What is a mutation?
A mutation is a permanent change in the DNA sequence of a gene. Mutations in a gene’s DNA sequence can alter the amino acid sequence of the protein encoded by the gene. How does this happen? Like words in a sentence, the DNA sequence of each gene determines the amino acid sequence for the protein it encodes. The DNA sequence is interpreted in groups of three nucleotide bases, called codons. Each codon specifies a single amino acid in a protein.
When a mutation occurs at one of the markers that we are examining, the number of repeats will increase or decrease, usually by one. For example, a father who is DYS19 = 10 may encounter a mutation at the level of his sperm which will change the DYS19 into 11 (an increase of 1). This new DYS19 is then introduced to his son, who will then pass the DYS19 = 11 to all of his sons. A mutation normally happens when the polymerase which copies the DNA in our body makes a slight mistake and does not copy the original exactly. All changes are then passed on to further generations. Mutations are extremely rare. The chances that a single Y-Chromosome marker will mutate is approximately once in every 500 generations. In a situation where 44 markers are examined, we would expect to see one mutation occurring in any one of the 44 markers every 11.4 generations (divide 500 by 44). The presence and detection of such mutations while you are conducting your research will allow you to determine how close
Mutation is a change in the original DNA sequence of a gene. Mutations come in different forms such as substitution of a nucleotide with another one, deletion of single or a group of nucleotides, insertion of one or more unnecessary nucleotides and so on. Mutations could potentially change the correct codes of the DNA and consequently result in a defective protein structure. A prevalent form of a mutation is substitution of a nucleotide by another one. Normal DNA sequence: Intermediate step: Completed mutation: ATAGGCTAGAATCC ATAAGCTAGAATCC ATAAGCTAGAATCC TATCCGATCTTAGG TATCCGATCTTAGG TATTCGATCTTAGG Substitution of an A for G in the original DNA sequence is a mutation and is completed by subsequent substitution of its complement from a C to a T.
A mutation is any change in the DNA sequence. Mutations can lead to genetic disorders or disease. Most mutations are recognised because the phenotype, that is the characteristics displayed by an organism, have changed. There are many different types of mutation. They can occur on a macroscopic level in the form of chromosomal mutations or they may be the result of a single base pair change in the DNA sequence. Mutations can occur within a gene preventing the synthesis of the correct protein, they may occur in gene promoter regions or in DNA regulatory regions changing the expression levels of the protein, or near the splice sites in introns causing disruption to the splicing process and production of an incorrect protein. Mutations are rare events occurring at a rate of 1 in every 50 million bases added to the nucleotide chain. Most of the changes that happen are quickly repaired by our very efficient and accurate DNA repair system. However, this repair mechanism is not foolproof. Fail
