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Encyclopedia > Mutation
Part of the Biology series on
Evolution
Mechanisms and processes

Adaptation
Genetic drift
Gene flow
Mutation
Natural selection
Speciation In linguistics, apophony (also ablaut, gradation, alternation, internal modification, stem modification, stem alternation, replacive morphology, stem mutation, internal inflection) is the alternation of sounds within a word that indicates grammatical information (often inflectional). ... Mutation is an English word that derives from the latin word Mutatione, which means changes or modifications. ... For the song by Girls Aloud see Biology (song) Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, speech lit. ... This article is about evolution in biology. ... Image File history File links Tree_of_life. ... For other uses, see Adaptation (disambiguation). ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... In population genetics, gene flow (also known as gene migration) is the transfer of alleles of genes from one population to another. ... For other uses, see Natural selection (disambiguation). ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ...

Research and history

Evidence
Evolutionary history of life
History
Modern synthesis
Social effect / Objections While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... Evolutionary thought has roots in antiquity as philosophical ideas conceived during the Ancient Greek and Roman eras, but until the 18th century, biological thought was dominated by essentialism, the idea that living forms are static and unchanging in time. ... The modern evolutionary synthesis refers to a set of ideas from several biological specialities that were brought together to form a unified theory of evolution accepted by the great majority of working biologists. ... The theory of transmutation had early origins in the speculations and hypotheses of Erasmus Darwin, and Jean-Baptiste Lamarck. ... There have been numerous objections to evolution since alternative evolutionary ideas came to be hotly debated around the start of the nineteenth century. ...

Evolutionary biology fields

Cladistics
Ecological genetics
Evolutionary development
Human evolution
Molecular evolution
Phylogenetics
Population genetics
It has been suggested that Clade be merged into this article or section. ... Ecological genetics is the study of genetics (itself a field of biology) from an ecological perspective. ... Evolutionary developmental biology (evolution of development or informally, evo-devo) is a field of biology that compares the developmental processes of different animals in an attempt to determine the ancestral relationship between organisms and how developmental processes evolved. ... For the history of humans on Earth, see History of the world. ... Molecular evolution is the process of the genetic material in populations of organisms changing over time. ... Phylogenetic groups, or taxa, can be monophyletic, paraphyletic, or polyphyletic. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ...

Biology Portal · v  d  e 

In biology, mutations are changes to the nucleotide 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 under cellular control during processes such as hypermutation. In multicellular organisms, mutations can be subdivided into germ line mutations, which can be passed on to descendants, and somatic mutations, which are not transmitted to descendants in animals. Plants sometimes can transmit somatic mutations to their descendants asexually or sexually (in case when flower buds develop in somatically mutated part of plant). A new mutation that was not inherited from either parent is called a de novo mutation. The source of the mutation is unrelated to the consequence, although the consequences are related to which cells are affected. For the song by Girls Aloud see Biology (song) Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, speech lit. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... Genetic material is used to store the genetic information of an organic life form. ... This does not adequately cite its references or sources. ... For other uses, see Ultraviolet (disambiguation). ... Radiation hazard symbol. ... In biology, a mutagen (Latin, literally origin of change) is an agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... A common alternate meaning of virus is computer virus. ... This article needs to be cleaned up to conform to a higher standard of quality. ... A Germline Mutation is any detectable, heritable variation in the lineage of germ cells. ...


Mutations create variations in the gene pool. Less favorable (or deleterious) mutations can be reduced in frequency in the gene pool by natural selection, while more favorable (beneficial or advantageous) mutations may accumulate and result in adaptive evolutionary changes. For example, a butterfly may produce offspring with new mutations. The majority of these mutations will have no effect; but one might change the color of one of the butterfly's offspring, making it harder (or easier) for predators to see. If this color change is advantageous, the chance of this butterfly surviving and producing its own offspring are a little better, and over time the number of butterflies with this mutation may form a larger percentage of the population. The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. ... For other uses, see Natural selection (disambiguation). ... This article is about evolution in biology. ...


Neutral mutations are defined as mutations whose effects do not influence the fitness of an individual. These can accumulate over time due to genetic drift. It is believed that the overwhelming majority of mutations have no significant effect on an organism's fitness. Also, DNA repair mechanisms are able to mend most changes before they become permanent mutations, and many organisms have mechanisms for eliminating otherwise permanently mutated somatic cells. The neutral theory of molecular evolution (also, simply the neutral theory of evolution) is an influential theory that was introduced with provocative effect by Motoo Kimura in the late 1960s and early 1970s. ... Fitness (often denoted in population genetics models) is a central concept in evolutionary theory. ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... DNA damage resulting in multiple broken chromosomes DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. ... This article does not cite any references or sources. ...


Mutation is generally accepted by the scientific community as the mechanism upon which natural selection acts, providing the advantageous new traits that survive and multiply in offspring or disadvantageous traits that die out with weaker organisms.

Contents

Classification

By effect on structure

Illustrations of five types of chromosomal mutations.
Illustrations of five types of chromosomal mutations.

