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What Is the Monomer of a Protein? (Everything You Must Know)

Connor Sellers
Published by Connor Sellers
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: February 17, 2022

Protein has a complex structure and is made up of so-called monomers. But what are those monomers? And why does it even matter?

Well, knowing the structure of a protein can help you better understand why it’s so crucial for your health and fitness goals.

I’ve spent hours researching the science behind proteins to help you out. Here’s what I discovered about its monomers, structure, and roles in the body.

Quick Summary

  • Amino acids are the monomers of proteins.
  • Multiple amino acid chains make up polymers, like proteins.
  • Complete proteins are proteins that contain all nine essential amino acids.
  • Proteins play a role in many bodily processes.

What Are The Monomers Of Proteins?

amino acids

Amino acids are the monomers of proteins — their building blocks [1].

Before we go any further, let’s explain what monomers are in more depth.

In general, a monomer is a small molecule that joins other molecules to form a polymer. So, a polymer’s function and structure will depend on its monomers.

In other words, proteins largely depend on the amino acids that comprise them.

In fact, amino acids differentiate proteins from all other biological molecules: lipids, carbohydrates, and nucleic acids [2].

When amino acids join together, they form an amino acid sequence which determines a protein’s shape, size, and function.

Amino acids are also the reason why one protein differs from another. Two different proteins contain different amino acids.

But what makes one amino acid different from another?

After all, every amino acid has the same fundamental structure and chemical formula. Any single amino acid consists of a central carbon atom bonded to these four groups [3]:

  • An amino group (–NH2)
  • A carboxyl group (–COOH)
  • A hydrogen atom
  • An R-group

The carboxyl group is acidic, so that’s where amino acids derive their name from (the amino group + the acidic group = an amino acid).

So, all amino acids will contain a carboxyl group, an amino group, and one hydrogen atom. The only thing that differentiates one amino acid from another is the R group.

The R group is a variable atom or a group of atoms that determines a protein’s chemical nature — whether it will be acidic, basic, polar, or nonpolar.

Complete Vs. Incomplete Proteins

different food protein sources

The number and the type of amino acids in proteins allow us to differentiate between [4]:

Complete proteins contain all nine essential amino acids. These are the amino acids your body can’t produce on its own. Poultry, eggs, fish, and chia seeds are just some examples of complete proteins.

On the flip side, incomplete proteins may contain some but not all essential amino acids. Incomplete proteins are present in plants, such as lentils, peas, and beans.

5 Important Roles Of Proteins In The Body

different protein food sources

Proteins carry out many major functions in living organisms. For example, some proteins act as antibodies, while others function as enzymes.

Here, we’ll list only the most essential functions of proteins. Keep in mind that the full list of their roles is significantly longer.

1. Proteins Provide Structure

Collagen, keratin, and elastin give cells and tissues stiffness and rigidity. In other words, these proteins keep your body together [5].

Collagen is a versatile protein in your skin, nails, hair, bones, tendons, and ligaments.

Keratin mainly makes up nails, hair, and skin.

Elastin can be found in various structures that need to return to their initial position after stretching, such as a uterus or lungs.

You may need more protein if you have issues in any of the above areas, such as poor bone health.

2. Proteins Help You Grow And Maintain Tissue

man working out

Your body uses protein to grow and maintain tissues [6]. And that’s a valuable piece of information if you’re trying to build muscles.

Since muscles are tissues, you can increase them with protein.

The problem is that your body is constantly breaking down protein. If it breaks down more than it creates, you’ll need to get more proteins through food or protein supplements.

Your body’s protein requirements may also increase during pregnancy or while recovering from an injury.

But keep in mind that proteins alone won’t lead to muscle growth [7]:

“Adding more protein but not more calories or exercise to your diet won't help you build more muscle mass, but it may put your other bodily systems under stress.” - Gail Butterfield, Ph.D., RD, director of Nutrition Studies at the Palo Alto Veterans' Administration Medical Center

So, don’t expect miracles from proteins. You’ll still need to exercise and watch your diet if you want visible results.

3. Proteins Transport Nutrients Throughout Your Body

Proteins carry substances, such as vitamins and minerals, throughout your bloodstream.

That way, they ensure that every cell gets enough nutrients to function.

Besides transport, some proteins also store certain substances. For example, ferritin stores iron [8].

4. Proteins Boost Your Immune System

woman giving thumbs up

Proteins also act as antibodies that help you fight infection. If a virus attacks your cells, your body will produce a type of protective protein called immunoglobulin [9].

The body couldn’t fend off virus attacks without it.

Over time, your cells become better at producing antibodies.

They produce them more quickly each time your body gets attacked by the same virus.

Thanks to that, you’ll be less prone to harsh side effects if you catch the same virus again.

5. Proteins Lead To Biochemical Reactions

Enzymes are proteins that stimulate chemical reactions [10]. They have a specific structure that helps them combine with other molecules inside and outside the cell.

Combining with other molecules allows enzymes to perform many functions in our body:

  • Digestion
  • Blood clotting
  • Muscle contraction
  • Energy production

Do You Really Need Proteins?

Yes, you need proteins, both for natural processes in your body and for reaching your fitness goals.

Besides proteins per se, you also need amino acids.

Your body can produce non-essential amino acids on its own. But essential amino acids need to be supplied to your body through food.

But switching to a high-protein diet may require more time than you have.

In that case, consider investing in a protein supplement. It’ll pay off big time.


References:

https://www.ebi.ac.uk/training/online/courses/biomacromolecular-structures/biomacromolecular-structures

  1. https://www2.victoriacollege.edu/dept/bio/CoonsWebPages/biochemistry/biochemistry_print.html
  2. https://bio.libretexts.org/Bookshelves/Biochemistry/Book%3A_Biochemistry_Free_For_All_(Ahern_Rajagopal_and_Tan)/02%3A_Structure_and_Function/202%3A_Structure__Function_-_Amino_Acids
  3. https://www.webmd.com/diet/difference-between-complete-and-incomplete-proteins
  4. https://www.healthline.com/nutrition/functions-of-protein#TOC_TITLE_HDR_5
  5. https://pubmed.ncbi.nlm.nih.gov/20048505/
  6. https://www.webmd.com/fitness-exercise/features/will-eating-more-protein-help-your-body-gain-muscle-faster#1
  7. http://www.chemistry.wustl.edu/~edudev/LabTutorials/Ferritin/Ferritin.html
  8. https://www.creativebiomart.net/researcharea-immunoglobulins-proteins_82.htm
  9. https://medlineplus.gov/genetics/understanding/howgeneswork/protein/

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