Photosynthesis is the main and crucial source of food on the earth. Without photosynthesis, the carbon cycle would not occur, oxygen would not be produced and plants would not survive. Plants undergo photosynthesis with the interdependent support of two crucial elements called chlorophyll and chloroplasts. Though sound similar, yet have contrasting differences.
Chlorophyll vs Chloroplasts
The main difference between chlorophyll and chloroplast is that chlorophyll is a green pigment that is responsible for photosynthesis while chloroplasts is an organelle called plastid which has an abundance of the pigment chlorophyll. Chlorophyll is present in algae, green plants, and cyanobacteria while chloroplasts are present in all green plants and algae.
Chlorophyll is the absorber of light energy and the absence of chlorophyll can lead to chlorosis. Apart from the green pigment, chlorophyll can also contain carotenoids that are red and yellow pigments. Chlorophyll can be divided into two main types – chlorophyll A which is the principal pigment and chlorophyll B acts as the accessory pigment.
While chloroplasts act as a site for photosynthesis. The chloroplast structure has three membranes. The light energy received through chlorophyll is stored in two forms of energy-storing molecules – ATP ( Adenosine Triphosphate) and NADPH (Nicotinamide adenine dinucleotide phosphate).
Comparison Table Between Chlorophyll and Chloroplasts
| Parameters of comparison | Chlorophyll | Chloroplasts |
| Definition | The green pigment found in various algae, cyanobacteria, and plants is called chlorophyll | The organelles known as plastids that contain a high concentration of chlorophyll is called chloroplast |
| Word derivation | Derived from two Greek words “khloros” and “phyllon” | Derived from two Greek words “chloros” and “plastes” |
| Discoverer | Joseph Bienaimé Caventou and Pierre Joseph Pelletier | Hugo von Mohl discovered and Eduard Strasburger gave the name |
| Location | Around photosystems and embedded inside the thylakoid membranes of the chloroplast | Mainly in parenchyma plant cells. Also in some stem and collenchyma cells |
| Function | To absorb light energy and transfer it to the photosystem parts. It also produces electron flow in the reaction center. | To conduct photosynthesis, fatty acid synthesis, amino acid synthesis, and various immune responses and pathogen defense of plants |
What is Chlorophyll?
Chlorophyll is the green pigment found in plants, algae, and cyanobacteria. The word chlorophyll is derived from two Greek words “khloros” and “phyllon” which means pale green and leaf. It was discovered by Caventou and Pelletier in 1817 and the general structure was published by Hans Fischer in 1940. It is located in the mesosomes of cyanobacteria and the thylakoid membrane of chloroplasts of various plants and algae.
The job of chlorophyll is to impart green color to plants and algae and help plants in photosynthesis as the green pigment allows absorption of energy from light. The pigment appears green because the red and blue wavelengths are absorbed while the green is reflected.
Chlorophyll can be classified into two main types – Chlorophyll A and Chlorophyll B. Chlorophyll are also referred to as chlorins. The structure of a chlorophyll molecule consists of a fifth ring which is beyond the four pyrrole-like ring structures. It has a central magnesium atom.
Chlorophyll is synthesized by a branched pathway called the biosynthetic pathway. The vital enzyme involved is Chlorophyll synthase. The chlorophyll concentration within a leaf can be measured by a process called Ratio Fluorescence Emission. The insufficient production of chlorophyll leads to yellow patches on the leaf and is called chlorosis.
What is Chloroplast?
Chloroplasts are organelles that contain a photosynthetic pigment called chlorophyll and establish the photosynthesis process. The word chloroplast is derived from two Greek words “chloros” and “plastes” which imply green and the one who forms. It was discovered by Hugo von Mohl in 1837 and later Eduard Strasburger named the structures chloroplasts in 1884.
The job of chloroplasts is to conduct photosynthesis, fatty acid synthesis, amino acid synthesis, and various immune responses and pathogen defense of plants. The immune responses are carried out in two ways by the chloroplasts – hypersensitive response and systemic acquired resistance. Chloroplasts can also serve as cellular sensors.
Chloroplasts are found in the parenchyma cells and also in some collenchyma cells. In some plants like cacti, it is found in the stems. Chloroplasts can orient themselves according to the light, color, and intensity conditions prevailing. It is influenced by phototropin and blue-light photoreceptors. Chloroplasts are formed from secondary endosymbiosis.
Chloroplasts can be of various shapes depending upon the type of plant. It could be a lens, cup, net, ribbon, spiral, or star-shaped. Chloroplasts have three membranes – the outer chloroplast membrane, the inner chloroplast membrane, and the thylakoid system. It stores the light energy in the form of ATP and NADPH to run the internal processes.
Main Differences Between Chlorophyll and Chloroplasts
- Chlorophyll refers to the green pigment while chloroplasts refer to the organelles that contain chlorophyll within a plant cell.
- Chlorophyll is synthesized by a biosynthetic pathway while chloroplasts are considered to be evolved from endosymbiotic cyanobacteria.
- The structure of a chlorophyll molecule consists of a fifth ring which is beyond the four pyrrole-like ring structures while the structure of chloroplasts could be lens, cup, net, ribbon, spiral, or star-shaped.
- Chlorophyll has a vital role in photosynthesis as it captures light energy while chloroplasts store the light energy in the form of ATP and NADPH to make carbon dioxide by the Calvin Cycle.
- Chlorophyll is used in the food and hotel industry to color food and beverages green while sequenced chloroplast genome is used in biotechnology to improve plant quality and resistance.
Conclusion
Chlorophyll and chloroplasts play a vital role in plants for photosynthesis. They have an interdepending relationship as the former is a pigment while the latter is an organelle that contains the pigment.
Chlorophyll was discovered in 1817 while chloroplasts were discovered in 1837. Both the words have been derived from Greek. With the absence of chlorophyll, the plant can survive and may develop chlorosis but the plant cannot survive in the absence of chloroplasts as it would not be able to perform photosynthesis.
References
- https://www.nature.com/articles/253536a0
- https://tohoku.repo.nii.ac.jp/?action=repository_action_common_download&item_id=65038&item_no=1&attribute_id=18&file_no=1