The sequence of a gene can be altered in a number of ways. Gene mutations have varying effects on health depending on where they occur and whether they alter the function of essential proteins. Structurally, mutations can be classified as: Description: Different types of mutation Source: [1] (file) License: All of the illustrations in the Talking Glossary of Genetics are freely available and may be used without special permission. ... Description: Different types of mutation Source: [1] (file) License: All of the illustrations in the Talking Glossary of Genetics are freely available and may be used without special permission. ...

  • Small-scale mutations, such those as affecting a small gene in one or a few nucleotides, including:
    • Point mutations, often caused by chemicals or malfunction of DNA replication, exchange a single nucleotide for another[1]. Most common is the transition that exchanges a purine for a purine (A ↔ G) or a pyrimidine for a pyrimidine, (C ↔ T). A transition can be caused by nitrous acid, base mis-pairing, or mutagenic base analogs such as 5-bromo-2-deoxyuridine (BrdU). Less common is a transversion, which exchanges a purine for a pyrimidine or a pyrimidine for a purine (C/T ↔ A/G). A point mutation can be reversed by another point mutation, in which the nucleotide is changed back to its original state (true reversion) or by second-site reversion (a complementary mutation elsewhere that results in regained gene functionality). These changes are classified as transitions or transversions[2]. An example of a transversion is adenine (A) being converted into a cytosine (C). There are also many other examples that can be found. Point mutations that occur within the protein coding region of a gene may be classified into three kinds, depending upon what the erroneous codon codes for:
    • Insertions add one or more extra nucleotides into the DNA. They are usually caused by transposable elements, or errors during replication of repeating elements (e.g. AT repeats). Insertions in the coding region of a gene may alter splicing of the mRNA (splice site mutation), or cause a shift in the reading frame (frameshift), both of which can significantly alter the gene product. Insertions can be reverted by excision of the transposable element.
    • Deletions remove one or more nucleotides from the DNA. Like insertions, these mutations can alter the reading frame of the gene. They are generally irreversible: though exactly the same sequence might theoretically be restored by an insertion, transposable elements able to revert a very short deletion (say 1-2 bases) in any location are either highly unlikely to exist or do not exist at all. Note that a deletion is not the exact opposite of an insertion: the former is quite random while the latter consists of a specific sequence inserting at locations that are not entirely random or even quite narrowly defined.
  • Large-scale mutations in chromosomal structure, including:
    • Amplifications (or gene duplications) leading to multiple copies of all chromosomal regions, increasing the dosage of the genes located within them.
    • Deletions of large chromosomal regions, leading to loss of the genes within those regions.
    • Mutations whose effect is to juxtapose previously separate pieces of DNA, potentially bringing together separate genes to form functionally distinct fusion genes (e.g. bcr-abl). These include:
      • Chromosomal translocations: interchange of genetic parts from nonhomologous chromosomes.
      • Interstitial deletions: an intra-chromosomal deletion that removes a segment of DNA from a single chromosome, thereby apposing previously distant genes. For example, cells isolated from a human astrocytoma, a type of brain tumor, were found to have a chromosomal deletion removing sequences between the "fused in glioblastoma" (fig) gene and the receptor tyrosine kinase "ros", producing a fusion protein (FIG-ROS). The abnormal FIG-ROS fusion protein has constitutively active kinase activity that causes oncogenic transformation (a transformation from normal cells to cancer cells).
      • Chromosomal inversions: reversing the orientation of a chromosomal segment.
    • Loss of heterozygosity: loss of one allele, either by a deletion or recombination event, in an organism that previously had two different alleles.

