Are Proteins Synthesized From DNA? 7+ Facts You Should Know


In this article, we get know about 8 Important Facts regarding ‘Are proteins synthesized from DNA’ , along with central dogma of molecular biology.

The manufacturing of proteins is known as protein synthesis. When applied to biological systems, it occurs inside the cell. It takes place inside prokaryotic cytoplasm. As in eukaryotes, the coding section of the DNA is first translated into a transcript (mRNA) in the nucleus. Ribosomes transform the transcript into a protein complex with a predetermined amino acid sequence after it has left the nucleus.

The process through which cells make proteins using DNA, RNA, and several enzymes is known as protein synthesis. It often comprises protein folding, modifications, and proteolysis as well as transcription, translation, and post-translational processes.

Let us discuss some facts and try to understand Are Proteins Synthesized from DNA?

  • How protein is synthesized from DNA?
  • When is protein synthesized from DNA?
  • Where is protein synthesized from DNA?
  • Can protein be synthesized without DNA?
  • Does DNA direct protein synthesis?
  • How DNA directs protein synthesis?
  • Is protein synthesized from RNA?
  • Are proteins synthesized from mRNA?

Prokaryotic vs. Eukaryotic Protein Synthesis

  • A crucial class of biomolecules needed by all living things for survival are proteins. Prokaryotes and eukaryotes both manufacture proteins for a number of activities and functions. While some of the proteins serve as catalysts for biological reactions, certain proteins are used for structural functions.
  • Protein synthesis in prokaryotes and eukaryotes differs significantly. For instance, prokaryotes’ cytoplasm is where protein production takes place. The initial stage (transcription) takes place in the nucleus in eukaryotes. After forming, the transcript (mRNA) reaches the cytoplasm, which is where ribosomes are located.
  • Here, an amino acid chain is produced from the mRNA. The distinctions between bacterial and eukaryotic protein synthesis are displayed in below.

Key differences

Prokaryotic protein synthesisEukaryotic protein synthesis
Translation starts even before mRNA transcription completesEukaryotic protein synthesis involves transcription, followed by translation
Bacterial mRNA production does not involve the insertion of a cap and a poly A tail, with the exception of archaebacteriaThe insertion of a poly A tail and a 5′ cap to the 3′ end of the mRNA transcript.
At the AUG codon, translation begins; PIF-1, PIF-2, and PIF-3 are the initiating factors.The 5′ cap, which, at the first AUG codon, connects the mRNA to the ribosomal unit, triggers the start of translation;
PIF-1, PIF-2, and PIF-3 are the initiating factors.eIF1-6, eIF4B, eIF4C, eIF4D, and eIF4F are the initiating factors.
Differences between Prokaryotic v/s Eukaryotic protein synthesis

How protein is synthesized from DNA?

This amazing work of art illustrates the synthesis of proteins, a procedure that takes place in the cells of all living things. Transcription and translation are the two processes that make up the process known as protein synthesis.

Eukaryotic cells’ nuclei are where transcription occurs. During transcription, a messenger RNA molecule is created using DNA as a template (mRNA). The translation process begins at a ribosome in the cytoplasm after the mRNA molecule exits the nucleus. During translation, the genetic code present in mRNA is accessed and used to produce a protein. The fundamental tenet of molecular biology, DNA→  RNA→  Protein, sums together these 2 processes.

Transcription

The first element of the fundamental tenet of molecular biology is transcription: DNA → RNA. Transferring genetic information from DNA to mRNA is what it is called. A strand of mRNA is created during transcription to complement a strand of DNA.

Steps of Transcription

The three phases of transcription are initiation, elongation, and termination. The following diagram shows the steps.

  1. Initiation is the first step in transcription. It takes place when the promoter, a region of a gene, interacts with the RNA polymerase enzyme. In order for the enzyme to “read” the bases in one of the DNA strands, this signals the DNA to unwind. The enzyme is ready to assemble a complementary base-sequenced mRNA strand.
  2. Adding nucleotide sequences to the mRNA strand is referred to as elongation.
  3. Transcription comes to an end after termination. When the mRNA strand is completed, it separates from the DNA.

