mutation

Virus evolution

...es , in particular RNA viruses , have fairly high mutation rates (on the order of one point mutation or more per genome per round of replication in RNA viruses) and short generation times. As a consequ...

Twin

... are genetically identical unless there has been a mutation in development; they are only usually , but not necessarily , the same gender. They look alike, except that they are sometimes mirror images, but examination of details such as fingerprints can tell them apart. As they mature, identical twins oft...

Tumor

...e mechanisms can also eventually lead to cancer. A mutation in one oncogen or one tumor repressor gen is usually not enough for a tumor to occur. A combination of a number of mutations is necessary. DNA microarrays can be used to determine if oncogens or tumor repressor gens have been mutated. Possibly in...

Species

...al stepping stone to the modern theory of adaptive mutation . Lamarck's long-discarded ideas of the goal-oriented evolution of species, also known the teleological process, have also received renewed attention, particularly by proponents of artificial selection . Charles Darwin and Alfred Wallace provid...

Speciation

...s changes from sexual reproduction and/or random mutation (in addition to any other various contributors to genetic change) until the populations are no longer capable of interbreeding ( cladogenesis ). (This is one definition of what a species is; see species .) If a single population of a species change...

RNA virus

...ne RNA replication: All RNA viruses have very high mutation rates because they lack DNA polymerases which ca...ut mistakes. DNA viruses have considerably lower mutation rates. See also retroviruses . Although RNA usually mutates rapidly, recent work found that the ...

Red Queen

...is is for two reasons. First, if an advantageous mutation occurs in an asexual line, it is impossible for that mutation to spread without wiping out all other lines, which may have different advantageous mutations of the...

Promoter

...nt of promoter malfunction, either through direct mutation of a promoter sequence or mutation in a transcription factor or transcriptional co-activator . Keep in mind that most diseases are h...

Prion

...s of effort, Cox could not identify a conventional mutation that was responsible for the [PSI+] trait. In 1994 , yeast geneticist Reed Wickner correctly hypothesized that [PSI+] as well as another mysterious heritable trait, [URE3], resulted from prion forms of certain normal cellular proteins. It was soon ...

Population genetics

...ary forces: natural selection , genetic drift , mutation and migration . It also takes account of population subdivision and population structure in space. As such, it is the theory that attempts to explain such phenomena as adaptation and speciation .Population genetics was a vital ingredient in the ...

Polymerase chain reaction

...tagenesis allows the experimenter to introduce a mutation at a specific location on the DNA strand. Usually, the desired mutation is incorporated in the primers used for the PCR program. Random mutagenesis, on the other hand, is...

Oncogene

...ction. There are two basic activation types: A mutation within a protooncogene can cause a change in the protein structure, caused by an increase in protein ( enzyme )activity a loss of regulation the creation of a hybrid protein , through a chromosomal aberration during cell division . A disti...

Neutral theory of molecular evolution

...w allele arises typically through the spontaneous mutation of a single nucleotide within the sequence of a g... the genesis of an embryo and offspring does the mutation contribute a new allele to the population. Neutral substitutions create new neutral alleles. Throug...

Natural selection

...se of both asexual and sexual reproduction, random mutation (including DNA transcription errors); in the case of sexual reproduction (which mixes the DNA of two parents into an offspring), gene flow and genetic drift are also important mechanisms. Competition (typically among males to impregnate fema...

Muller's ratchet

...sm). Muller's ratchet applies to any deleterious mutation that occurs in a vertically transmitted organism. It may be that the mutation is deleterious, but not lethal. Furthermore, the organism with the mutation may have another advant...

Antibiotic resistance

...ntibiotic .Antibiotic resistance develops through mutation or plasmid exchange between bacteria of the s...nvironmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspri...

Morphogenesis

...ox genes like bicoid . An example of a homeotic mutation is the so-called antennapedia mutation. In Drosophila , antennae and legs are created by the same basic "program", they only differ in a single transcription factor. If this transcription factor is damaged, the fly grows legs on its head instead of ...

Modern evolutionary synthesis

...variation in populations arises by chance through mutation (this is now known to be due to mistakes in DNA replication ) and recombination (crossing over of homologous chromosomes during meiosis ). Evolution consists primarily of changes in the frequencies of alleles between one generation and an...

Molecular evolution

...were a large enough number of alleles so that any mutation would lead to a different allele (that is the probability of back mutation to the original allele would be low enough to be negligible); and second, that the mutations would r...

Mitochondrion

...ammonia , a waste product of protein metabolism. A mutation in the genes regulating any of these functions can result in a variety of mitochondrial diseases . Energy conversion As stated above, the primary function of the mitochondria is the production of ATP . This is done by metabolizing the major pro...

Mitochondrion

...ammonia , a waste product of protein metabolism. A mutation in the genes regulating any of these functions can result in a variety of mitochondrial diseases . Energy conversion As stated above, the primary function of the mitochondria is the production of ATP . This is done by metabolizing the major pro...

Microevolution

...l. These changes may be due to several processes: mutation , gene flow , genetic drift , as well as natural selection . Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Biologists distinguish between microevolution an...

