The key difference between chlorophyll A and B is that the chlorophyll A is the primary photosynthetic pigment in plants and algae while the chlorophyll B is an accessory pigment that collects energy and passes to chlorophyll A.
Chlorophyll is a family of natural pigments that are present in plants and algae and is responsible for their green colour. Chlorophyll absorbs energy from sunlight and makes use of this energy to synthesize carbohydrates from water and carbon dioxide. It is the process called photosynthesis that sustains life processes in all plants as their energy requirements are met through this process. Furthermore, photosynthesis is the prime process that sustains all living organisms since plants are the primary producers of all food chains. Animals and humans consume products of plants. In the chlorophyll pigment family, there are several types of chlorophyll pigments. Among them, chlorophyll A and chlorophyll B are two types of chlorophylls. They have a similar structure with a slight difference in the porphyrin ring. Chlorophyll A has CH3 groups in the porphyrin ring while chlorophyll B has a CHO (aldehyde group) in the porphyrin ring.
CONTENTS
1. Overview and Key Difference
2. What is Chlorophyll A
3. What is Chlorophyll B
4. Similarities Between Chlorophyll A and B
5. Side by Side Comparison – Chlorophyll A vs B in Tabular Form
6. Summary
What is Chlorophyll A?
Chlorophyll A is the primary photosynthetic pigment present in plants and algae. It is the most widely distributing type of chlorophylls. It is a greenish colour pigment, which is able to capture energy from sunlight and produce foods in photoautotrophs. There are two types of photosystems that involve with the light reaction.
Figure 01: Chlorophyll A
In both photosystems, reaction centre consists of chlorophyll A molecules. They absorb red, blue and violet wavelengths and reflects green colour out. When considering the structure, it has a porphyrin ring similar to chlorophyll B. Yet, the porphyrin ring of chlorophyll A has CH3 side groups.
What is Chlorophyll B?
Chlorophyll B is an accessory photosynthetic pigment present in plants and green algae. It assists chlorophyll A by collecting energy and passing to it. Similar to chlorophyll A, it is a green colour pigment. Furthermore, it has a similar structure to that of the chlorophyll A.
Figure 02: Chlorophyll B
However, its porphyrin ring contains one CHO group, which is not present in chlorophyll A. These pigment molecules act as a light-harvesting antenna of photosystem I. Compared to chlorophyll A, chlorophyll B is less abundant. Furthermore, chlorophyll B is more soluble in polar solvents than the chlorophyll A. It primarily absorbs blue light.
What are the Similarities Between Chlorophyll A and B?
- Chlorophyll A and B are two types of chlorophylls which are green colour pigments.
- Both involve in photosynthesis.
- Also, both are able to absorb energy from sunlight.
- Furthermore, both are present in photosynthetic organisms, especially in green plants and algae.
- Besides, both their structures consist of a porphyrin ring.
- And, both of them are photoreceptors in the sense that they can make use of sunlight to make food for plants.
What is the Difference Between Chlorophyll A and B?
Chlorophyll A is the most abundant universal type of greenish colour chlorophyll pigment present in plants, algae and cyanobacteria. Thus, it is the primary photosynthetic pigment which absorbs light from red, blue and violet wavelengths and reflects green. Likewise, chlorophyll A is present within the reaction centres of both photosystems. On the other hand, chlorophyll B is an accessory pigment which collects energy and hand over to chlorophyll A. Therefore, this is the key difference between chlorophyll A and B.
Also, there is a difference between chlorophyll A and B in their structure. Chlorophyll A contains CH3 side groups attached to porphyrin ring while chlorophyll B has a CHO group attached to the porphyrin ring. More description about the difference between chlorophyll A and B is given in the below infographic.
Summary – Chlorophyll A vs B
In brief, Chlorophyll A and B are two types of green colour pigments of chlorophyll family. Chlorophyll A is the primary photosynthetic pigment while the chlorophyll B is an accessory pigment. On the other hand, Chlorophyll B collects energy and passes to chlorophyll A for exciting. Thus, this is the key difference between chlorophyll A and B. Furthermore, they have a small difference in their structures such as chlorophyll B has an aldehyde group attached to porphyrin ring unlike in chlorophyll A.
Reference:
1.Paul, Moumita. “Algal Pigments Structure and Function (2).” LinkedIn SlideShare, 30 Nov. 2016. Available here
2.“Chlorophyll b.” Wikipedia, Wikimedia Foundation, 11 Oct. 2018. Available here
Image Courtesy:
1.”Chlorophyll a structure”By Yikrazuul – Own work, (Public Domain) via Commons Wikimedia
2.”Chlorophyll b structure”By Yikrazuul – Own work, (Public Domain) via Commons Wikimedia