Protein Synthesis Analogy

Instructor: Bridgett Payseur

Bridgett has a PhD in microbiology and immunology and teaches college biology.

There are hundreds of thousands of types of proteins in living things, but they are all made using a similar process. This process is like building a house, with instructions to direct workers what to bring in and install the proper parts.


Proteins are the workhorse of the cell. They do everything that needs to be done. Proteins can:

  • act as enzymes, speeding up chemical reactions.
  • provide structure to the cell and the body, in the form of the cytoskeleton, hair, and fingernails.
  • move materials in and out of the cell and all around the body.
  • help make your muscles move.

In short, without proteins, nothing would be happening in your cells or in your body.

One way to understand how proteins are made is to consider a house being built. This lesson will go over the main players in protein synthesis, and how they work together to build the protein house.

DNA and mRNA

You might be wondering why, if proteins do everything for the cell, you always hear about DNA being the building block of life. The DNA in a cell contains the instructions for making proteins. If the DNA is changed, this can result in the proteins being changed too, which can sometimes have serious consequences.

DNA would be like the ideas in an architect's head as he or she begins to design a new house. These ideas need to be written down into a blueprint that can easily be transported to the work site. In a cell, this process of writing down instructions from DNA is called transcription. Transcription normally means to take spoken words and write them down. This makes sense, because the DNA instructions are being written down so they can be transferred to the work site.

The blueprint made during transcription is called messenger RNA, or mRNA, because it acts as a messenger, bringing ideas from the DNA to the site of protein synthesis. If the architect's ideas change, then the blueprint would change as well. Similarly, if DNA is changed, the mRNA will change too.

Ribosomes and tRNA

After the blueprint has been made, it is sent off to the work site to be used to build the house. In the cell, the work site where proteins are made is called the ribosome. The ribosome will 'read' the mRNA and insert the appropriate amino acids. An amino acid is a unit used to build up a protein, like a piece of timber used to build up a house.

There are 20 amino acids that cells can use, and different combinations of these amino acids can make different proteins. Since most proteins are several hundred to thousands of amino acids long, you can imagine there are many, many different possible combinations.

How do the amino acids get to the ribosome? They are brought there by another type of RNA, called transfer RNA, or tRNA. tRNA is like a delivery truck bringing building materials to the ribosome job site.

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