A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... In genetics, a Transition is a mutation changing a purine to another purine nucleotide (A <-> G) or a pyrimidine to another pyrimidine nucleotide (C <-> T). ... Purine (1) is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. ... 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. ... Nitrous acid (molecular formula HNO2) is a weak monobasic acid known only in solution and in the form of nitrite salts. ... BrdU, also known as 5-bromo-2-deoxyuridine, is a base analog of thymidine, with the thymine substituted by bromouracil. ... In molecular biology, Transversion refers to the substitution of a purine for a pyrimidine or vice versa. ... For the programming language Adenine, see Adenine (programming language). ... Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... RNA codons. ... Silent mutations or synonymous mutations are DNA mutations that, although they alter a particular codon, they do not alter the final amino acid, and hence do not affect the final protein. ... This article is about the class of chemicals. ... 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. ... In genetics, a nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon (also called a nonsense codon) in the transcribed mRNA, and possibly a truncated (and often nonfunctional) protein product. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... An illustration of an insertion at chromosome level At DNA level, an insertion means the insertion of a few base pairs into a genetic sequence. ... Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called Transposition. ... In genetics, splicing is a modification of genetic information after transcription, in which introns of precursor messenger RNA (pre-mRNA) are removed and exons of it are joined. ... The interaction of mRNA in a eukaryote cell. ... A Splice site mutation is a genetic mutation that inserts or deletes a number of nucleotides in the specific site at which splicing of an intron takes place during the processing of precursor messenger RNA into mature messenger RNA. The abolishment of the splicing site results in one or more... In biology, a reading frame is a contiguous and non-overlapping set of three-nucleotide codons in DNA or RNA. There are 3 possible reading frames in a strand. ... Framing error is the following: Generally, a framing error is the result of reading a string of symbols which are grouped in blocks starting at the wrong point. ... Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called Transposition. ... A genetic deletion is a genetic aberration in which part of a chromosome is missing. ... In biology, a reading frame is a contiguous and non-overlapping set of three-nucleotide codons in DNA or RNA. There are 3 possible reading frames in a strand. ... A scheme of a condensed (metaphase) chromosome. ... Schematic of a region of a chromosome before and after a duplication event Gene duplication occurs when an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome leads to the duplication of a region of DNA containing a gene [1]. The significance of this process for... A genetic deletion is a genetic aberration in which part of a chromosome is missing. ... A fusion gene is a hybrid gene formed from two previously separate genes. ... A karyotype showing translocation 9;22 Philadelphia chromosome or Philadelphia translocation is a specific genetic, chromosomal abnormality that is associated with chronic myelogenous leukemia (CML). ... Chromosomal translocation of the 4th and 20th chromosome. ... Astrocytomas are primary intracranial tumors derived from astrocytes cells of the brain. ... An inversion is a chromosome rearrangement in which a segment of a chromosome is reversed end to end. ... Loss of heterozygosity in a cell represents the loss of a single parents contribution to part of its genome. ... An allele (pronounced , ) (from the Greek αλληλος, meaning each other) is one member of a pair or series of different forms of a gene. ... Recombination usually refers to the biological process of genetic recombination and meiosis, a genetic event that occurs during the formation of sperm and egg cells. ...

By effect on function

  • Loss-of-function mutations are the result of gene product having less or no function. When the allele has a complete loss of function (null allele) it is often called an amorphic mutation. Phenotypes associated with such mutations are most often recessive. Exceptions are when the organism is haploid, or when the reduced dosage of a normal gene product is not enough for a normal phenotype (this is called haploinsufficiency).
  • Gain-of-function mutations change the gene product such that it gains a new and abnormal function. These mutations usually have dominant phenotypes. Often called a neo-morphic mutation.
  • Dominant negative mutations (also called anti-morphic mutations) have an altered gene product that acts antagonistically to the wild-type allele. These mutations usually result in an altered molecular function (often inactive) and are characterised by a dominant or semi-dominant phenotype. In humans, Marfan syndrome is an example of a dominant negative mutation occurring in an autosomal dominant disease. In this condition, the defective glycoprotein product of the fibrillin gene (FBN1) antagonizes the product of the normal allele.
  • Lethal mutations are mutations that lead the death of the organisms which carry the mutations.

A null allele is an allele with the effect of either absence of the gene product at the molecular level, or the absence of function at the phenotypic level. ... 1946 Nobel Prize winner Hermann J. Muller (1890-1967) coined the terms amorph, hypomorph, hypermorph, antimorph and neomorph to classify mutations based on their behaviour in various genetic situations. ... In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ... Haploid (meaning simple in Greek) cells have only one copy of each chromosome. ... Haploinsufficiency occurs when a diploid organism only has a single functional copy of a gene (with the other copy inactivated by mutation) and the single functional copy of the gene does not produce enough of a gene product (typically a protein) to bring about a wild-type condition, leading to... In genetics, the term dominant gene refers to the allele that causes a phenotype that is seen in a heterozygous genotype. ... 1946 Nobel Prize winner Hermann J. Muller (1890-1967) coined the terms amorph, hypomorph, hypermorph, antimorph and neomorph to classify mutations based on their behaviour in various genetic situations. ... 1946 Nobel Prize winner Hermann J. Muller (1890-1967) coined the terms amorph, hypomorph, hypermorph, antimorph and neomorph to classify mutations based on their behaviour in various genetic situations. ... In genetics, the term dominant gene refers to the allele that causes a phenotype that is seen in a heterozygous genotype. ... It has been suggested that this article or section be merged with dominance relationship. ... Marfan syndrome is an autosomal dominant genetic disorder of the connective tissue characterized by disproportionately long limbs, long thin fingers, a typically tall stature, and a predisposition to cardiovascular abnormalities, specifically those affecting the heart valves and aorta. ... It has been suggested that this article or section be merged into Dominance relationship. ...

By aspect of phenotype affected

  • Morphological mutations usually affect the outward appearance of an individual. Mutations can change the height of a plant or change it from smooth to rough seeds.
  • Biochemical mutations result in lesions stopping the enzymatic pathway. Often, morphological mutants are the direct result of a mutation due to the enzymatic pathway.

By inheritance

The human genome contains two copies of each gene- a paternal and a maternal allele.