 

Processing mRNA

In eukaryotes, the newly transcribed mRNA is not yet ready for translation. Pre-mRNA at this level requires additional processing before evolving into mature mRNA and leaving the nucleus. The processing could involve polyadenylation, editing, and splicing. The mRNA is altered in various ways by these mechanisms. One gene can now produce several proteins because to these changes.

  • As may be seen in the diagram below, splicing eliminates introns from mRNA. The genome contains regions called introns that lack protein coding. Exons are the only parts of the remaining mRNA that really code for the protein. The diagram depicts the ribonucleoproteins, which are tiny proteins that make up the RNA in the nucleus and are essential for the splicing process.
  • Some of the nucleotides in mRNA are altered during editing. For instance, editing has resulted to the development of two distinct variants of the human protein (APOB), which helps in the transportation of lipids in the blood. Because of the early stop signal, that editing adds to mRNA, one variant is smaller than another.
  • The mRNA gains a “tail” through polyadenylation. In the tail, there is a row of As (adenine bases). It shows that the mRNA has finished. Additionally, it protects mRNA from enzymes that would break it down and helps the transfer of mRNA from the nucleus.

Translation

The second component of the fundamental tenet of molecular biology is translation: RNA→  Protein. It is a procedure through which mRNA’s genetic information is recited in order to produce a protein. The figure below demonstrates how translation works. mRNA proceeds to a ribosome, that is composed of proteins and rRNA, after leaving the nucleus. The ribosome interprets the string of codons in the mRNA after receiving the amino acids from tRNA molecules in the correct order.

  • You must learn more about tRNA’s structural makeup in order to comprehend its function. The amino acid that each tRNA molecule carries is represented by an anticodon.
  • An anticodon is a supplementary amino acid codon. For instance, because the amino acid lysine has the codon AAG, its anticodon is UUC.
  • As a consequence, a tRNA molecule through the anticodon UUC would transport lysine. A UUC anticodon of tRNA momentarily binds to any location where the codon AAG follows in the mRNA. The amino acid in tRNA is forfeited when it is linked to mRNA.
  • A polypeptide chain is created as amino acids are brought one at a time to the ribosome with the help of rRNA. Until a stop codon is reached, the chain of amino acids continues to develop.
Are proteins synthesized from DNA
Protein biosynthesis; central dogma of molecular biology from Wikipedia

What happens after translation?

Translation is frequently just the initial stage of a protein’s life cycle. Sometimes a protein must undergo moderate to significant post-translational modification.

For example,

  • Not all polypeptide chains can be deemed “completed” proteins without the addition of additional components. Other polypeptides require the removal of certain regions through a procedure known as proteolysis.
  • Often, this includes deleting the chain’s initial amino acid (typically methionine, by way of the specific amino acid designated by the start codon).

When is protein synthesized from DNA?

During transcription, a messenger RNA molecule is created using DNA as a template (mRNA). The translation process begins at a ribosome in the cytoplasm after the mRNA molecule exits the nucleus. During translation, the genetic code present in mRNA is accessed and used to produce a protein.

Are proteins synthesized from DNA
RNA polymerase is shown converting the template strand of DNA into the pre-mRNA molecule from Wikipedia

Where is protein synthesized from DNA?

While most protein synthesis takes place in the cell’s cytoplasm, the majority of its DNA is found in the nucleus (a small % in the mitochondria). Genetic information is transmitted from the nucleus into the cytoplasm via a message because DNA molecules are too big to fit through the nuclear membrane.

Ex: Messenger RNA (mRNA; ribonucleic acid) molecules, which are small single-stranded nucleic acids that convey this message through the coding regions of specific genes. Because the DNA sequence of a certain gene is actually translated into a corresponding RNA, the process of information transfer from DNA to mRNA takes place in the nucleus and is known as transcription.

Can protein be synthesized without DNA?

Results of a recent study revealed that messenger RNA (mRNA), which is known to contain the information for the assembly of the amino acids, is not necessary for the assembly of amino acids that are considered as the building blocks of protein.

