Difference Between Protein Synthesis and DNA Replication

Main Difference – Protein Synthesis vs DNA Replication

Protein synthesis and DNA replication are two mechanisms where DNA is used as the starting material. DNA serves as the genetic material of most organisms, storing the required information for the growth, development, and functioning of the organism. The main difference between protein synthesis and DNA replication is that the protein synthesis is the production of a functional protein molecule based on the information in the genes whereas DNA replication is the production of an exact replica of an existing DNA molecule. The final result of protein synthesis is a functional protein molecule, but in DNA replication it is a DNA molecule.

Key Areas Covered

1. What is Protein Synthesis
      – Definition, Mechanism, Importance
2. What is DNA Replication
      – Definition, Mechanism, Importance
3. What are the Similarities Between Protein Synthesis and DNA Replication
      – Outline of Common Features
4. What is the Difference Between Protein Synthesis and DNA Replication
      – Comparison of Key Differences

Key Terms: DNA, DNA Replication, Genes, Messenger RNA (mRNA), Proteins, Protein Synthesis, Ribosomes

What is Protein Synthesis

Protein synthesis refers to a process by which a linear chain of amino acids is produced based on the information stored on a gene. This means genes carry the message of the amino acid sequence of proteins. Information about each amino acid is encoded in the gene based on the genetic code. A combination of three nitrogenous bases, which is known as a codon, carries the information about a particular amino acid. The process of protein synthesis is shown in figure 1.

Figure 1: Protein Synthesis

The three steps of protein synthesis are transcription, RNA processing, and translation. During transcription, DNA is transcribed into an mRNA molecule. RNA polymerase is the enzyme involved in transcription. It binds to the promoter for the initiation of transcription. As the enzyme elongates through the DNA template, a long mRNA molecule is synthesized. Once RNA polymerase reaches the terminator, the transcription is terminated. The final result of the transcription is a pre-mature mRNA molecule. RNA processing is the process that produces a mature RNA molecule. During the processing, a 5’ cap and a poly A tail are added to the mRNA; in eukaryotes, introns are removed by splicing the exons. The mature mRNA molecule is released to the cytoplasm in order to undergo translation. During translation, the information on the mRNA molecule is decoded for the synthesis of an amino acid sequence of a particular protein. Translation is facilitated by ribosomes. The corresponding amino acids are carried by tRNA molecules.

What is DNA Replication

DNA replication refers to a process of producing an identical copy of a double-stranded DNA molecule. Each strand of the double-stranded DNA molecule serves as a template for the synthesis of the new DNA molecule. Therefore, the double stranded DNA molecule should be unwounded prior to undergoing the replication. DNA replication occurs in a semi-conservative manner – each newly-synthesized, double-stranded DNA molecule contains an old DNA molecule. The process of DNA replication is shown in figure 2.

Figure 2: DNA Replication

Several enzymes such as helicase, RNA primase, and DNA polymerase are involved in DNA replication. DNA is unwound by helicase, producing the replication fork. RNA primase adds primers to the DNA template. Since DNA polymerase adds complementary base pairs to the template strand, the recruitment of DNA polymerase through the DNA template produces a complementary DNA strand. The newly synthesized strand is complementarily base-paired with the old strand.

Similarities Between Protein Synthesis and DNA Replication

• Both protein synthesis and DNA replication are two mechanisms to which DNA is involved in.
• Both protein synthesis and DNA replication occur inside the cell.
• Both protein synthesis and DNA replication are required for the growth, development, and functioning of organisms.
• The initial templates of both protein synthesis and DNA replication are an unwound DNA molecule.
• Both protein synthesis and DNA replication can make errors by the incorporation of incorrect precursor molecules.

Difference Between Protein Synthesis and DNA Replication

Definition

Protein Synthesis: Protein synthesis refers to a process by which a linear chain of amino acids is produced based on the information stored on a gene.

DNA Replication: DNA replication refers to a process of producing an identical copy of a double-stranded DNA molecule.

Mechanism

Protein Synthesis: Transcription and translation are the two processes involved in the protein synthesis.

DNA Replication: The production of an exact replica of an existing DNA molecule occurs in the DNA replication.

Occur in

Protein Synthesis: Protein synthesis occurs inside the nucleus as well as in the cytoplasm.

DNA Replication: DNA replication occurs inside the nucleus in eukaryotes and in the cytoplasm of prokaryotes.

RNA

Protein Synthesis: mRNA molecules are involved in protein synthesis apart from DNA.

DNA Replication: No RNA molecules are involved in DNA replication.

Enzymes

Protein Synthesis: The enzyme involved in the protein synthesis is RNA polymerase.

DNA Replication: Helicase, RNA primase, and DNA polymerase are the enzymes in DNA replication.

Final Product

Protein Synthesis: The final product of the protein synthesis is a protein molecule.

DNA Replication: The final product of the DNA replication is an exact replica of an existing DNA molecule.

Conclusion

Protein synthesis and DNA replication are two mechanisms where double-stranded DNA molecules are involved in the initial template. Protein synthesis is the synthesis of an amino acid sequence of a protein. DNA replication is the synthesis of a new DNA molecule from an existing DNA molecule. The main difference between protein synthesis and DNA replication is the mechanism and the final product of the two processes.

References:

1. Bailey, Regina. “Steps of DNA Replication.” ThoughtCo, Available here.
2. “Protein Synthesis.” SparkNotes, Available here.

Image Courtesy:

1. “Bacterial Protein synthesis” By Joan L. Slonczewski, John W. Foster – Microbiology: An Evolving Science (CC BY-SA 3.0) via Commons Wikimedia
2. “0323 DNA Replication” By OpenStax (CC BY 4.0) via Commons Wikimedia