  • Wildtype or Homozygous non-mutated is when neither allele is mutated.
  • A Heterozygous mutation is when only one allele is mutated.
  • A Homozygous mutation is when both the paternal and maternal alleles have an identical mutation.
  • Compound heterozygous mutations or a Genetic compound is when the paternal and maternal alleles have two different mutations. [3]

Special classes

  • Conditional mutation is a mutation that has wild-type (or less severe) phenotype under certain "permissive" environmental conditions and a mutant phenotype under certain "restrictive" conditions. For example, a temperature-sensitive mutation can cause cell death at high temperature (restrictive condition), but might have no deleterious consequences at a lower temperature (permissive condition).

Causes of mutation

Two classes of mutations are spontaneous mutations (molecular decay) and induced mutations caused by mutagens. 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 number of mutations above the natural background level. ...


Spontaneous mutations on the molecular level include:

  • Tautomerism - A base is changed by the repositioning of a hydrogen atom.
  • Depurination - Loss of a purine base (A or G).
  • Deamination - Changes a normal base to an atypical base; C → U, (which can be corrected by DNA repair mechanisms), or spontaneous deamination of 5-methycytosine (irreparable), or A → HX (hypoxanthine).
  • Transition - A purine changes to another purine, or a pyrimidine to a pyrimidine.
  • Transversion - A purine becomes a pyrimidine, or vice versa.
Benzopyrene, the major mutagen in tobacco smoke, in an adduct to DNA. Produced from PDB 1JDG.
Benzopyrene, the major mutagen in tobacco smoke, in an adduct to DNA. Produced from PDB 1JDG.

Induced mutations on the molecular level can be caused by: Tautomers are organic compounds that are interconvertible by a chemical reaction called tautomerization. ... Depurination is DNA alteration in which the hydrolysis of a purine base (Adenine or Guanine) from the deoxyribose-phosphate backbone occurs. ... Deamination is the removal of an amine group from a molecule. ... Image File history File links Pyrene_adduct. ... Image File history File links Pyrene_adduct. ... Benzo[a]pyrene, C20H12, is a five-ring polycyclic aromatic hydrocarbon that is mutagenic and highly carcinogenic. ... The cigarette is the most common method of smoking tobacco. ...

  • Chemicals
  • Radiation
    • Ultraviolet radiation (nonionizing radiation) excites electrons to a higher energy level. DNA molecules are good absorbers of ultraviolet light, especially that with wavelengths in the 260 to 280 nm range.[citation needed] Two nucleotide bases in DNA - cytosine and thymine-are most vulnerable to excitation that can change base-pairing properties. UV light can induce adjacent thymine bases in a DNA strand to pair with each other, as a bulky dimer.
    • Ionizing radiation

DNA has so-called hotspots, where mutations occur up to 100 times more frequently than the normal mutation rate. A hotspot can be at an unusual base, e.g., 5-methylcytosine. Hydroxylamine is a reactive chemical with formula NH2OH. It can be considered a hybrid of ammonia and water due to parallels it shares with each. ... A base analog is a chemical that can substitute a normal nucleobase in nucleic acids. ... BrdU, also known as 5-bromo-2-deoxyuridine, is a base analog of thymidine, with the thymine substituted by bromouracil. ... For other uses, see acid (disambiguation). ... ENU, also known as N-ethyl-N-nitrosourea (chemical formula C3H6N3O2), is a highly potent mutagen in mice. ... Ethyl methanesulfonate is a mutagenic, teratogenic, and possibly carcinogenic organic compound with formula C3H8O3S and CAS number 62-50-0. ... In chemistry, a hydrocarbon is a cleaning solution consisting only of carbon (C) and hydrogen (H). ... Benzo[a]pyrene, C20H12, is a five-ring polycyclic aromatic hydrocarbon that is mutagenic and highly carcinogenic. ... A colorized automobile engine The internal combustion engine is an engine in which the combustion of fuel and an oxidizer (typically air) occurs in a confined space called a combustion chamber. ... Automobile exhaust Exhaust gas is flue gas which occurs as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel, fuel oil or coal. ... R-phrases , S-phrases , , , , , Flash point > 100 °C Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Absorption spectrum of ethidium bromide Ethidium bromide (sometimes abbreviated as EtBr) is an intercalating agent commonly used as a nucleic... General Name, Symbol, Number platinum, Pt, 78 Chemical series transition metals Group, Period, Block 10, 6, d Appearance grayish white Standard atomic weight 195. ... This article is about the chemical element and its most stable form, or dioxygen. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... For other uses, see Ultraviolet (disambiguation). ... For other uses, see Wavelength (disambiguation). ... A nanometre (American spelling: nanometer, symbol nm) (Greek: νάνος, nanos, dwarf; μετρώ, metrÏŒ, count) is a unit of length in the metric system, equal to one billionth of a metre (or one millionth of a millimetre), which is the current SI base unit of length. ... Radiation hazard symbol. ... In genetics, the mutation rate is the chance of a mutation occurring in an organism or gene in each generation. ... 5-methylcytosine is the methylated form of cytosine. ...


