What is Mutation
Mutation is permanent change of the nucleotide sequence of an organism. Mutation is a natural process over a long period of time. Mutation can be beneficial, neutral or harmful for the organism. Mutation do not "try" to supply what the organism "needs". Mutation is random.
Potential Causes of Mutation
There are many potential causes for mutation. Some of these include:
DNA fails to copy accurately
When the cell divides, the DNA copy may not be quite perfect. This small difference from the original DNA sequence is a mutation. As this happen over a long period of time, a organism can be evolved to adapt suited to its environment.
DNA fails to copy accurately
When the cell divides, the DNA copy may not be quite perfect. This small difference from the original DNA sequence is a mutation. As this happen over a long period of time, a organism can be evolved to adapt suited to its environment.
External Influence
Occurs when an organism are exposed to specific chemicals or radiation. These include tobacco, ultraviolet light and bromine. These are called mutagens which are physical or chemical agents that causes mutation. These agents causes the DNA to breakdown. This is not unnecessary a unnatural process. Even in the most isolated and pristine environment, DNA break downs. When the cell tries to repair, it may not do a perfect job which results in the DNA to be slightly different than the original DNA.
Occurs when an organism are exposed to specific chemicals or radiation. These include tobacco, ultraviolet light and bromine. These are called mutagens which are physical or chemical agents that causes mutation. These agents causes the DNA to breakdown. This is not unnecessary a unnatural process. Even in the most isolated and pristine environment, DNA break downs. When the cell tries to repair, it may not do a perfect job which results in the DNA to be slightly different than the original DNA.
Types of Mutation
There are many ways the DNA can be changed. These different type of mutations are:
Chromosomal Mutation
Chromosomal Mutation is an unpreidictable change that occurs in the chromosomes. These changes are most often caused during meiosis or by mutagens. Chromosomal mutation changes the number of chromosomes in a cell and/or changes the structure of the chromosomes. Some of these changes are harmful which can lead to development issues and even death.
Gene Mutation
Gene mutation is an alteration in the sequence of the nucleotides in the DNA. This change can affect a single nucleotide pair or larger segments of a chromosomes. Gene mutation can be categorised into 2 types: point mutation/substition and base pair insertion or deletion.
Chromosomal Mutation
Chromosomal Mutation is an unpreidictable change that occurs in the chromosomes. These changes are most often caused during meiosis or by mutagens. Chromosomal mutation changes the number of chromosomes in a cell and/or changes the structure of the chromosomes. Some of these changes are harmful which can lead to development issues and even death.
Gene Mutation
Gene mutation is an alteration in the sequence of the nucleotides in the DNA. This change can affect a single nucleotide pair or larger segments of a chromosomes. Gene mutation can be categorised into 2 types: point mutation/substition and base pair insertion or deletion.
Point Mutation/Substitution
occurs when a base is exchanged for another. The substitution can change a codon to one that encodes a different amino acid and cause a small change in the protein produced. It can change a codon to one that encodes the same amino acid and causes no change. These are called silent mutation. Subsitution can also change an amino acid coding codon to a single "stop" codon and cause an incomplete protein. An example can be seen on the image on the bottom. You can see the sequence "CTGGAG", the second last letter, A is replaced with G making it become "CTGGG".
occurs when a base is exchanged for another. The substitution can change a codon to one that encodes a different amino acid and cause a small change in the protein produced. It can change a codon to one that encodes the same amino acid and causes no change. These are called silent mutation. Subsitution can also change an amino acid coding codon to a single "stop" codon and cause an incomplete protein. An example can be seen on the image on the bottom. You can see the sequence "CTGGAG", the second last letter, A is replaced with G making it become "CTGGG".
Insertion
This occurs when an extra base pair is inserted into a new place in the DNA. The image below is an example of insertion. The sequence "CTGGAG" becomes "CTGGTGGAG" when "TGG" is inserted. This can be particularly hazardous if occurred in an exon, the amino acid coding region and can result in a numbers of genetic disorder.
This occurs when an extra base pair is inserted into a new place in the DNA. The image below is an example of insertion. The sequence "CTGGAG" becomes "CTGGTGGAG" when "TGG" is inserted. This can be particularly hazardous if occurred in an exon, the amino acid coding region and can result in a numbers of genetic disorder.
Deletion
Occurs when a section of a DNA is lost or deleted by accident.
Occurs when a section of a DNA is lost or deleted by accident.
Frameshift
Since DNA is divided into codons three base long, a Insertion or deletion can alter a gene so that the message is no longer correctly phrased.
For example pretend that the sentence, "The Fat Cat Ate" is sequence and each word represents a codon. If delete the first letter it becomes "Hef Atc Ata Te" which doesn't make sense. This generates truncated proteins that are useless as the sequence is no long informative.
Since DNA is divided into codons three base long, a Insertion or deletion can alter a gene so that the message is no longer correctly phrased.
For example pretend that the sentence, "The Fat Cat Ate" is sequence and each word represents a codon. If delete the first letter it becomes "Hef Atc Ata Te" which doesn't make sense. This generates truncated proteins that are useless as the sequence is no long informative.