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The DNA double helix is separated into 2 strands by DNA ligase (an enzyme).
21 December 2012
Next, transcription occurs, where a DNA strand is replicated for a mirror-copy of a strand with corresponding bases called RNA (ie C-G or A-T, except RNA uses Uracil instead of Thymine).
21 December 2012
The RNA molecule is able to leave the nucleus through the nuclear pores because it is smaller than DNA.
21 December 2012
The RNA molecule moves to a ribosome attached to rough endoplasmic reticulum (RER) where translation will occur.
21 December 2012
At this stage, it is important to think of sequences of 3 bases on the mRNA molecule as forming a 'triplet code' for one amino acid. Amino acids are present in the cytoplasm attached to transport RNA (tRNA) which includes a sequence of 3 bases. The RNA is fed through the ribosome which effectively 'reads' the mRNA. The first
21 December 2012
Hope that helps!
21 December 2012
3 bases on mRNA is called a codon and 3 bases on a tRNA (attached to an amino acid) is called an anticodon. The first 3 bases on the mRNA is a 'start codon' which tells the ribosome to start translation and the last 3 will be a 'stop codon' neither of these have a corresponding anticodon. In between them each sequence of 3 bases (codon) will result in the corresponding anticodon (and therefore amino acid) being lined up. As the amino acids line up in the order dictated by the mRNA, peptide bonds form between then, and you are left with a polypeptide (primary structure protein).
21 December 2012
A length (strand) of DNA contains numerous tiplet codes which make up the genes, which then determine the particular proteins to be made by the process of protein synthesis. Working backwards, a particular characteristic of our genetic makeup (eg eye colour, blood group) is determined by the presence of speicifc proteins. These proteins are long chains of amino acids each of which must be in a specific sequence within the chain (polmyer). Each of these amino acids and their specific location in the protein chain, is determined by the gene for the protein being processed. The information for this is coded in the gene - the sequence of triplet codes in DNA. Of course, the process of getting from DNA to protein takes a number of steps, and these have already been described above.
26 December 2012
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