Mutation rates also vary across species. Evolutionary biologists have theorized that higher mutation rates are beneficial in some situations, because they allow organisms to evolve and therefore adapt more quickly to their environments. For example, repeated exposure of bacteria to antibiotics, and selection of resistant mutants, can result in the selection of bacteria that have a much higher mutation rate than the original population (mutator strains). In genetics, the mutation rate is the chance of a mutation occurring in an organism or gene in each generation. ... A mutator genotype is a genotype with an elevated rate of mutation. ...


Nomenclature

Nomenclature of mutations specify the type of mutation and base or amino acid changes.

  • Amino acid substitution - (e.g. D111E) The first letter is the one letter code of the wildtype amino acid, the number is the position of the amino acid from the N terminus and the second letter is the one letter code of the amino acid present in the mutation. If the second letter is 'X', any amino acid may replace the wildtype.
  • Amino acid deletion - (e.g. ΔF508) The Greek symbol Δ or 'delta' indicates a deletion. The letter refers to the amino acid present in the wildtype and the number is the position from the N terminus of the amino acid were it to be present as in the wildtype.

Look up delta in Wiktionary, the free dictionary. ...

Types of mutations

Adaptive mutation

Main article: Adaptive mutation

In mainstream biological thought it is held that while mutagenesis is non-random in many ways, the utility of a genetic mutation to the organism in which it occurs does not affect the rate at which it occurs. However experimental evidence exists that in some instances the rate of specific mutations arising is greater when they are advantageous to the organism than when they are not. In mainstream biological thought it is held that while mutagenesis is non-random in many ways, the utility of a genetic mutation to the organism in which it occurs does not affect the rate at which it occurs. ...


Back mutation

Back mutation is a change in a nucleotide pair of a point-mutated DNA sequence that restores the original sequence and hence the original phenotype.[4] Base pairs, of a DNA molecule. ... A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. ... part of a DNA sequence A DNA sequence (sometimes genetic sequence) is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, The possible letters are A, C, G, and T, representing the four nucleotide subunits of a DNA strand (adenine, cytosine, guanine... Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. ...


Frameshift mutation

Main article: Frameshift mutation

A frameshift mutation is a mutation caused by indels, ie. inserts or deletes a number of nucleotides that is not evenly divisible by three from a DNA sequence. Due to the triplet nature of gene expression by codons, the insertion or deletion can disrupt the reading frame, or the grouping of the codons, resulting in a completely different translation from the original. The earlier in the sequence the deletion or insertion occurs, the more altered the protein produced is. A frameshift mutation (also called a frameshift or a framing error) is a genetic mutation that inserts or deletes a number of nucleotides that is not evenly divisible by three from a DNA sequence. ... One or more bases added to DNA base sequence, alters the framing of codons Category: Science stubs ... A genetic deletion is a genetic aberration in which part of a chromosome is missing. ... A nucleotide is a chemical compound that consists of 3 portions: a heterocyclic base, a sugar, and one or more phosphate groups. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Gene expression, or simply expression, is the process by which the inheritable information which comprises a gene, such as the DNA sequence, is made manifest as a physical and biologically functional gene product, such as protein or RNA. Several steps in the gene expression process may be modulated, including the... RNA codons. ... A genetic deletion is a genetic aberration in which part of a chromosome is missing. ... In biology, a reading frame is a contiguous and non-overlapping set of three-nucleotide codons in DNA or RNA. There are 3 possible reading frames in a strand. ... Translation is the second process of protein biosynthesis (part of the overall process of gene expression). ... One or more bases added to DNA base sequence, alters the framing of codons Category: Science stubs ...


Missense mutation

Main article: Missense mutation

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. Such mutations are responsible for diseases such as Epidermolysis bullosa, sickle-cell disease, and SOD1 mediated ALS(Boillée 2006, p. 39). 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. ... A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. ... This article is about the class of chemicals. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Sickle-cell disease is a blood disorder characterised by red blood cells that assume an abnormal, rigid, sickle shape. ... Structure of the monomeric unit of human superoxide dismutase 2 The enzyme superoxide dismutase (SOD, EC 1. ... Amyotrophic Lateral Sclerosis (ALS, sometimes called Lou Gehrigs Disease, or Maladie de Charcot) is a progressive, usually fatal, neurodegenerative disease caused by the degeneration of motor neurons, the nerve cells in the central nervous system that control voluntary muscle movement. ...


Neutral mutation

Main article: Neutral mutation

A neutral mutation is a mutation that occurs in an amino acid codon (presumably within an mRNA molecule) which results in the use of a different, but chemically similar, amino acid. This is similar to a silent mutation, where a codon mutation may encode the same amino acid (see Wobble Hypothesis); for example, a change from AUU to AUC will still encode leucine, so no discernable change occurs (a silent mutation). In genetics, a neutral mutation is a mutation that occurs in an amino acid codon (presumably within an mRNA molecule) which results in the use of a different, but chemically similar, amino acid. ... RNA codons. ... The interaction of mRNA in a eukaryote cell. ... This article is about the class of chemicals. ... Silent mutations or synonymous mutations are DNA mutations that, although they alter a particular codon, they do not alter the final amino acid, and hence do not affect the final protein. ... Wobble base pairs for inosine Wobble base pairs for Uracil A wobble base pair is a G-U and I-U / I-A / I-C pair fundamental in RNA secondary structure. ... Leucine is one of the 20 most common amino acids and coded for by DNA. It is isomeric with isoleucine. ... Silent mutations or synonymous mutations are DNA mutations that, although they alter a particular codon, they do not alter the final amino acid, and hence do not affect the final protein. ...


