From The School of Biomedical Sciences Wiki
Jump to navigation
Jump to search
|
|
| Line 1: |
Line 1: |
| Mutation is the change in [[DNA|DNA]] sequence of a cell due to errors in [[DNA|DNA]] replication or during [[Meiosis|meiosis]]. It can also be caused by environmental agents called [[Mutagens|mutagens]] though induced mutation. Mutagens are physical or chemical agents that lead to changes in genetic material of an organism. <br>There are various types of mutations.
| | See [[Mutation|Mutation]] |
| | |
| [[Point mutation|Point mutation]] is the addition or deletion of a single base pair within the [[DNA|DNA]]. It usually occurs through base substitution and even though it only causes a small change in [[DNA|DNA]] it can still have important consequences. <br>[[Silent mutation|Silent mutation]] is the change in [[Nucleotide|nucleotide]] sequence of a [[Amino acid|amino acid]] in a [[Polypeptide|polypeptide]]. Even though an [[Nucleotide|nucleotide]] sequence is changed it does not alter the [[Amino acid|amino acid]] of the [[Polypeptide|polypeptide]], this is because silent mutation only occurs in the third base of codons as genetic code is degenerate. As silent mutations does not affect the function of the protein it is considered as a neutral mutation.
| |
| | |
| [[Missense mutation|Missense mutation]] occurs through base substitution which changes a single [[Amino acid|amino acid]] in the [[Polypeptide|polypeptide]]. [[Missense mutation|Missense mutation]] can also be considered as a neutral mutation as it may not alter the function of the protein. They are not always neutral mutation and can also have a large effect on the function of the protein.
| |
| | |
| [[Nonsense mutation|Nonsense mutation]] is another mutation which can have a dramatic effect on the [[Polypeptide|polypeptides]] sequence. It affects the [[Codon|codons]] of the [[Polypeptide|polypeptide]], changing a normal codon to a [[Stop codon|stop codon]]. This causes early termination of translation resulting in a truncated [[Polypeptide|polypeptide]], which is less likely to function properly.
| |
| | |
| [[Frameshift mutation|Frameshift mutation]] can also have a dramatic effect on the [[Polypeptide|polypeptide]] sequence even causing inhibition of [[Protein|protein]] function. It involves addition or deletion of [[Nucleotides|nucleotides]] which are not in multiples of three. As [[Codon|codons]] come in multiples of three, frameshift causes a completely different amino acid sequence to be read downstream from point of mutation <ref>Robert J. Brooker, Eric P. Widmaier, Linda E. Graham, Peter D. Stilling. (2008) Biology, McGraw-Hill International Edition, New York: McGraw-Hill. Chapter 14, Page 278-283.</ref>.<br>
| |
| | |
| === References<br> ===
| |
| | |
| <references />
| |
| | |
| <br>
| |
Latest revision as of 21:29, 22 November 2011