Cells: How Does Cellular Respiration Work?

Cellular respiration. No, not breathing. Well, yes, breathing. We have the ability to breathe because we have the ability to create energy for our cells (called ATP) from glucose. This is done through two organelles in cells: the mitochondria and the chloroplast. Whether you’re a prokaryote or a eukaryote, and whether you’re a plant or an animal, determines which organelle you use to create energy. For the purpose of the exercise, let’s assume all of Sciencious’ readers are Homo sapiens.

Yes, that burger you had for lunch yesterday contained some sweet, sweet glucose that is helping you breathe, scroll, type and read on your device right now.

How does glucose get converted into ATP for the cells to use?

The glucose, along with oxygen, makes its way through the semi-permeable membrane. After entering the mitochondria, or chloroplast, ATP is produced, with waste products such as Carbon Dioxide, which you breathe out, water, and usable energy. The usable energy is then circulated through your body to your muscles to make everything work.
But let’s dig deeper. What actually happens behind the scenes and within the mitochondria and chloroplast itself?

There are three stages of cellular respiration with the mitochondria. Glycolysis, the Citric Acid Cycle, and the Electron Transport Chain (ETC). During Glycolysis, glucose and oxygen are the substrates that result in two ATP being made as products; the Citric Acid Cycle produces two more ATP. However, the ETC stage of cellular respiration results in 34 ATP being created to be used as energy. This results in an overall yield of between 36 and 38 ATP being produced through cellular respiration with the mitochondria.

In chloroplasts, cellular respiration occurs in two predominant stages: light dependent and light independent. Its glucose intake comes from the sun in a process called photosynthesis. Glycolysis still occurs in the chloroplast, similar to the mitochondria, however the inputs and outputs differ. While the mitochondria requires oxygen as an input, the chloroplast requires carbon dioxide as an input. During the light dependent stage, carbon dioxide is a waste product of cellular respiration, similar to in the mitochondria. However, during the light independent stage, the carbon dioxide input greatly increases, causing the intake of carbon dioxide to be greater the output of carbon dioxide.

The process of cellular respiration can be simply defined as the conversion of glucose into ATP for the cell’s usage. So, yeah, that is how you are breathing, scrolling, typing, and reading right now as you dust off the last of this article.

Featured image retrieved from:

Zac Cullen

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