Nonsense mutation

Main article: Nonsense mutation

A nonsense mutation is a frameshift 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. In genetics, a nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon (also called a nonsense codon) in the transcribed mRNA, and possibly a truncated (and often nonfunctional) protein product. ... A frameshift mutation (also called a frameshift or a framing error) is a genetic mutation that inserts or deletes a number of nucleotides that is not evenly divisible by three from a DNA sequence. ... part of a DNA sequence A DNA sequence (sometimes genetic sequence) is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, The possible letters are A, C, G, and T, representing the four nucleotide subunits of a DNA strand (adenine, cytosine, guanine... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... RNA codons. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... The interaction of mRNA in a eukaryote cell. ... In mathematics, truncation is the term used for reducing the number of digits right of the decimal point, by discarding the least significant ones. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ...


Point mutation

Main article: Point mutation

A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. Often the term point mutation also includes insertions or deletions of a single base pair (which have more of an adverse effect on the synthesized protein due to nucleotides still being read in triplets, but in different frames- a mutation called a frameshift mutation). A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. ... An illustration of an insertion at chromosome level At DNA level, an insertion means the insertion of a few base pairs into a genetic sequence. ... A frameshift mutation (also called a frameshift or a framing error) is a genetic mutation that inserts or deletes a number of nucleotides that is not evenly divisible by three from a DNA sequence. ...


Silent mutation

Main article: Silent mutation

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. The phrase silent mutation is often used interchangeably with the phrase synonymous mutation; however, synonymous mutations are a subcategory of the former, occurring only within exons. Silent mutations or synonymous mutations are DNA mutations that, although they alter a particular codon, they do not alter the final amino acid, and hence do not affect the final protein. ... The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... This article is about the class of chemicals. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... For other uses, see Gene (disambiguation). ... Diagram of the location of introns and exons within a gene. ... An exon is any region of DNA within a gene, that is transcribed to the final messenger RNA (mRNA) molecule, rather than being spliced out from the transcribed RNA molecule. ... This article is about the class of chemicals. ... DNA strand 1 differs from DNA strand 2 at a single base-pair location (a C/T polymorphism). ...


Harmful mutations

Changes in DNA caused by mutation can cause errors in protein sequence, creating partially or completely non-functional proteins. To function correctly, each cell depends on thousands of proteins to function in the right places at the right times. When a mutation alters a protein that plays a critical role in the body, a medical condition can result. A condition caused by mutations in one or more genes is called a genetic disorder. However, only a small percentage of mutations cause genetic disorders; most have no impact on health. For example, some mutations alter a gene's DNA base sequence but don’t change the function of the protein made by the gene. Studies in the fly Drosophila melanogaster suggest that if a mutation does change a protein, this will probably be harmful, with about 70 percent of these mutations having damaging effects, and the remainder being either neutral or weakly beneficial.[5] A representation of the 3D structure of myoglobin showing coloured alpha helices. ... A genetic disorder is a condition caused by abnormalities in genes or chromosomes. ... Binomial name Meigen, 1830[1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ...


If a mutation is present in a germ cell, it can give rise to offspring that carries the mutation in all of its cells. This is the case in hereditary diseases. On the other hand, a mutation can occur in a somatic cell of an organism. Such mutations will be present in all descendants of this cell, and certain mutations can cause the cell to become malignant, and thus cause cancer[6]. A germ cell is part of the germline and is involved in the reproduction of organisms. ... A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... This article does not cite any references or sources. ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ...


Often, gene mutations that could cause a genetic disorder are repaired by the DNA repair system of the cell. Each cell has a number of pathways through which enzymes recognize and repair mistakes in DNA. Because DNA can be damaged or mutated in many ways, the process of DNA repair is an important way in which the body protects itself from disease. DNA damage resulting in multiple broken chromosomes DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. ...


Beneficial mutations

A very small percentage of all mutations actually have a positive effect. These mutations lead to new versions of proteins that help an organism and its future generations better adapt to changes in their environment. For example, a specific 32 base pair deletion in human CCR5 (CCR5-Δ32) confers HIV resistance to homozygotes and delays AIDS onset in heterozygotes.[7] The CCR5 mutation is more common in those of European descent. One theory for the etiology of the relatively high frequency of CCR5-Δ32 in the European population is that it conferred resistance to the bubonic plague in mid-14th century Europe. People who had this mutation were able to survive infection; thus, its frequency in the population increased.[8] It could also explain why this mutation is not found in Africa where the bubonic plague never reached. Newer theory says the selective pressure on the CCR5 Delta 32 mutation has been caused by smallpox instead of the bubonic plague.[9] Base pairs, of a DNA molecule. ... CCR5, short for chemokine (C-C motif) receptor 5, is a chemokine receptor. ... CCR5, short for chemokine (C-C motif) receptor 5, is a chemokine receptor. ... Species Human immunodeficiency virus 1 Human immunodeficiency virus 2 Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS, a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections). ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... For other uses, see AIDS (disambiguation). ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... This article is about the medical term. ... The bubonic plague or bubonic fever is the best-known variant of the deadly infectious disease caused by the enterobacteria Yersinia pestis (Pasteurella pestis). ... This 14th-century statue from south India depicts the gods Shiva (on the left) and Uma (on the right). ... This page is a candidate for speedy deletion. ... Smallpox (also known by the Latin names Variola or Variola vera) is a contagious disease unique to humans. ...


