protein Synthesis

There are three different types of RNA

• mRNA
• rRNA
• tRNA

There are two main processes involved in making a Protein.

• Transcription - the Formation of mRNA
• Translation - the Translation of the code

DNA, which does not leave the nucleus, acts as a template or blueprint for the production of mRNA, which carries the instructions needed for Protein Synthesis from the nucleus to the cytoplasm. The function of the ribosome is to provide a suitable surface for the attachment of mRNA and then the assembly of protein.

• DNA acts as a template providing the instructions in the form of a long sequence of nucleotides.
• A complementary section of part of this sequence is made into mRNA by a process called Transcription.
• The mRNA acts as a template to which complementary tRNA molecules attach and the amino acids they carry are linked to form a polypeptide by a process called a Translation.

The basic process of Protein Synthesis occurs as follow:-

Transcription:

• The mRNA is copied from a specific region of DNA called Cistron.
• Often this is equivalent to a Gene and codes for a specific polypepetide.
• The Enzyme DNA HelicASE acts on a specific region of the DNA molecule (Cistron), to break the Hydrogen Bonds between bases, causing the two strands to seperate and expose the nucleotides bases in that region.
• The Enzyme RNA Polymerase links to the DNA at the beginning of the sequence to be copied. The double-stranded DNA first unwinds and then unzips in the relevant region. Only one of the DNA strand acts as a template against which a matching mRNA can be formed
• Transcription occurs when free RNA nucleotides then align themselves opposite one of the two strands. ( Template strand )
• Because of the complementary relationships between the bases in DNA and the free Nucleotides, Cytosine in the DNA attracts a Guanine, Guanine a Cytosine, Thymine an Adenine and Adenine an uracil
• In RNA no Thymine is present as Uracil replaces thymine.
• RNA Polymerase moves along the DNA forming bonds that…