Chloroplast Vs Chlorophyll: Differences, Significance & Applications of Photosynthesis

In every discussion on photosynthesis, two terms you are likely to come across are chloroplasts and chlorophyll. Almost every biology beginner misplaced these two words, seeing that they always appear in similar contexts. To help solve this, I have put together this comparison of chloroplast vs chlorophyll.

Chloroplast and chlorophyll are two essential and different components in plant cells that are actively involved in the photosynthetic process. To start with, the chloroplast of a plant cell houses chlorophyll.

Beyond a comparison of chloroplast vs chlorophyll, the functions, significance, and relationship between chloroplast and chlorophyll are worth looking into. Understanding these gives insight into how they ensure harmony in the photosynthetic process.

What is chloroplast?

The chloroplast is a specialized organelle present in plant cells, algae, and some bacteria. They are tiny green structures, only visible to microscopes, with the responsibility of using energy captured from the sun to convert carbon dioxide (CO2) and water molecules into glucose (a form of chemical energy).

Each plant cell contains 20 to 100 chloroplasts, depending on the location of the cell. Each chloroplast is a network of stacked thylakoids, called grana, surrounded by a fluid-filled space called the stroma. The thylakoids are the main site of the photosynthetic process.

What is chlorophyll?

Chlorophyll, the green pigment of life, is a group of green pigments found in the chloroplasts. They are responsible for the green color of leaves. That is, yellow or red leaves lack chlorophyll, either due to a natural physiology or a deficiency.

On the electromagnetic spectrum, green is the only color the chlorophyll cannot absorb. It absorbs the red and green wavelengths and reflects the green wavelength.

Furthermore, they are synonymous with solar panels in the chloroplasts. These green pigments are components of the chloroplasts that draw light energy from the sun and convert CO2 and water molecules into chemical energy and oxygen.

Are there any similarities between chloroplast vs chlorophyll?

Chloroplasts and chlorophyll share a few similarities. They are:

  • They are both present in plants, algae, and certain bacteria cells
  • Both are essential to the photosynthetic process
  • Another similarity is “chloro-”, a term that means they are both green
  • Also, both components are involved in the light absorption process

Chloroplast vs chlorophyll: differences


Chloroplasts are membrane-bound organelles present in plant cells. They may be oval or spherical. They may also have plates-, cups-, or coil-like shapes in chlorella, Chlamydomonas, or spirogyra.

A chloroplast is usually about 4-5 micrometers in size and can number 20-100 in a cell, depending on the cell type.

The chloroplasts are surrounded by a double membrane envelope that has inner and outer layers, and an intermembrane space. This is one of the many similarities between the chloroplasts and the mitochondria.

The intermembrane space contains a fluid called the stroma. The outer layer is a permeable membrane, and the inner membrane encloses the internal compartment. In this internal compartment are tiny, flattened sacs called thylakoids. These sacs are stacked on each other to form the grana.

Unlike the chloroplasts, chlorophyll is a chemical compound. Its structure has a porphyrin ring, a phytol side chain, and a central magnesium atom.

There are four types of chlorophyll: chlorophyll a, chlorophyll b, xanthophyll, and carotene. All four have the same porphyrin ring and central atom but with a different side chain.

In addition, while chloroplasts have their DNA, chlorophyll does not. Since it is found in the chloroplasts, it also receives the genetic information in the DNA.


All species of plants contain chloroplasts, but not all plants have chlorophyll. This pigment is only present in green plants and autotrophs. Chlorophyll is the pigment responsible for capturing solar energy, which is converted into chemical energy in the chloroplasts.

In simpler words, the chloroplast is a house for chlorophyll, the more active component of the photosynthetic process. The chloroplast provides space and the necessary enzymes required for the light and dark stages of photosynthesis.

Furthermore, chlorophyll is the pigment behind the green color seen in chloroplasts, while the chloroplasts, in turn, impart this green color on the leaves of the plant.