See also

Aneuploidy is a change in the number of chromosomes that can lead to a chromosomal disorder. ... Space-filling model of the antioxidant metabolite glutathione. ... Melopsittacus undulatus at Chai-Negev, Revivim, Israel. ... A homeobox is a DNA sequence found within genes that are involved in the regulation of development (morphogenesis) of animals, fungi and plants. ... Most biologists believe that adaptation occurs through the accumulation of small changes, such as the slight differences between parents and their children, some of which can result from mutations. ... 1946 Nobel Prize winner Hermann J. Muller (1890-1967) coined the terms amorph, hypomorph, hypermorph, antimorph and neomorph to classify mutations based on their behaviour in various genetic situations. ... This article is about biological mutants. ... Polyploidy refers to cells or organisms that contain more than two copies of each of their chromosomes. ... Robertsonian translocation is a common form of chromosomal rearrangement that occurs in the five acrocentric human chromosome pairs, namely 13, 14, 15, 21, and 22. ... Often abbreviated to STM, Signature-Tagged Mutagenesis is a genetic technique used to study gene function. ... Site-directed mutagenesis is a molecular biology technique in which a mutation is created at a defined site in a DNA molecule, usually a circular molecule known as a plasmid. ...

References

  1. ^ Freese, Ernst (1959). "The Difference between Spontaneous and Base-Analogue Induced Mutations of Phage T4". Proc of NAS 45 (4): 622-633.  [1]
  2. ^ Freese, Ernst (1959). "The Specific Mutagenic Effect of Base Analogues on Phage T4". J. Mol. Biol. 1: 87-105. 
  3. ^ Medterms.com [2]
  4. ^ Ellis NA, Ciocci S, German J (2001). "Back mutation can produce phenotype reversion in Bloom syndrome somatic cells". Hum Genet 108 (2): 167-73.  PMID 11281456
  5. ^ Sawyer SA, Parsch J, Zhang Z, Hartl DL (2007). "Prevalence of positive selection among nearly neutral amino acid replacements in Drosophila". Proc. Natl. Acad. Sci. U.S.A. 104 (16): 6504-10. PMID 17409186. 
  6. ^ Ionov Y, Peinado MA, Malkhosyan S, Shibata D, Perucho M (1993). "Ubiquitous somatic mutations in simple repeated sequences reveal a new mechanism for colonic carcinogenesis". Nature 363 (6429): 558-61. PMID 8505985. 
  7. ^ CCR5 receptor gene and HIV infection, Antonio Pacheco..
  8. ^ PBS:Secrets of the Dead. Case File: Mystery of the Black Death.
  9. ^ Galvani A, Slatkin M (2003). "Evaluating plague and smallpox as historical selective pressures for the CCR5-Δ32 HIV-resistance allele". Proc Natl Acad Sci U S A 100 (25): 15276-9. PMID 14645720. 
  • Leroi A. 2003. Mutants: On the form, varieties & errors of the human body. 1:16-17. Harper Collins 2003
  • Maki H. 2002. Origins of spontaneous mutations: specificity and directionality of base-substitution, frameshift, and sequence-substitution mutageneses. Annual Review of Genetics 36:279-303.
  • Taggart R. Starr C. Biology The Unity and Diversity of Life: Mutated Genes and Their Protein Products. 14.4:227. Thompson Brooks/Cole 2006.

Online books

  • Chapter 7, The Molecular Basis of Mutation in Modern Genetic Analysis by Anthony J. F. Griffiths, William M. Gelbart, Jeffrey H. Miller and Richard C. Lewontin (1999) published by W. H. Freeman and Company ISBN 0-7167-3597-0.
  • Chapter 9, Instability of the human genome: mutation and DNA repair in Human Molecular Genetics 2 by Tom Strachan and Andrew P. Read (1999) published by John Wiley & Sons, Inc.
  • Genes and Disease from the National Library of Medicine provides descriptions of mutations that cause human diseases. For example, a common mutation associated with Huntington disease is an increased number of copies of repeated CGA triplets in the Huntingtin gene.
  • GeneReviews by Roberta A. Pagon, Editor-in-chief is made available by the University of Washington and contains peer-reviewed descriptions of heritable diseases written by experts. For example, BRCA1 and BRCA2 Hereditary Breast/Ovarian Cancer describes mutations in BRCA1 and BRCA2 that are associated with predispositions to cancer.