Ex: It has long been accepted information in molecular biology that the DNA acts as the blueprint that transmits the instructions for producing proteins inside the body. However, fresh study discoveries disprove this conventional thinking by showing that some proteins have the capacity to produce other proteins.

Does DNA direct protein synthesis?

Your cells and practically every other organism include DNA as its main genetic component. It is employed in the multi-step process of protein synthesis, which transforms the DNA’s coded message into a useable protein molecule.

How DNA directs protein synthesis?

Translation is carried out by ribosomes which are either present in the cytoplasm or connected to the endoplasmic reticulum. Therefore, a protein’s production is controlled by the data contained in its DNA with the aid of messengers (mRNA) and translators (tRNA). DNA is converted to RNA in the nucleus. The message is carried by the mRNA from the nucleus to the cytoplasmic ribosome, where it is translated into a protein by the tRNA.

Are proteins synthesized from DNA
The central dogma depicts transcription from DNA code to RNA code to proteins in the second step encompassing protein creation from Wikipedia

Steps involved:

  • The majority of genes provide the information needed to build the useful molecules known as proteins. (A few genes produce regulatory materials that help the cell make proteins.) The process of going from gene to protein inside each cell is intricate and under strict supervision.
  • Transcriptions and translation are the two main steps. Transcription and translation work together to produce gene expression.
  • The information contained in a gene’s DNA is transferred to a similar molecule called RNA (ribonucleic acid) in the cell nucleus during transcription.
  • RNA and DNA both consist of a series of nucleotide building units, despite the fact that their chemical makeups differ slightly from one another.
  • Because messenger RNA (mRNA) transmits information from the nucleus to the cytoplasm, it is this type of RNA that contains the instructions needed to make a protein.
  • The cytoplasm is where translation, the second step in turning a gene into a protein, takes place. The ribosome, a specialised complex that “reads” the nucleotide sequence of the mRNA, interacts with the messenger RNA (mRNA).
  • Three nucleotide sequences make up a codon, which typically codes for one amino acid. (Amino acids are the building blocks of proteins.) One amino acid at a time, transfer RNA (tRNA), a kind of RNA, assembles the protein.
  • Protein synthesis continues until a “stop” codon is encountered by the ribosome (an arrangement of 3 nucleotides that doesn’t code for an amino acid).

The transfer of information from DNA to RNA to proteins is one of the fundamental ideas in molecular biology. It is usually referred to as the “central dogma” due to its importance.

Is protein synthesized from RNA?

The catalytic mechanisms of protein synthesis, which entail joining amino acids to form protein molecules, are governed by the ribosome’s rRNA molecules. To denote this role, rRNA is frequently referred to as a ribozyme or catalytic RNA.

Are proteins synthesized from mRNA?

During transcription, DNA serves as a template for the construction of a messenger RNA molecule (mRNA). The mRNA molecule travels to a cytoplasmic ribosome where translation occurs after leaving the nucleus. The genetic code found in the mRNA is analysed and used to make a protein during translation.

Ex: The genetic coding rules transform the nucleotide sequence of a gene into the amino acid sequence of a protein via the medium of mRNA.

  • Protein synthesis is the process through which cells produce proteins. The two steps are transcription and translation.
  • Transcription is the process through which genetic information in DNA is transformed into mRNA in the nucleus. The initiation, elongation, and termination make up its three steps. Once the instructions have been broken down, the mRNA sends them to a ribosome in the cytoplasm.
  • Translation takes place on the ribosome, which is made up of proteins and rRNA. The mRNA instructions are read during translation, and the tRNA sends the correct sequence of amino acids to the ribosome. Then, rRNA contributes to the formation of amino acid connections that result in a polypeptide chain.
  • A polypeptide chain may undergo additional processing after being synthesised to produce the completed protein.

Conclusion

In the above article, we studied about transcription, translation and Role of DNA/RNA in protein synthesis. Steps involved in the process of ‘Translation’ – central dogma of molecular biology.

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