum	Absorbs violet-blue and orange-red lights which range from 430 nm to 660 nm.	It also absorbs violet-blue and orange-red light which ranges from 450 nm to 650 nm.
Occurrence	Found in all green plants, algae, bacteria, cyanobacteria,  etc.	Found in only green plants, and algae.
Reflection	It produces a bluish-green color.	It produces a yellowish-green color.
Rate of absorption	Its rate of absorption of light is strong.	Its rate of absorption is weak.
Side group	In its porphyrin ring, it has a -CH3 side group.	It has a -CHO side group in its porphyrin ring.
Molecular weight	Its molecular weight is around 839.51 g/mol.	Its molecular weight is around 907.49 g/mol.
Chemical formula	Its chemical formula is C55H72O5N4Mg2+.	Its chemical formula is C55H70N4O6Mg2+.
Structural difference	It has a methyl group.	It has a formyl group.
Solubility in polar solvents	It has low solubility in polar solvents.	It has a high solubility in polar solvents.

Chlorophyll

It is one of the important classes of green-colour pigment as it helps plants to perform photosynthesis i.e. the process of conversion of inorganic chemical substances into organic biomolecules with the help of the sun’s light energy. During this process, the sun’s light energy is trapped in the biomolecule formed as chemical energy that is required by all living systems to survive by performing any living process. This pigment is located in the thylakoid of the chloroplast organelle found in the parenchyma cells of the greenish parts of the plant and is the site of light reactions of photosynthesis. This molecule has a central magnesium atom that is surrounded by nitrogen-containing rings and a long hydrocarbon chain attached to one of the rings. There are different kinds of chlorophyll pigments that are differentiated based on the wavelength of light they absorb.

Structure of Chlorophyll

Chlorophyll pigment has a tadpole-like configuration with a porphyrin head and phytol tail. It was first studied by Wilstatter, Stoll, and Fischer in 1912. The Porphyrin head comprises four pyrrole rings and one isocyclic cyclopentanone ring attached to the third pyrrole ring. These four pyrrole rings are held together by a magnesium atom held in between. The phytol chain is a 20-carbon-long hydrocarbon chain that is connected to the fourth pyrrole ring.

Types of Chlorophyll

There are mainly four types of chlorophyll found in green photosynthetic organisms like plants, cyanobacteria, certain algae, etc. which are chlorophyll a, b, c, and d (however two very rare chl. e and chl. f are also found).

1. Chlorophyll a: Mainly found in green plants and forms the majority of the photosynthetic complex. It absorbs violet-blue and orange-red wavelengths of light.
2. Chlorophyll b: Mainly found in green plants but constitutes only about one-fourth of the chlorophyll content. It also absorbs light around violet-blue and orange-red wavelengths.
3. Chlorophyll c: Mainly found in marine algae, diatoms, etc. It absorbs blue-green wavelengths of light.
4. Chlorophyll d: Mainly found in red algae and cyanobacteria. It absorbs some wavelength in the blue-green region and most in the far red area.

FAQs on Chlorophyll A and Chlorophyll B

Q1: Name pigments other than chlorophyll.

Answer:

Xanthophyll and carotenoids.

Q2: Which pigment is termed the “universal photosynthetic pigment”?

Answer:

Chlorophyll a.

Q3: The four pyrrole rings in the porphyrin head are linked by?

Answer:

Four pyrrole rings in the porphyrin head are linked by Methine bridges (-CH=).

Q4: Which form of chlorophyll is considered a biological indicator?

Answer:

Phytoplankton contains chlorophyll A pigment in them and the quality of a water ecosystem is determined by the number of phytoplankton present in them. So, chlorophyll is considered as a biological indicator.