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Process and Purpose of Protein Synthesis

Amanda Robb, Vibha Jha
  • Author
    Amanda Robb

    Amanda has taught high school science for over 10 years. She has a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. She is also certified in secondary special education, biology, and physics in Massachusetts.

  • Instructor
    Vibha Jha

    Vibha has doctorate in Immunology and has taught college level Microbiology

Learn what protein synthesis is, the process proteins are created by, the purpose of protein synthesis, and some functions of proteins, such as muscle contraction. Updated: 11/02/2021

Protein Synthesis

In biology, protein synthesis is an essential process that keeps cells functioning. The protein synthesis definition is the process that cells use to create proteins. Proteins are the building blocks of cells and "synthesis" means to make. So, protein synthesis is the process of making proteins.

Proteins are used for many structures and functions in the body. They include chemical messengers, like the hormone insulin, and contractile proteins like myosin that facilitate muscle contraction. Without proteins, cells would not have the structures or cellular machinery that they need to maintain an internal balance, or also known as homeostasis.

What Creates Proteins?

Proteins are created by ribosomes. Ribosomes are organelles found in the cytoplasm of cells. They read genetic material as instructions and assemble the amino acids in the right order. Amino acids are organic molecules that are the building blocks of proteins. The amino acids are linked together with peptide bonds through the process of dehydration synthesis. Thus, ribosomes are the protein manufacturing machinery of the cell.

Peptide bonds create the primary structure of proteins

Peptide bonds

Steps of Protein Synthesis

There are three main steps that lead to protein synthesis:

  1. Transcription
  2. Translation
  3. Post-translational modification

In eukaryotic cells, transcription occurs in the nucleus. The enzyme RNA polymerase reads the genetic code in DNA and makes a complementary copy called messenger RNA (mRNA). The RNA polymerase reads the four bases in DNA and adds the appropriate ribonucleotides. DNA uses adenine, guanine, cytosine and thymine. RNA uses adenine, guanine, cytosine and uracil. Adenine in DNA pairs with uracil in RNA and with thymine in DNA, and guanine pairs with cytosine in both RNA and DNA. The mRNA is then processed to include splicing, a 5' cap and a 3' poly-A-tail. The mature mRNA is then exported through the nucleus to the cytoplasm.

In the cytoplasm, translation occurs. During translation the ribosome's two subunits sandwich around the mRNA. The ribosome initiates protein synthesis and starts to read the mRNA message in groups of three nucleotides, called a codon. Each codon codes for one amino acid.

Another molecule, called transfer RNA (tRNA) helps to carry out elongation where amino acids are brought to the ribosome and the ribosome attaches them using peptide bonds. The tRNA molecules have a nucleotide sequence called an anticodon that allows them to pair with the complementary codon in mRNA. As this happens, the tRNA brings the amino acids to the ribosome and the ribosome catalyzes the dehydration reaction necessary to attach the amino acids together. When the ribosome reaches the stop codon, it releases the protein and the mRNA and translation is finished.

Translation is a step in protein synthesis where amino acids are added together to form a polypeptide chain

translation

However, proteins do not exist as long polypeptide chains. Rather, they will be folded into three dimensional shapes. So, after translation protein folding and another process, called post translational modification must occur. During protein folding, some proteins fold spontaneously and others need helpers called chaperone proteins to facilitate the process. In post-translational modification additional groups such as sugars, phosphates, or ubiquitin can be added onto the proteins to allow them to have full functionality. In addition, some proteins will be cut, or cleaved, using proteolysis.

The steps of protein synthesis are summarized in the table below:

Protein Creation

Protein synthesis is the process by which proteins are formed in biological cells. Proteins carry out all the important functions of a cell, such as transport, structural support, chemical reactions, cell communication, and protection from harmful bacteria and viruses. Every protein molecule is made up of amino acids. Amino acids are organic compounds containing carbon, hydrogen, oxygen, and nitrogen. There are only twenty amino acids that are naturally made by living organisms, but there are vast varieties of proteins created from them.

Names and abbreviations of amino acids

Protein creation begins with deoxyribonucleic acid, also known as DNA. The genetic code of the DNA dictates the type of protein synthesized. Transcription is the process in which the DNA's code is copied to produce ribonucleic acid, or RNA, in the nucleus of a cell. Three types of RNA work together to synthesize proteins: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). The RNA leaves the nucleus and ventures out into the cytoplasm to the ribosomes, which work like small factories that manufacture proteins.

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Peptide Chains

Peptide chains are long strings of amino acids. DNA, RNA, and ribosomes coordinate to form a peptide chain. The activity of producing a peptide chain is known as translation. First, the genetic code in the DNA is converted to the code present in the mRNA with the help of various enzymes. The code in the mRNA decides the order and type of amino acid used to make a peptide chain. Next, the ribosome attaches to the mRNA. The tRNA then carries the amino acid to the ribosome ready to synthesize a peptide chain. Each tRNA molecule attaches to its corresponding amino acid, creating amino-acyl tRNA.

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Video Transcript

Protein Creation

Protein synthesis is the process by which proteins are formed in biological cells. Proteins carry out all the important functions of a cell, such as transport, structural support, chemical reactions, cell communication, and protection from harmful bacteria and viruses. Every protein molecule is made up of amino acids. Amino acids are organic compounds containing carbon, hydrogen, oxygen, and nitrogen. There are only twenty amino acids that are naturally made by living organisms, but there are vast varieties of proteins created from them.

Names and abbreviations of amino acids

Protein creation begins with deoxyribonucleic acid, also known as DNA. The genetic code of the DNA dictates the type of protein synthesized. Transcription is the process in which the DNA's code is copied to produce ribonucleic acid, or RNA, in the nucleus of a cell. Three types of RNA work together to synthesize proteins: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). The RNA leaves the nucleus and ventures out into the cytoplasm to the ribosomes, which work like small factories that manufacture proteins.

Peptide Chains

Peptide chains are long strings of amino acids. DNA, RNA, and ribosomes coordinate to form a peptide chain. The activity of producing a peptide chain is known as translation. First, the genetic code in the DNA is converted to the code present in the mRNA with the help of various enzymes. The code in the mRNA decides the order and type of amino acid used to make a peptide chain. Next, the ribosome attaches to the mRNA. The tRNA then carries the amino acid to the ribosome ready to synthesize a peptide chain. Each tRNA molecule attaches to its corresponding amino acid, creating amino-acyl tRNA.

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Frequently Asked Questions

What does protein synthesis do to the body?

Protein synthesis produces proteins for the body. Protein synthesis is important because it creates structures that are needed for both individual cells and the body.

What is the meaning of protein synthesis?

The meaning of protein synthesis is to make proteins inside cells. Protein synthesis occurs in two main steps, transcription and translation.

What is the purpose of protein synthesis?

The purpose of protein synthesis is to make proteins for the cell and for the body. Proteins are important for carrying out chemical reactions, creating structures, acting as signaling molecules and more.

What are the 3 stages of protein synthesis?

The three stages of protein synthesis are transcription, translation, and post translational modification. During transcription, DNA is copied to mRNA. During translation mRNA is read to create a protein. Then, in post translational modification the protein is modified.

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