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The genetic code

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Introduction

The genetic code I will discuss the genetic code, looking at the specific areas of transcription/translation, the codon/anticodon, mutation, sense/antisense, the non-overlapping codon and the intron. The genetic code is the base sequence of the DNA that has been copied to a base sequence in mRNA. "This sequence is the genetic code for a protein."1 This code is for a single amino acid, which is called a codon. The genetic code has two very important features. The first is a non-overlapping codon; this codon is a specific start codon, which ensures that the ribosome correctly 'read' the mRNA in a "unique way"1. This unique way is in sets of three, "64 triplets of nucleotides."3 For example: AUG AAU TCG CCU. The second feature is that the code is degenerate. This means some of the amino acids are coded for more than one codon. Transcription is the transfer of information from DNA to mRNA. ...read more.

Middle

This is the process of translation. Appropriate or different, specific tRNA carries corresponding amino acids."1 "The other "end" of the tRNA molecule has an "acceptor" site where the tRNA's specific amino acid will bind."4 Energy is needed to attach amino acids to the tRNA (ATP). So protein synthesis doesn't rely on the diffusion of amino acids, but does rely on transfer RNA (tRNA). Each tRNA molecule has three unpaired bases; these as a collective are called an 'anticodon'. The tRNA pairs with the mRNA the same way as before, matching with the codon in the ribosome. The tRNA bases pair with the mRNA bases A=U, C=G, G=C and U=A. The ribosome then removes the amino acids for the tRNA molecule and bonds it to the others. As the ribosome move along the mRNA three bases at a time, the ribosome will continue linking the amino acids brought there by the tRNA to form a protein molecule. ...read more.

Conclusion

Generally these differences do not make any impact on our health and are called polymorphism (poly means many; morphisms means forms). They are quite common. So while the genetic code may be slightly changed by having a polymorphism, the change has not significantly altered the gene message: the information is still understood by the cell. However, some changes to the genetic code in genes cause the message to be changed so that it is no longer understood by the cell: the gene is broken or faulty. Changes that make the genes faulty are called mutations. If the message to the cell comes from a faulty gene, the cell will not make the correct copy of the product, will make it in reduced amounts or will not make it at all. Faults in the genes may cause a problem with the development and functioning of different body systems or organs and result in a genetic disorder. Mutations that may be beneficial are that of immunity to a disease or a useful family trait. ...read more.

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