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DNA Translation

Translation is the synthesis of proteins from RNA. The process of translation occurs in the cytoplasm in the ribosomes. Ribosomes are small and large subunits that surround the mRNA. In the translation process, the messenger RNA is decoded to produce a specific polypeptide. This process uses and mRNA sequence as a template for the synthesis of a chain of amino acids to form a protein. The mechanism of translation takes place in four steps, activation, initiation., elongation and termination. 

DNA Translation

 

Definition

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Translation is the final step in the synthesis of proteins from DNA. Translation is the process of synthesis of proteins which is directed by a mRNA template. During the translation process amino acid molecules are linked together in the form a polypeptide chain which be later foled into a protein. It is the process where, cellular ribosomes form proteins. Translation is a process where, messenger RNA that is produced by transcription is interpret to produce a amino acid chain or polypeptide which will later fold to from a active protein. 

Steps

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The translation mechanism occurs in the cytoplasm. After the synthesis of the mRNA by the process of transcription the mRNA undergo a series of modifications before entering into the process of translation.

In the mRNA sequence, there are section or sequence of nucleotides that do not code for amino acids, these sequences are known as introns and are removed. To this mRNA molecule a poly-A tail, which consists of adenine bases is attached to one end of the mRNA and to the other end the GTP (guanosine triphosphate) cap is added. These series of modifications to the mRNA removes unwanted sections of the mRNA and also protects the ends of the molecule. The mRNA is ready to undergo all the process of translation with completion of these modifications. 

DNA Translation Steps

The process of translation is divided into three steps - Initiation, Elongation and Termination.  

Initiation 

  • The modified mRNA molecule is enters to the process of translation. The mRNA molecule binds to a ribosome on a specific site. 
  • Ribosomes are made up two units, one smaller subunit and one larger subunit. The ribosomes also have a specific site for the binding of the mRNA and two sites for the binding of the tRNA molecule.
  • An initiator tRNA molecule recognizes a specific codon sequence on the mRNA molecule and binds to the same sequence of the mRNA. A large subunit of the ribosome binds to this newly formed complex. 
  • The initiator tRNA molecule binds and resides to the P site of the ribosome leaving the other A site unbound or open. 
  • As the tRNA molecule recognizes the next codon on the mRNA molecules, it attaches to the A site on the ribosome. 
  • There is a formation of a peptide bond connecting the amino acid of the tRNA in the P site to the amino acid of the tRNA bound in the A site. 

Elongation 

  • As the ribosome moves along the mRNA molecule sequence, the tRNA molecule bound at the P site is unbound or released and the tRNA bound in the A site gets translocated to the P site of the ribosme. 
  • This translocation makes the A site of the ribosome vacant, it remains so until another tRNA molecule recognizes the new mRNA codon sequence and binds in to the open position. 
  • This process is a continuous pattern as the tRNA molecules are released from the complex and new tRNA molecules bind to the ribosome and the chain of amino acid grows. 
Elongation

Termination

  • The translation process is on with the ribosome translating the mRNA until it reaches a termination codon on the mRNA molecule. 
  • There is continuous growth of the protein chain during this process, this protein is called a polypeptide chain and it is released from the tRNA molecule and the ribosome regains back into its large and small subunits. 
  • The polypeptide chain which is newly formed undergoes several modifications before it becomes a fully functional protein.

Genetic Code

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Genetic code is a sequence of nucleotide bases of the DNA and RNA, these code for amino acids chains. Three nucleotide bases for an amino acid or they code for the initiation and termination of protein synthesis. Amino acids are linked together to form proteins. 

Genetic code is the information encoded with genetic material and is translated into proteins by the living cells. This decoding is done by ribosome which connects one amino acid to other using the tRNA molecules. The genetic code is similar among all organisms and can be expressed with 64 types. 
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