What is the role of DNA in the synthesis of protein?
DNA is divided into functional units called genes. A gene is a segment of DNA that codes for a functional product (mRNA, tRNA, or rRNA). Since the vast majority of genes are transcribed into mRNA and mRNA is subsequently translated into polypeptides or proteins, most genes code for protein synthesis.
The Central Dogma of Molecular Biology states that DNA makes RNA makes proteins (Figure 1). The process by which DNA is copied to RNA is called transcription, and that by which RNA is used to produce proteins is called translation.
- The next step in making a protein is called translation. This is when the RNA is converted (or "translated") into a sequence of amino acids that makes up the protein. The translation process of making the new protein from the RNA instructions takes place in a complex machine in the cell called the ribosome.
- The type of RNA that contains the information for making a protein is called messenger RNA (mRNA) because it carries the information, or message, from the DNA out of the nucleus into the cytoplasm. A type of RNA called transfer RNA (tRNA) assembles the protein, one amino acid at a time.
- A protein is made from amino acids, these form a strand. When the DNA was transcribed into RNA, one base of DNA corresponded to one base of RNA, this 1 to 1 relation is not used in the translation to protein. During this translation, 1 amino acid is added to the protein strand for every 3 bases in the RNA.
The three nucleotides in a codon are specific for a particular amino acid. The assembly of the polypeptide begins when a ribosome attaches to a start codon located on the mRNA. Then tRNA carries the amino acid to the ribosomes, which are made of rRNA and protein and have three bonding sites to promote the synthesis.
- protein synthesis occurs in cellular structures called ribosomes , found out-side the nucleus. The process by which genetic information is transferred from the nucleus to the ribosomes is called transcription. During transcription, a strand of ribonucleic acid (RNA) is synthesized.
- 5 steps of protein synthesis
- Copy of one side of DNA strand is made (called mRNA, messenger RNA)
- mRNA moves to cytoplasm, then ribosome.
- mRNA goes through ribosome 3 bases at a time.
- transfer RNA (tRNA) matches up with the open DNA bases.
- tRNA releases the amino acid at the top, which joins the chain of amino acids being produced.
- Steps in Protein Synthesis: STEP 1: The first step in protein synthesis is the transcription of mRNA from a DNA gene in the nucleus. At some other prior time, the various other types of RNA have been synthesized using the appropriate DNA. The RNAs migrate from the nucleus into the cytoplasm.
This copy of the DNA is called messenger RNA, or mRNA for short. Once it is made, the mRNA leaves the nucleus and moves to the ribosomes. It is at the ribosomes where the mRNA code is made into a protein through a process called translation. The mRNA code is "scanned" by the ribosome.
- Each protein is made up of large numbers of amino acid molecules. Each triplet of bases codes for one particular amino acid. Amino acids are made in the number and order dictated by the number and order of base triplets. Finally, the amino acid molecules join together in a long chain to make a protein molecule.
- Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein. These proteins bind and carry atoms and small molecules within cells and throughout the body.
- The nucleus is an organelle found in eukaryotic cells. Inside its fully-enclosed nuclear membrane, it contains the majority of the cell's genetic material. This material is organized as DNA molecules, along with a variety of proteins, to form chromosomes.
Updated: 23rd September 2018