Describe the consequences of base substitution mutation with regards to sickle cell anaemia

In every gene, a sequence of three nucleotide bases will code for an amino acids, many of which form a protein. Within the normal gene for haemoglobin, the sequence of bases will code to produce amino acids and thus normal haemoglobin proteins (this will enable red blood cells to carry oxygen effectively). A substitution is the replacement of one or multiple bases with different ones. This is caused by errors in DNA replication as a result of a mutagen, an agent that causes genetic mutation, such as X-rays or UV radiation. With sickle cell anaemia, the normal DNA nucleotide sequence is altered from CTC to CAC. This means that when the DNA is translated, there is an alteration in the mRNA from GAG to GUG. This means that instead of the normal haemoglobin protein, Glutamic Acid, being produced, Valine is produced. Valine causes red blood cells to become "sickle" shaped and reduces the ability for the cell to take up oxygen. This can eventually lead to organ degeneration.