why do plants need chloroplasts and mitochondria

Why Do Plants Need Chloroplasts and Mitochondria?

Photosynthesis is the process used by plants and some organisms to convert light energy into chemical energy. This process supply fuel for the entire organism’s functions. It has 2 major players – the chloroplasts and the mitochondria. The chloroplast is where the actual photosynthesis process occurs where sunlight is captured. It is used to combine carbon dioxide and water and to produce glucose and oxygen.

The chlorophyll in the chloroplast is the one responsible for giving the plants the green hue. The mitochondrion (plural form: mitochondria) is the one that processes the glucose and converts it to energy to be stored. This energy is then used by the plant to still process nutrients through cellular respiration. So our question is since the plants already have the chloroplasts to produce the much-needed energy,  why do plant cells need both chloroplasts and mitochondria? Why are the mitochondria still playing a vital role in the process of making energy?

Endosymbiotic theory of mitochondria and chloroplast

Ever heard of the endosymbiotic theory of mitochondria and chloroplast? You see, the chloroplast and mitochondrion are organelles that were once free-living cells. They were once prokaryotic cells that soon turn into eukaryotic cells. This is by joining or invading other cells either through phagocytosis or parasitism. And instead of killing or being digested by the host cells, the inner cell survived and thrived together with it. This is what we called the endosymbiotic theory, which states that some organelles who are not multi-celled organisms were once single-celled organisms who lived on their own.  

Well, it might sound so complicated but it’s simple if you understand it by looking at how tenants and landlords work. What’s happening is that the host cell is providing a place for the organelle to stay comfortable. While the organelle is paying rent by providing the host cell energy to use. This happened eons ago and has resulted in the evolution of the cells, making way for the theory to exist. 

This is why do plant cells need both chloroplasts and mitochondria. Apart, before, they could have survived but only for a short time as each one requires the other to produce the energy the plant needs to thrive. They can longer exist without the other. And now, they function as a single organism. While both the mitochondria and chloroplasts produce energy for the plants, they both have distinct functions that the other one can’t do. 

Why do plant cells need mitochondria? 

Since plants already have chloroplasts, why do plant cells need mitochondria?

As mentioned above, the mitochondrion is the one in charge of producing energy for the plants. Energy to perform their functions throughout the day and night. While the chloroplasts are where the process of photosynthesis occurs, the mitochondria are where the energy the cells need to do just that. Without it, cells would die due to the lack of supply of energy. 

The way the mitochondrion acts in plants is that it creates a steady supply of adenosine triphosphate (ATP). It is the cell’s main energy-carrying molecule. This is why mitochondria are called the powerhouse of plants. They take the glucose produced by the plants and convert them to energy through oxidative phosphorylation. This is done via a series of enzymes and proteins which are then combined with oxygen to produce ATP. This completes the process of cellular respiration. This allows the mitochondria to process raw materials. And turn them into usable energy for plants to use in their daily function, with or without the sun.

Without the mitochondria, the plant would not be able to survive on its own. The plant cells would gradually die on its own since it doesn’t have the steady supply of energy it needs to convert raw materials to the nutrients it needs to function, which is why do plant cells need both chloroplasts and mitochondria. 

What would happen if the mitochondria and chloroplasts went missing?

We’ve already touched on the need for it but what would happen if the mitochondria and chloroplasts went missing all of the sudden? What would happen to the plants everywhere? Would there be any plants left?

As discussed previously, that would spell catastrophe to all vegetation that relies on it. The same goes for the chloroplast. Without the chloroplasts, there would be no cells capturing the sunlight from the sun and no place to process the nutrients and convert them into glucose and oxygen. No oxygen means bad for us human beings.  

And without mitochondria, there would be no powerhouse for the cells to get the energy they need to function. No powerhouse means no energy. And no energy means certain death to the organism. No vegetation means no food for the herbivores. This will then affect the food chain and then the ecosystem as a whole, which includes us human beings. 

Luckily, they’re here to stay, for good. So we shouldn’t be worried about it. Though it might be scary to think about it, the reasons why do plant cells need both chloroplasts and mitochondria shows us that they are not going away anytime soon. Unless, in some way, a new breed or species of plants would grow without it but that’s in the far future of evolution. 


Though they function separately in the plant cells, the plant needs both the chloroplasts and the mitochondria to survive anything nature can throw at them. Without the other, the plant would gradually die on its own as the cells in it deteriorate because of the lack of energy and it will do it from the inside out. Though the plants can process sunlight and raw materials on their own through the chloroplasts, without the mitochondria, the plant won’t have enough energy to do the same at night. This is why do plant cells need both chloroplasts and mitochondria. The organism cannot simply survive with only either one present in its system. 

It’s the same with us human beings. Without the ability to process raw materials from our sustenance, we wouldn’t be able to convert them to usable energy to do our day-to-day activities, much less have the energy to wake up and get up in the morning. 

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