Rebecca Johnson                Biology

                Mr. Donohue

The Genetic Code Essay Question

The Genetic Code is made up of the nucleic acids Deoxyribose (DNA) and Ribose (RNA), which are polymers of nucleotides. A nucleotide is a section of DNA made up of three molecules, a five-carbon sugar, a phosphoric acid molecule and a nitrogen containing organic base, which are all joined by condensation reactions.  DNA differs from RNA in a number of ways. Firstly DNA consists of two polynucleotide strands, which are joined together by hydrogen bonding which forms a double helix, whereas RNA consists of one single polynucleotide strand. In DNA there are the four bases in Cytosine, Guanine, Thymine and Adenine, whereas in RNA Thymine is replaced by Uracil. The bases join together according to complementary base pairing, A to T/U and C to G, because this is the correct length. The DNA helix is a store of genetic information controlling the synthesis of proteins and the development and structure of them. The sequence of three nucleotide bases is called a base triplet and each of these triplets’ codes for the 20 commonly occurring amino acids in living organisms. The base triplets of mRNA are known as codons and the genetic code is degenerate because some amino acids are coded for by more than one codon.

The Genetic code has to undergo DNA replication because this is essential for the growth and reproduction of organisms. DNA replication occurs by a semi-conservative mechanism. When DNA replicates the double helix uncoils into two separate strands, as hydrogen bonds between the polynucleotide strands are broken. Each of the strands acts as a template for the formation of a new complementary strand. Nucleotides bind to each template strand by specific base pairing and they are joined together by the enzyme DNA polymerase to form a polynucleotide strand. The two new DNA molecules are identical to each other and to the original DNA and the new-formed DNA molecule contains one of the original polynucleotide strands; therefore this is called semi-conservative replication.

Join now!

Protein synthesis is the process, which produces the proteins, which make up the Genetic Code, and this consists of two processes, which are transcription and translation. Transcription happens in the nucleus and during this the section of the DNA molecule (a gene) uncoils and the two polynucleotide strands separate, as hydrogen bonds are broken. RNA nucleotides line up against the DNA nucleotide bases on the template strand by specific complementary base pairing. RNA polymerase enzyme joins the nucleotides together to form a strand of messenger RNA. This mRNA leaves through the nuclear pore and attaches to a ribosome in ...

This is a preview of the whole essay