Richard Lewontin Richard Charles Dick Lewontin (born March 29, 1929) is an American evolutionary biologist, geneticist and social commentator. ... The U.S. National Library of Medicine (NLM), operated by the U.S. federal government, is the worlds largest medical research library. ... Huntingtin is a protein, present in human cells. ... The University of Washington, founded in 1861, is a public research university in Seattle, Washington. ... BRCA1 (breast cancer 1, early onset) is a human gene that belongs to a class of genes known as tumor suppressors, which regulate the cell cycle and prevent uncontrolled proliferation. ... BRCA2 refers to either a gene (BReast-CAncer susceptibility gene 2, located on human chromosome 13, 13q12-13) or the protein coded for by that gene. ...

External links

While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection. ... For other uses, see Adaptation (disambiguation). ... Macroevolution refers to evolution that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population. ... Microevolution is the occurrence of small-scale changes in allele frequencies in a population, over a few generations, also known as change at or below the species level. ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ... For other uses, see Natural selection (disambiguation). ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... In population genetics, gene flow (also known as gene migration) is the transfer of alleles of genes from one population to another. ... Evolutionary developmental biology (evolution of development or informally, evo-devo) is a field of biology that compares the developmental processes of different animals in an attempt to determine the ancestral relationship between organisms and how developmental processes evolved. ... We dont have an article called Phenotypic plasticity Start this article Search for Phenotypic plasticity in. ... Norms of reaction for two genotypes. ... Many organisms consist of modules, both anatomically and in their metabolism. ... A number of different Markov models of DNA sequence evolution have been proposed. ... The evolution of sex is a major puzzle in modern evolutionary biology. ... Enquiry into the evolution of ageing aims to explain why almost all living things weaken and die with age. ... The nature and origins of hominid intelligence is a much-studied and much-debated topic, of natural interest to humans as the most successful and intelligent hominid species. ... Diagram of major stages in the eyes evolution. ... Plant evolution is an aspect of the study of biological evolution, involving predominantly the evolution of plants suited to live on land, the greening of the various land masses by the filling of their niches with land plants, and the diversification of the groups of land plants. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... For the history of humans on Earth, see History of the world. ... Anagenesis is the progressive evolution of species involving a change in gene frequency in an entire population rather than a cladogenetic branching event. ... Catagenesis is an archaic term from evolutionary biology referring to evolutionary directions that were considered retrogressive. ... Cladogenesis is an evolutionary splitting event in which each branch and its smaller branches is a clade; an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of animals or plants. ... Evolutionary thought has roots in antiquity as philosophical ideas conceived during the Ancient Greek and Roman eras, but until the 18th century, biological thought was dominated by essentialism, the idea that living forms are static and unchanging in time. ... For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... The 1859 edition of On the Origin of Species First published in 1859, The Origin of Species (full title On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life) by British naturalist Charles Darwin is one of the pivotal... The modern evolutionary synthesis refers to a set of ideas from several biological specialities that were brought together to form a unified theory of evolution accepted by the great majority of working biologists. ... The gene-centered view of evolution, gene selection theory or selfish gene theory holds that natural selection acts through differential survival of competing genes, increasing the frequency of those alleles whose phenotypic effects successfully promote their own propagation. ... This article is about life in general. ... Ecological genetics is the study of genetics (itself a field of biology) from an ecological perspective. ... Molecular evolution is the process of the genetic material in populations of organisms changing over time. ... Phylogenetic groups, or taxa, can be monophyletic, paraphyletic, or polyphyletic. ... Biological systematics is the study of the diversity of life on the planet earth, both past and present, and the relationships among living things through time. ... This is a list of topics in evolutionary biology and evolution. ... Life on Earth  â€¢  â€¢  | Axis scale: millions of years ago. ...

  Results from FactBites:
 
Mutation - Wikipedia, the free encyclopedia (1754 words)
Mutations can be caused by copying errors in the genetic material during cell division and by exposure to radiation, chemicals, or viruses, or can occur deliberately under cellular control during the processes such as meiosis or hypermutation.
Mutations are considered the driving force of evolution, where less favorable (or deleterious) mutations are removed from the gene pool by natural selection, while more favorable (beneficial or advantageous) ones tend to accumulate.
For example, a common mutation associated with Huntington disease is an increased number of copies of repeated CGA triplets in the Huntingtin gene.
Mutation - definition of Mutation in Encyclopedia (644 words)
In multicellular organisms, mutations can be subdivided into germline mutations, which can be passed on to progeny and somatic mutations, which (when accidental) often lead to the malfunction or death of a cell and can cause cancer.
Mutations are considered the driving force of evolution, where less favorable (or deleterious) mutations are removed from the gene pool by natural selection, while more favorable (or beneficial) ones tend to accumulate.
Neutral mutations do not affect the organism's chances of survival in its natural environment and can accumulate over time, which might result in what is known as punctuated equilibrium; the modern interpretation of classic evolutionary theory.
  More results at FactBites »

 
 

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