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 Huntingtingene.
en.wikipedia.org /wiki/Mutation (1754 words)
Mutation Info - Encyclopedia WikiWhat.com(Site not responding. Last check: 2007-10-22)
Mutations (or mutagenesis, both words originating in the Latin word mutare, to change) are permanent, transmissible changes to the genetic material (usually DNA or RNA) of an organism.
Mutations are considered the driving force of evolution, where less favorable mutations are removed by natural selection, but favorable ones tend to accumulate.
Sometimes the word mutation is used broadly to include variations resulting from aberrations of chromosomes; in chromosomalmutations the number of chromosomes may be altered, or segments of chromosomes may be lost or rearranged.
For example, the inherited sickle cell disease is the result of a mutation that results in the substitution of the amino acid valine for glutamic acid in hemoglobin.
Mutations may be induced by exposure to ultraviolet rays and alpha, beta, gamma, and X radiation, by extreme changes in temperature, and by certain mutagenic chemicals such as nitrous acid, nitrogen mustard, and chemical substitutes for portions of the nucleotide subunits of genes.
Though it is not practical to eliminate all deleterious mutation, the incidence of affected individuals may be significantly reduced through a combination of intelligent breeding practice and the development of DNA tests.
Mutations are changes in an organism's DNA that potentially affect the correct functioning of genes.
This mutation eliminates 85-90% of the active clotting factor, but this low level is still sufficient to protect a homozygous affected individual from excessive bleeding in most situations.
The mutation could be a change in one allele to resemble one currently in the population, for example from a dominant to a recessiveallele.
If the mutation is beneficial to the species as a whole, migration from the population in which it initially arose must occur for it to spread to other populations of the species.
A natural result of mutation is that new forms develop, and these new forms may or may not add to the fitness of the individual.
Mutation - EvoWiki(Site not responding. Last check: 2007-10-22)
Mutation is the ultimate source of variation on which natural selection acts.
This held that mutations in the gene were what was selected for by natural selection, which allowed for new variation to be constantly added to a population.
Mutations can have a wide variety of effects depending on the function of the DNA in which they occur.
Mutation, missense: A genetic change involving the substitution of one base in the DNA for another which results in the substitution of one amino acid in a polypeptide for another.
This is in contrast to a nonsensemutation which has no meaning except to halt the reading of the genetic message.
The first missensemutation discovered in humans was found to be responsible for sickle hemoglobin, the molecular basis of sickle cell trait and sickle cell anemia.
These mutations, in contrast to the somaticmutations, will be passed on to the next generation, because they occur in the cells that produce the next generation.
A mutation may occur in a gene that encodes an enzyme involved in a metabolic pathway, such as an enzyme involved in the biosynthesis of an amino acid.
Some mutations are lethal to an organism, like the yellow coat color allele in mice (as outlined in the module on extensions of Mendelism) or the Huntington's allele of humans.
How Genetic Disorders Occur - myDNA(Site not responding. Last check: 2007-10-22)
Mutations range in size from one DNA base to a large segment of a chromosome.
Mutations that are passed from parent to child are called hereditary mutations or germlinemutations (because they are present in the egg and sperm cells, which are also called germ cells).
This type of mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene.
Mutation(Site not responding. Last check: 2007-10-22)
Mutations are also found at the center of a number of diseases and disease processes.
Indeed, mutations are the only source of novel variation within wild populations, and it is upon this variation that natural selection acts (i.e., evolution).
To mutagenize (a.k.a., mutate) is to treat an organism with chemicals (mutagens) that cause an increase in the rate of mutation.
Mutation(Site not responding. Last check: 2007-10-22)
The effect of mutation is to reintroduce divergence into a converging population.
The biological inspiration behind this operator is the way in which a chance mutation in a natural chromosome can lead to the development of desirable traits which give the individual displaying these characteristics an advantage over its competitors [Parker, 1992].
Following the reproduction, crossover and mutation, we see that of the initial population, strings 1 and 2 were selected ones (average fitness), string 3 was not selected (low fitness) and string 4 was selected twice (high fitness).