Chloroplast vs chlorophyll: Significance in photosynthesis

The conversion of light energy to chemical energy

As chlorophyll molecules absorb light energy, they release high-energy electrons that drive several reactions in the chloroplasts. These electrons move through a series of protein complexes in the thylakoid membranes and form the electron transport chain.

Afterward, the electron transport chain forms a proton gradient across the thylakoid membrane, producing ATP, a form of energy.

Production of oxygen

After energy is captured by chlorophyll, the conversion of CO2 and water molecules into carbohydrates gives off oxygen as a by-product. This by-product goes into the atmosphere and is crucial to the respiration process of many living things.

Carbon fixation

The photosynthetic process involves the chloroplasts and chlorophyll in the process of carbon capturing and fixation. The chloroplasts provide the environment and necessary enzymes for this to happen. This process occurs in the Calvin cycle, which is the second stage of photosynthesis.

CO2 and O2 exchange

Through photosynthesis, the chloroplasts (with the help of chlorophyll) work to maintain a balance between CO2 and O2 molecules in the atmosphere. This is an essential process for the sustenance of life on the Earth.

Applications of photosynthesis

Production of biofuels

Photosynthesis is at the root of the production of biofuels like biodiesel and bioethanol. Plant biomass contains high amounts of energy from photosynthesis.

When converted to biofuels, it produces a cleaner and renewable alternative to fossil fuels, which produce hazardous air pollutants.

Carbon Capture and Storage (CCS)

Photosynthesis can also benefit carbon sequestration and climate change mitigation. Removing CO2 from the atmosphere reduces greenhouse gas emissions, reducing the effects of climate change.

Food source

The photosynthetic process is a source of food for the food chain. Every food chain starts with autotrophs, which use photosynthesis to produce food. Indirectly, every organism on the food chain relies on photosynthesis for survival.

Production of pharmaceuticals

The photosynthetic process also produces various secondary metabolites that are used in the production of several pharmaceuticals. These metabolites are obtained from plants through any of the many methods of phytochemical extraction.

Some common methods are solvent extraction, percolation, infusion, maceration, digestion, decoction, ultrasound-assisted, and microwave-assisted extraction.

Environmental remediation

As green plants carry out photosynthesis, they help to remove contaminants from the soil and water. As a result, they provide cleaner environments and better air.


What is the difference in the structure and color of chlorophyll a and chlorophyll b?

The chlorophyll molecule is a porphyrin structure with an isocyclic ring and a magnesium atom in the center.

The difference in structure of the two types of chlorophyll is their different functional groups. Chlorophyll A has a methyl group attached to its carbon 3, while chlorophyll B has a formyl or aldehyde group on its carbon 3.

Looking at them through a chromatogram – chlorophyll A is a blue-green pigment and chlorophyll B is yellow-green.

Are there factors that can affect the function of the chloroplasts?

The color and intensity of light affect the behavior of chloroplasts. The wavelength and intensity of light absorbed by the chlorophyll in the chloroplasts determine how much CO2 and water are converted into glucose molecules.

Does chlorophyll and chloroplast affect overall plant health?

Yes, they do. The more chlorophyll in a plant, the more sugar it can produce. The sugars are used to grow and store reserves in seeds, tubers, and bulbs. An unhealthy plant will not grow healthy and sufficient seeds or bulbs for food and replanting.

Similarly, the chloroplasts are responsible for producing energy through photosynthesis, which is necessary for the sustenance of plant growth and crop yield.

They are also the site of synthesis of active compounds and secondary metabolites which are vital to overall plant growth and yield.


The chloroplast is an organelle in the plant cell, and chlorophyll is the green pigment that absorbs light energy from the sun and uses it to convert carbon dioxide and water to glucose. This process occurs in the over a million chloroplasts present in a plant.

The chloroplast is not the same as chlorophyll, and vice versa. The differences, similarities, significance, and relationship between these two key players in the photosynthetic process point to the essence of this process in the sustenance of all living organisms.  

You can also learn about the process, benefits, and drawbacks of carbon fixation.

Thanks for reading.