Art1- ATP

ATP Energy Production

This article gives an overview of the cell, and cellular respiration. We’ll cover the central role of the mitochondria for adenosine triphosphate (ATP) energy production, and discuss the role light plays. We’re going under the microscope for a look at cellular function

What is a Cell?

Cells are the basic building blocks of all living things, including you. A cell is the smallest unit of life, and the human body is made up of trillions of them. They’re responsible for the processes that make life possible, like giving the body structure and allowing it to grow and heal, and holding the body’s hereditary material and producing proteins. 

The nucleus is the command center of the cell, and holds the body’s DNA. Crucially, cells also power the body by taking in nutrients and oxygen and converting them into usable energy. That unit of energy is called ATP energy. It’s created most efficiently in the cellular respiration process, and the mitochondria in the cell plays a major role. [1]


The Mitochondria in Cells Power the Body 

Mitochondria are double-membrane structures in our cells responsible for cell signaling, steroid synthesis, cell apoptosis, and cellular energy. [2] Mitochondria are often referred to as the “powerhouse of the cell” because they convert food, water, and oxygen into ATP energy the cells and body can use. ATP energy is crucial for your body’s function; it’s often called “the energy currency of life.”

Mitochondria are unique, with their own ribosomes and DNA. They’re typically round or oval in shape and microscopic, so we can’t physically see them, but they affect just about everything we do. There can be as few as 1-2 mitochondria per cell, or as many as thousands. This changes in response to physiological conditions such as exercise, nutrients, or with aging. [3]


What is Adenosine Triphosphate (ATP)?

ATP is a high-energy molecule whose sole function is to store energy in our cells. Our body uses it to do pretty much everything. Some cells (like muscle cells) require a lot more ATP than others because of the intense demands placed on them. In a constant effort to achieve homeostasis, or balance, humans recycle their own body weight equivalent in ATP every single day. [4] The more efficiently cells can make and use energy, the better the body should function. 


ATP Energy is Created Through Cellular Respiration

ATP is created using cellular respiration, one of the most efficient metabolic pathways on earth. This process involves using several key ingredients: the oxygen we breathe, the water we drink, and the food we eat.

The Role of Charge, Coenzymes, and Hydrogen: Before we get microscopic and explain cellular respiration, we need to quickly touch on a few concepts that are central to cellular respiration, like charge, coenzymes, and hydrogen.

  • Charge: Electrons (-) and protons (+) are the charges of life. Everything that exists in our universe operates using a negative and positive charge. When a compound sheds electrons, it’s called oxidation. When it gains electrons, it’s called reduction (because more electrons means more negative charge).
  • Coenzymes: These are the cargo trucks of cellular respiration, the small molecular compounds that transport protons and electrons into the mitochondria. Nicotinamide Adenine Dinucleotide (NAD+) & Flavin Adenine Dinucleotide (FAD) are the two crucial coenzyme carriers in cellular respiration.

  • Hydrogen: Hydrogen ions (H+) have a positive charge and play a key role in cellular respiration. When NAD+ or FAD pick up electrons, they also pick up H+ ions, which converts them into a reduced state, resulting in NADH or FADH2 (also types of coenzymes). Your key takeaway on hydrogen should be that it’s needed to complete the 4-stage process of cellular respiration; without it, we cannot make ATP.


4 Stages of Cellular Respiration


ATP can be created two ways: aerobic (with oxygen) or anaerobic (without oxygen). Aerobic is much more common and beneficial, because it produces more energy. [6] Aerobic cellular respiration has four stages. In the first two stages, our bodies strip nutrients from our food, turning them into usable fuel in the form of carbon compounds.


1. Glycolysis: The basic metabolic pathway in all organisms where food is broken down into chemical compounds called pyruvate. [5]

2. Pyruvate Oxidation: Pyruvate is broken down (oxidized) into Acetyl-CoA. When anything is oxidized, it means that it loses its electrons.


Those electrons are picked up by NAD+, which grabs a hydrogen ion and forms NADH. Carbon dioxide is generated as waste and we are off to stage 3. [6]

In steps 3 & 4, carbon compounds are converted into the vast majority of energy used by aerobic cells (over 95% of cell energy in humans is produced through this process).


3. Citric Acid Cycle: This is the metabolic core process of the cell. The main function of the citric acid cycle is oxidation, where high-energy electrons and protons are harvested from the carbon compound (acetyl-CoA) created during the previous stage. This creates electron and proton carriers (coenzymes) called NADH and FADH2. Electrons and protons have to be oxidized into these individual coenzyme units to create ATP during the final stage of cellular respiration. This is a highly efficient and important process because a limited number of molecules generate large amounts of NADH and FADH2. [7]


4. Oxidative Phosphorylation: The process starts when electron carriers NADH and FADH2 unload electrons slowly into the electron transport chain (ETC), which creates energy. As electrons flow down the ETC, they meet up with oxygen to form water and CO2 as byproducts. At the same time, hydrogen ions (H+) are released as NADH & FADH2 are oxidized. H+ ions are then pumped upstream through protein complexes I, III, & IV into the intermembrane, where they build up. As they begin to gather, potential energy is created in the form of a gradient. Those ions then flow downstream through an enzyme called ATP synthase, where they re-enter the matrix as ATP molecules. 

When cellular respiration is broken down to the atomic level, it becomes clear why it all boils down to electrons (e-) and protons (H+) for ATP production. [8]


How Does Red and NIR Light Enhance ATP Production?

Red light therapy is designed to enhance cellular function. It can help reduce inflammation, improve blood flow, and enhance the performance of energy-making mitochondria in the cell. 

Red light therapy can increase the number of mitochondria [9], and also boost their function in the cell. [10] One of the main mechanisms of red light therapy related to mitochondrial function is a higher-performing electron transport chain mediated by cytochrome C oxidase (Cox). In addition, there is the possible dissociation of binded nitric oxide (NO) and Cox (NO-Cox), which is a harmful roadblock to ATP production. [11] Essentially, NO-Cox gunks up the cellular system of ATP production, and red and NIR light helps prevent and reverse this problem. 

NO is a competitive inhibitor of oxygen, which means it takes oxygen’s rightful place on the ATP synthase enzyme and causes the cell to work less efficiently as a result. During the creation of ATP synthase, NO competes with oxygen, which limits the eventual production of ATP. This also increases oxidative stress, which can lead to cellular death. [12] The photons in red and NIR light excite electrons, which helps break up nitric oxide bonds so H+ ions can move through the process more effectively, resulting in greater levels of ATP energy that power your cells and body. [10].


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