Catabolism vs. Anabolism: What’s the Difference

What Is Catabolism?

Catabolism refers to the breakdown of muscle tissue into amino acids. The body uses these amino acids to build new proteins or make protein from other substances. There are two types of catabolic processes: 1) the breakdown of muscle tissue (muscle wasting), 2) the synthesis of new muscle tissue (anabolic). A person may have both types of processes going at once.

The breakdown of muscle tissue is called sarcopenia. Muscle wasting occurs when there is not enough energy in the muscles to support normal activity levels. Muscles become weaker and less efficient at performing their function. For instance, if someone were to walk up stairs with a heavy backpack, they would need more strength than before because the weight was too much for them to lift without breaking down some of their own muscle fibers.

If they continued walking up the stairs, they would eventually collapse due to exhaustion.

Muscle wasting is often associated with age, but it can occur at any time in most people. Some cases of sarcopenia are reversible through exercise training and nutrition. However, most cases will require medical treatment such as surgery or drugs to reverse the condition.

Anabolic steroids are used for many reasons including increasing muscle mass and improving athletic performance. They work by mimicking the effects of testosterone and dihydrotestosterone in the body.

What Is Anabolism?

The term anabolism refers to all the actions in the body that build up tissues and allow cells to grow and reproduce. In other words, it is the exact opposite of catabolism. Many of the functions of anabolism are regulated by hormones such as growth hormone, insulin, and testosterone.

There are several types of anabolic reactions, but they all share a few things in common. Most notably, they all require energy to complete. The building up of complex molecules requires a significant amount of energy because they need to be pulled apart and then reassembled one piece at a time. In other words, it is often very hard work for the body to perform these tasks.

The production of ATP is necessary for anabolic reactions to proceed. ATP (adenosine triphosphate) is the “energy currency” of cells, and most chemical reactions in the body require it in order to proceed. In fact, many of the reactions that produce ATP from ADP (adenosine diphosphate) are actually part of anabolism.

Anabolic reactions are most often concerned with building up the body’s tissues. For example, when the body breaks down protein from food, anabolic reactions reassemble the amino acids into new proteins that have many uses in the body. When carbohydrates are broken down and absorbed, anabolic reactions form new glycogen molecules for storage in the liver and muscle cells. Fatty acids are broken down into glycerol and fatty acid molecules that can be used to produce several other important substances.

In each case, the anabolic reactions are building up these substances into useable forms that the body can use.

Anabolic reactions occur most often in the cells of the liver, thyroid gland, and intestines. They also occur in muscle cells, bone cells, red blood cells, and other specialized cells. The second half of this article describes some of the most important anabolic reactions found in these various organs and tissues.

Protein Metabolism

Proteins are organic compounds made of amino acids, and they are the building blocks of cells and tissues in the body. To perform their function in the body, every protein is made up of a specific sequence of amino acids that allows it to interact with other molecules or to perform a certain function.

Proteins are continually being broken down in the body then reformed as needed. Proteins cannot be stored for later use, so they are broken down as needed by anabolic reactions and the constituent amino acids are then reused to create new proteins that are needed.

The process of breaking down proteins in the body is called proteolysis. The enzymes responsible for this task are very specific, so they will only break down certain proteins.

Sources & references used in this article:

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Searches for exploitable biochemical differences between normal and cancer cells. VII. Anabolism and catabolism of purines by minced tissues by GP Wheeler, JA Alexander – Cancer research, 1961 – AACR

Teaching the basics of cancer metabolism: Developing antitumor strategies by exploiting the differences between normal and cancer cell metabolism by B Kalyanaraman – Redox biology, 2017 – Elsevier

Quantitative laws in metabolism and growth by L Von Bertalanffy – The quarterly review of biology, 1957 – journals.uchicago.edu

Famine versus feast: understanding the metabolism of tumors in vivo by JR Mayers, MG Vander Heiden – Trends in biochemical sciences, 2015 – Elsevier

The influence of prolonged muscular rest on metabolism by DP Cuthbertson – Biochemical Journal, 1929 – portlandpress.com