Key Roles of Chlorophyll in Plant Biology Explained
Pigments which are responsible for the green colour in plants are chlorophyll pigments. Chlorophyll is one that among the major groups of the pigment, which are responsible for the conversion of sunlight into chemical energy and all this process occurs in the photosynthesis process. As the main function of chlorophyll is the absorption of sunlight, this energy is helpful in the conversion of carbon dioxide into carbohydrates. During all this process, oxygen is released as a by-product of photosynthesis. Along with plants, chlorophyll is also present in some organisms like Cyanobacteria.
Chlorophyll is further divided into various forms like chlorophyll a, chlorophyll b, chlorophyll c, etc but among them, chlorophyll a and chlorophyll b are mainly present in higher plants and green algae. Whereas chlorophyll c is found in marine algae and chlorophyll d is found in some of the species of cyanobacteria. Chlorophyll e is very rare as it is hardly found in few algae, like golden algae. Apart from all these things, chlorophyll structure is almost similar to structure of haemoglobin.
Location of Chlorophyll in Chloroplast:
Pigments of chlorophyll are mainly a green colour and they are light-dependent reactions. They absorb light from the sun i.e. red and blue light and convert this light into chemical energy which is their most important role in photosynthesis. In chloroplast, there is a structure termed as grana, which is made up of stacks of flattened discs called thylakoids and these thylakoids contain the photosystem and in these photosystems, photosynthetic pigments are present.
Role of Chlorophyll in Photosynthetic Process:
The major role of chlorophyll is in photosynthesis, as during this process plants absorb light energy and this light energy is converted into chemical energy. Using sunlight, carbohydrate synthesis takes place with the help of carbon dioxide and water. We can see the presence of chlorophyll in almost all green plants and some organisms like: green plants, cyanobacteria, and algae. In the photosynthesis process, chlorophyll absorbs sunlight of different wavelengths and with the help of carbon dioxide and water, they perform the synthesis process of carbohydrates. In chlorophyll, a magnesium ion is present in abundant amounts and this forms a large ring-like structure known as chlorine. A characteristic feature of chlorine rings is that they are heterocyclic compounds derived from pyrrole.
Important Features of Chlorophyll:
Some of the features of chlorophyll are discussed below:
A. Chlorophyll are known to be fat-soluble organic molecules having tetrapyrrole ring and due to this reason they are called the “Tetrapyrrole pigments or Magnesium chlorine”.
B. They are known to be food producers of the cell found in green plants, and they are mainly located in the chloroplast
C. Chlorophyll works as a factor for the proper growth of healthy and green plants.
D. Chlorophyll is also present in the mesophyll cells in the leaves of green plants.
E. Chlorophyll has a tendency to reflect green colour by absorbing red and blue wavelengths of light from sun rays.
F. It is also known as power of the cell-like mitochondria, as they help in the production of ATP.
G. Chlorophyll structure is similar to that of heme group of haemoglobin and cytochromes, which is derived from protoporphyrin
Difference Between Chlorophyll a and Chlorophyll b:
Difference Between Chlorophyll and Chloroplast:
FAQs on Chlorophyll Definition: What It Is and Why It’s Vital
1. What is chlorophyll and why is it important for life on Earth?
Chlorophyll is the green pigment found within the chloroplasts of plants, algae, and cyanobacteria. Its primary importance lies in its crucial role in photosynthesis. It absorbs light energy, primarily from the blue and red parts of the spectrum, and converts it into chemical energy. This process creates glucose (food for the plant) and releases oxygen, which is essential for most living organisms, including humans.
2. What is the main function of chlorophyll during photosynthesis?
During photosynthesis, the main function of chlorophyll is to act as a photoreceptor. It captures photons (light energy) and transfers this energy to reaction centres within the photosystems. This initiates the light-dependent reactions, leading to the synthesis of energy-carrying molecules like ATP and NADPH, which then power the creation of sugars in the light-independent reactions (Calvin cycle).
3. How can you explain the difference between chlorophyll and chloroplasts?
Chlorophyll and chloroplasts are related but distinct. A simple way to understand the difference is through an analogy: a chloroplast is like a factory, and chlorophyll is the machinery inside it.
- Chloroplast: This is the organelle (a part of the plant cell) where photosynthesis takes place. It is the entire 'factory'.
- Chlorophyll: This is the pigment molecule located inside the chloroplasts (specifically in the thylakoid membranes). It is the 'machinery' that absorbs sunlight.
4. What are the different types of chlorophyll and what do they do?
There are several types of chlorophyll, but the two most common in plants are:
- Chlorophyll a: This is the primary photosynthetic pigment in all plants, algae, and cyanobacteria. It is essential for converting light energy into chemical energy.
- Chlorophyll b: This is an accessory pigment found in plants and green algae. It absorbs light at different wavelengths than chlorophyll a and passes the captured energy on to chlorophyll a, broadening the spectrum of light that can be used for photosynthesis.
5. Why do leaves of plants growing in the shade often appear darker green?
Leaves in shady environments appear darker green because the plant compensates for the low light intensity by producing a higher concentration of chlorophyll pigments. To maximize the capture of every available photon of light, these plants increase the density of both chlorophyll a and b. This increased pigment concentration results in a darker, richer green colour compared to leaves growing in bright, direct sunlight.
6. What is the basic chemical structure of a chlorophyll molecule?
The structure of a chlorophyll molecule consists of two main parts:
- A porphyrin ring head: This is a complex ring structure with a magnesium atom at its centre. This part of the molecule is responsible for absorbing light energy.
- A phytol tail: This is a long hydrocarbon tail that is lipid-soluble. It anchors the chlorophyll molecule within the thylakoid membrane of the chloroplast.
7. If chlorophyll is so important, why do leaves change colour and fall off in autumn?
This seasonal change is a survival strategy. During spring and summer, the vibrant green of chlorophyll masks other pigments in the leaf. As autumn approaches, with shorter days and colder temperatures, plants stop producing chlorophyll to conserve energy. The existing chlorophyll breaks down, unmasking the yellow (xanthophylls) and orange (carotenoids) pigments that were always present. This reveals the classic autumn colours before the plant sheds its leaves to minimise water loss during winter.
