Genetic Mutations
A mutation is a change in the genetic material that controls heredity. The genetic material is contained in chromosomes, which are divided into genes. Point mutations involve single genes and occur by substitution and insertion or deletion of a single base in DNA. Insertions or deletions, referred to as frameshift mutations, shift the reading of the code by one or more bases so that all amino acids produced after the addition or deletion are affected. Translation is a series of complex biochemical processes through which the genetic information in mRNA is converted into protein. Mutations do not always yield identical results. In the majority of instances, they are either harmful or have no effect. Although much less common, mutations with little effect can also occur. Point mutations are divided into two general categories: base-pair substitutions and base-pair insertions or deletions. A base-pair substitution is the replacement of one nucleotide and its partner from the complementary DNA strand with another pair of nucleotides. Certain base-pair substitutions are referred to as silent mutations because they have no effect on the protein coded for. Missense mutations, the most common ty
Translation is the process through which a cell interprets a genetic message and builds a protein accordingly. The message is contained in a series of codons along the transcribed mRNA, which is identical to the complementary DNA strand with the exception that thymine is replaced by uracil. The fact that each type of tRNA molecule associates a particular mRNA codon with a particular amino acid makes this entire process possible. As a tRNA molecule arrives at a ribosome, it bears a specific amino acid at one of its end. A triplet called the anticodon, which binds to a complementary codon on mRNA, is at the other end. The ribosome, with the aid of ribosomal enzymes, will then join the amino acids into a chain. Codon by codon, the genetic message is translated, as tRNAs deposit amino acids in the order prescribed. Most of the time mutations either have no perceptible effect at all, or are harmful. Coding genes map into proteins using the genetic code. The genetic code is redundant (the technical term is degenerate), i.e., different triplets of nucleotides will produce the same amino acid. Because of the redundancy a point mutation may have no effect at all on the protein being coded for; these are known as silent mutations. For example, if CCG mutated to CCA, the mRNA codon that used to be GGC would become GGU, and a glycine would still be inserted at the proper location in the protein. However, if the sequence is altered in a crucial area such as the active site, protein activity will be significantly
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Approximate Word count = 1045
Approximate Pages = 4 (250 words per page double spaced)
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