Definition. Region in San Francisco, California that is considered to be the technology hub of the United States. The region is made up a number of computer companies and computer chip manufactures. The region gets its nickname from the silicon that is used in computer chips.Due to the demand for space in Silicon Valley, real estate and other property is very expensive and hard to find.he region is made up a number of computer companies and computer chip manufactures. The region gets its nickname from the silicon that is used in computer chips. Due to the demand for space in Silicon Valley, real estate and other property is very expensive and hard to find.
A substitution is a mutation that exchanges one base for another (i.e., a change in a single chemical letter such as switching an A to a G). Such a substitution could: 1  change a codon to one that encodes a different amino acid and cause a small change in the protein produced. 2  For example, sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced.
This image shows an example of missense mutation. One of the nucleotides (adenine) is replaced by another nucleotide (cytosine) in the DNA sequence. This results in an incorrect amino acid (proline) being incorporated into the protein sequence.In genetics, a missense mutation (a type of nonsynonymous substitution) is a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid.hen an amino acid may be encoded by more than one codon (so-called degenerate coding) a mutation in a codon may not produce any change in translation; this would be a silent mutation (a type of synonymous substitution, which is not always silent) and not a missense mutation.