Plants are living creatures that depend on themselves for food. The process that they use for creating their food is known as photosynthesis. This process requires a pigment called chlorophyll. The green color of the leaves is mainly because of the green pigments which it contains in the plant cell called the chlorophyll. The plant uses this green pigment to convert light energy into chemical energy through the process of photosynthesis.
The two most common types of chlorophyll found in plants are Chlorophyll A and B. Both of these play significant roles in the process of photosynthesis as they help to absorb sunlight that is needed for the production of carbohydrates. They are found in chloroplasts.
Chlorophyll A vs B
The main difference between chlorophyll A and chlorophyll B is regarding their part in photosynthesis. Chlorophyll A is the most important pigment used in the process of photosynthesis whereas chlorophyll B is the secondary pigment, as it collects the energy and passes it to chlorophyll A.
Comparison Table Between Chlorophyll A and B
| Parameters of Comparison | Chlorophyll A | Chlorophyll B |
|---|---|---|
| Definition | Chlorophyll A is the prime pigment used in photosynthesis. It captures sunlight. | Chlorophyll B is the additional pigment used in photosynthesis. It collects sunlight and passes it to chlorophyll A. |
| Range of absorption | 430 mm to 660 mm. | 450 mm to 650 mm. |
| Color of absorption | This absorbs orange-red and blue-violet light. | This absorbs orange-red light. |
| Reflecting color | Chlorophyll A reflects a blue-green color. | Chlorophyll B reflects a yellow-green color. |
| Absorbing wavelength | It absorbs wavelength 430 nm and 662 nm. | It absorbs wavelength 470 nm. |
| Structure | Chlorophyll A contains a methyl group. | Chlorophyll B contains an aldehyde group. |
| Molecular Weight | 839.51 g/mol | 907.49 g/mol. |
| Chemical Formula | C55H72MgN4O5 | C55H70MgN4O6 |
| Found in | It is found in algae, plants, and cyanobacteria. | It is found in algae and plants. |
| Quantity | ¾ of total chlorophyll. | ¼ of total chlorophyll. |
| Solubility in polar solvents | Low | High |
What is Chlorophyll A?
Chlorophyll A refers to the green pigment which helps in absorbing light and providing energy in the process of photosynthesis. It is present in algae, cyanobacteria, and all plants.
Chlorophyll A is regarded as the most essential pigment for plants as it plays an important role in photosynthesis. It helps in the electron transport chain during photosynthesis.
It is also responsible for transferring light energy from the antenna to the photosystems P680 and P700. Here chlorophylls are found in the thylakoid membrane of the chloroplast.
The wavelengths responsible for violet-blue and orange-red colors are 429 nm and 659 nm respectively.
It reflects bluegreen color, which brings out the green color in most plants.
Chlorophyll A has a chlorin ring. Here a magnesium ion is surrounded by four nitrogen atoms. It also consists of some side chains and hydrocarbon tails.
Hence, we can say that the basic role of Chlorophyll A is to absorb light from the orange-red and violet-blue colors of the spectrum and transfer this energy to the reaction center. It then provides two electrons to the electron transport chain. Basically, it is the most important electron transport donor. Further, the organisms use the energy from the sun for the cellular processes.
What is Chlorophyll B?
Chlorophyll B is a green pigment that helps in photosynthesis as it collects light energy and then passes it to chlorophyll A. It is present in plants and green algae.
The wavelengths responsible for violet and red colors are 455 nm and 642 nm respectively.
It reflects a yellow-green color. Chlorophyll B is present in light trapping antenna in photosystem P680 in most land plants. It has a similar structure to chlorophyll A, the only difference is that chlorophyll B has an aldehyde group in the C7 position of the chlorin ring.
Hence, we can say that the main role of Chlorophyll B is to increase the absorption spectrum of organisms. This helps them to absorb more energy and basically helps organisms to convert more energy from the sun into chemical energy.
Main Differences Between Chlorophyll A and B
- Chlorophyll A is the main pigment used in photosynthesis as it captures sunlight whereas Chlorophyll B is the extra pigment used in photosynthesis as it gathers sunlight and passes it to chlorophyll A.
- Chlorophyll A holds a methyl group in the third place of its chlorin ring whereas chlorophyll B holds an aldehyde group in the third place of its chlorin ring.
- Chlorophyll A absorbs energy in the range of 430 nm to 660 nm whereas Chlorophyll B absorbs energy in the range of 450 nm to 650 nm.
- Chlorophyll A is found in bacteria, algae, cyanobacteria, phototrophs, and all plants. On the other hand, Chlorophyll B is found in plants and algae.
- Violet-blue and orange-red energy are absorbed from the spectrum by Chlorophyll A whereas Chlorophyll B absorbs only orange-red energy from the spectrum.
- The reflecting color of chlorophyll A is a blue-green color. The reflecting color of chlorophyll B is a yellow-green color.
- 839.51 g/mol is the molecular weight of chlorophyll A. 907.49 g/mol is the molecular weight of chlorophyll B.
- C55H72MgN4O5 is the chemical formula of chlorophyll A. C55H70MgN4O6 is the chemical formula of chlorophyll B.
- ¾ of the total chlorophyll in plants constitute Chlorophyll A. ¼ of the total chlorophyll in plants constitute chlorophyll B.
- Chlorophyll A is there in the reaction center of the antenna array. Chlorophyll B controls the size of the antenna.
Conclusion
The main role of chlorophylls is to absorb light for the process of photosynthesis. The two primary types of chlorophyll are A and B. Both chlorophyll A and B are the two important pigments, used in photosynthesis.
Basically, the primary difference between chlorophyll A and B is their roles in photosynthesis.
The main job of chlorophyll A is that it is an electron donor in the electron transport chain whereas Chlorophyll B’s role is to help the organisms to absorb higher frequency blue light which is used for photosynthesis.
Chlorophyll A is present in all organisms that carry out photosynthesis, but not all organisms have chlorophyll B.
References
- https://www.sciencedirect.com/science/article/pii/S0034425798000467
- https://pubs.acs.org/doi/pdf/10.1021/ja00964a011