These problems with mutation rates do not seem to be appreciated by most biologists, and even the creationist sources I have read do not seem to comprehend the seriousness of the problems posed for the theory of evolution by the rates of mutation observed and assumed for evolution.
A mutation to the functional DNA will change the amino acid more than 2/3 of the time, and if it does, the mutation will be harmful about 9/10 of the time or more (according to estimates by biologists).
Assuming a mutation per base pair every 200 million years (4.61 per billion years), this means 150 million point mutations in the functional DNA and at least 100 million harmful mutations every 200 million years, since 2/3 of the mutations are harmful.
Recessivemutations (most of them are) will not be seen except on the rare occasions that both parents contribute a mutation at the same locus to their child.
The frequency with which a given mutation is seen in a population (e.g., the mutation that causes cystic fibrosis) provides only a rough approximation of mutation rate — the rate at which fresh mutations occur — because of historical factors at work such as
The significance of mutations is profoundly influenced by the distinction between germline and soma.
Females of the blue mutation are similar to the male, but lack the cobalt blue rump and wings.
Both the Yellow and Blue mutations are simple recessive, it requires a copy of the same recessivegene from each parent in order for the trait to be expressed in the offspring (visual).
This is believed to be the first mutation of Green Rumped Parrotlets to occur in the US and, like the Pacifics, also appears to be a recessivemutation.
In this description, a mutation is the change in the DNA sequence (the genotype) which causes that altered phenotype.
I would like to propose instead the following definition: a mutation is a change in the sequence of DNA from what is found in the wild type irrespective of the resulting phenotype.
Occasionally reference will be made to conditional lethal mutations where the strain carrying such a mutation dies under the non-permissive conditions regardless of the medium.
The discovery of the factor V mutation in 1994 has revolutionized the diagnostic work-up of patients with hypercoagulability, and the ability to detect this mutation in asymptomatic relatives offers the opportunity to prevent venous thrombosis through special management of those at risk.
This mutation is a single G to A base change that results in replacement of an arginine with a glutamine in the protein, destroying a cleavage site and thereby limiting factor V degradation by APC.
The factor V mutation test is accurate regardless of the clinical condition or medication of the patient.
www.mostgene.org /gd/gdvol14b.htm (1355 words)
Mutation Detection 2005-Santorini(Site not responding. Last check: 2007-10-22)
The Mutation Detection Symposium this year will be held in the Petros M. Nomikos Conference Centre which is located in the capital of the island of Santorini which is generally considered to be one of the most beautiful places in the world.
Mutation Detection is a highly specialized field and these workshops gather inventors & major users of mutation detection techniques to discuss new technologies, improvements of old techniques & their application as well as inherent problems in the techniques.
In the case of single gene disorders scanning for causative mutations will become more important than ever as an increasing number of diseasegenes are discovered and as this strategy is used in more and more laboratories in advanced and less advanced countries.
Mutation(Site not responding. Last check: 2007-10-22)
Induced mutation (def) is caused by mutagens, substances that cause a much higher rate of mutation.
Substitution of one nucleotide for another is a result of tautomeric shift, a rare process by which the hydrogen atoms of a deoxyribonucleotide base move in a way that changes the properties of its hydrogen bonding.
This is sometimes seen with a single substitution mutation when the change in the DNA base sequence results in a new codon still coding for the same amino acid (see Fig.
This segment tells the story of a genetic mutation affecting the population of West Africa.
Although helpful in preventing malaria, this mutation can also lead to sickle cell anemia.
The sickle cell mutation is a like a typographical error in the DNA code of the gene that tells the body how to make a form of hemoglobin (Hb), the oxygen-carrying molecule in our blood.
This is redundant with the term "heritable" but points out an important genetic issue: The mutations which are of primary concern are those in the germ line as these are the one that will be passed on.
There are measurable mutation rates and that there can be a genetic variation for mutation rates; "mutator strains" of bacteria exist.
Mutations in the replication or repair machinery of DNA can alter mutation rates.