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Information about Point Mutation

A point mutation, or single base substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. One can categorize point mutations as follows:
  • transitions: replacement of a purine base with another purine or replacement of a pyrimidine with another pyrimidine
  • transversions: replacement of a purine with a pyrimidine or vice versa.
Transition mutations are about an order of magnitude more common than transversions. Point mutations can also be categorized functionally: For example, sickle-cell disease is caused by a single point mutation (a missense mutation) in the beta-hemoglobin gene that converts a GAG codon into GTG, which encodes the amino acid valine rather than glutamic acid.

Point mutations that occur in non-coding sequences are most often without consequences, although there are exceptions. If the mutated base pair is in the promoter sequence of a gene, then the expression of the gene may change. Also, if the mutation occurs in the splicing seat of an intron, then this may interfere with correct splicing of the transcribed pre-mRNA.

Sometimes the term point mutation is also used to describe insertions or deletions of a single base pair (which has more of an adverse effect on the synthesized protein due to the nucleotides' still being read in triplets, but in different frames: a mutation called a frameshift mutation).

Causes

Point mutations may arise from spontaneous mutations that occur during DNA replication. The rate of mutation may be increased by mutagens. Mutagens can be physical, such as radiation from UV rays, X-rays or extreme heat, or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA). Mutagens associated with cancers are often studied to learn about cancer and its prevention.

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mutations are changes to the base pair sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can occur deliberately
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Purine (1) is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines make up one of the two groups of nitrogenous bases. Pyrimidines make up the other group.
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Purine (1) is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines make up one of the two groups of nitrogenous bases. Pyrimidines make up the other group.
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Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring.[1] It is isomeric with two other forms of diazine.
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In genetics, a nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon, or a nonsense codon in the transcribed mRNA, and possibly a truncated, and often nonfunctional protein product.
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Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
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In genetics, missense mutations or nonsynonymous mutations are types of point mutations where a single nucleotide is changed to cause substitution of a different amino acid. This in turn can render the resulting protein nonfunctional.
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Silent mutations are DNA mutations that do not result in a change to the amino acid sequence of a protein. They may occur in a non-coding region (outside of a gene or within an intron), or they may occur within an exon in a manner that does not alter the final amino acid sequence.
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amino acid is a molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent.
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Sickle cells
Classification & external resources

Sickle-shaped red blood cells
ICD-10 D 57.
ICD-9 282.6

OMIM 603903
DiseasesDB 1206
MedlinePlus 000527
eMedicine emerg/26  

MeSH C15.378.071.141.150.
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Hemoglobin, also spelled haemoglobin and abbreviated Hb, is the iron-containing oxygen-transport metalloprotein in the red blood cells of the blood in vertebrates and other animals.
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For a non-technical introduction to the topic, see .
A gene is a locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions and/or other functional sequence regions.
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genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells.
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amino acid is a molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent.
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Valine (abbreviated as Val or V)[1] is an α-amino acid with the chemical formula HO2CCH(NH2)CH(CH3)2. L-Valine is one of 20 proteogenic amino acids. Its codons are GUU, GUC, GUA, and GUG.
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Glutamic acid or glutamate (abbreviated as Glu or E; Glx or Z represents either glutamic acid or glutamine), is the protonated form of glutamate (the anion). Glutamate is one of the 20 proteinogenic amino acids.
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promoter is a regulatory region of DNA located upstream (towards the 5' region) of a gene, providing a control point for regulated gene transcription.

Overview

The promoter contains specific DNA sequences that are recognized by proteins known as transcription factors.
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Introns, derived from the term "Intervening Sequences", are non-coding sections of DNA. Once this DNA section has been transcribed as a pre-mRNA sequence, the introns will be spliced out, then the mRNA will be translated into a protein.
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Genetic Insertion is the addition of one or more nucleotide base pairs into a genetic sequence. This can often happen in microsatellite regions due to the DNA polymerase slipping.
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frameshift mutation (also called a frameshift or a framing error) is a genetic mutation caused by indels, ie. inserts or deletes a number of nucleotides that is not evenly divisible by three from a DNA sequence.
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mutations are changes to the base pair sequence of the genetic material of an organism. Mutations can be caused by copying errors in the genetic material during cell division, by exposure to ultraviolet or ionizing radiation, chemical mutagens, or viruses, or can occur deliberately
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DNA replication is the process of copying a double-stranded DNA molecule. This process is important in all known life forms and the general mechanisms of DNA replication are not the same in prokaryotic and eukaryotic organisms.
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In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the frequency of mutations above the natural background level.
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Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. It is so named because the spectrum starts with wavelengths slightly shorter than the wavelengths humans identify as the color violet
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X-rays (or Röntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 PHz to 30 EHz. X-rays are primarily used for diagnostic radiography and crystallography.
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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
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