Max Delbr

...sistance to virus infection is caused by random mutation and not adaptive change. For that, they were awarded the Nobel Prize in Physiology or Medicine in 1969 , sharing it with Alfred Hershey . From the 1950s on, Delbrck worked on physiology rather than genetics. He also set up the institute for...

Marfan syndrome

...penetrance, therefore not all persons carrying the mutation develop the disease. Without the structural support provided by fibrillin, many connective tissues are weakened, which can have severe consequences on support and stability. A related disease has been found in mice , and it is hoped that the study o...

Malaria

...st malaria because of their particular hemoglobin mutation ; this explains why sickle cell anemia is particularly common among people of African origin. There is a theory that another hemoglobin mutation, which causes the genetic disease thalassemia , may also give its carriers an enhanced immunity to malar...

Lysozyme

...some forms of hereditary amyloid , the cause is a mutation in the lysozyme gene, which leads to accumulated lysozyme in several tissues (). History Alexander Fleming (1881-1955), who discovered penicillin , described lysozyme in 1922 (Fleming A. On a remarkable bacteriolytic element found in tissue...

Lipase

...ncy: a new patient homozygote for the preponderant mutation Gly188Glu in the human LPL gene and review of reported mutations: 75 % are clustered in exons 5 and 6. Ann Genet. 44(1):25-32. Girod, A., C. E. Wobus, Z. Zadori, M. Ried, K. Leike, P. Tijssen, J. A. Kleinschmidt, and M. Hallek. 2002. The VP1 capsid ...

Isozyme

...ing sequence of the gene . As with any other new mutation , there are three things that may happen to a new ...example a long way from the active site then the mutation may be selectively neutral and subject to genetic drift . (3) In rare cases the mutation may resu...

Hardy-Weinberg principle

...diploid and experience: no selection no mutation no migration ( gene flow ) Causes of deviation When the Hardy–Weinberg assumptions are not met this can cause deviations from expectation , but depending which assumption is not met, such deviations may or may not be statistically ...

Genetics

...ary forces: natural selection , genetic drift , mutation and migration . It is the theory that attempts to explain such phenomena as adaptation and speciation . The related subfield of quantitative genetics, which builds on population genetics, aims to predict the response to selection given data o...

Genetic code

...riginally the names of the specific genes in which mutation of each of these stop codons was first detected. ...mple, four-fold degenerate codons can tolerate any mutation at the third position; two-fold degenerate codons can tolerate one out of the three possible mutatio...

Genetic drift

...ange by the introduction of a new allele by a new mutation . The lifetime of an allele is governed by the effective population size. In a very small population, only a few generations might be required for genetic drift to result in fixation. In a large population, it would take many more generations. On av...

Gene

...sely, a biologist might refer to an allele or a mutation that has been implicated in or is associated w...rise. Once propagated to the next generation, this mutation may lead to variations within a species' population. Variants of a single gene are known as alleles...

Fitness landscape

...reached (Fig. 1). There it remains, unless a rare mutation opens a path to a new, higher fitness peak. Note, however, that at high mutation rates this picture is somewhat simplistic. A population may not be able to climb a very sharp peak i...

Extinction

...owever, it is sometimes possible for a deleterious mutation to be spread throughout a population through the effect of genetic drift . A diverse or "deep" gene pool gives a population a higher chance of surviving an adverse change in conditions. Effects that cause or reward a loss in genetic diversity ...

Ewens's sampling formula

...he population is in statistical equilibrium under mutation and genetic drift and the role of selection at the locus in question is negligible, and (3) every mutant allele is novel. This is a probability distribution on the set of all partitions of the integer n . Among probabilists and statistician...

Evolution

...individuals and subject to a process of change or mutation (described below). However, other non-DNA based ...utation. Differential survival of traits While mutation can create new alleles , other factors influence the frequency of existing alleles. These factors m...

Bacterium

...vidual cells through recombinant events such as mutation (random genetic change within a cell's own genetic code).Similar to more complex organisms, bacteria also have mechanisms for exchanging genetic material. Although not equivalent to sexual reproduction, the end result is that a bacterium contains a ...

Enzyme

... correct function, and because the frequency of a mutation which would produce a nonfunctional active region...ns by long stretches of 'spacer' amino acids where mutation is much less critical (although some mutations in these regions can also inactivate the product). Th...

Morphogenesis

...ox genes like bicoid . An example of a homeotic mutation is the so-called antennapedia mutation. In Drosophila , antennae and legs are created by the same basic "program", they only differ in a single transcription factor. If this transcription factor is damaged, the fly grows legs on its head instead of ...

Escherichia coli

...l the time from the natural biological process of mutation , and some of those strains have characteristics that can be harmful to a host animal. Although in most healthy adult humans such a strain would probably cause no more than a bout of diarrhea , and might produce no symptom at all, in young children...

DNA

...up as a complete replica of the original, unless a mutation occurs; Mutations are simply chemical imperfec...ation can result in a less than perfect copy (see mutation ), and each of them consists of one original and one newly synthesized strand. This is called semi...

Diabetes mellitus

...r. A small proportion of type 1 diabetics carry a mutation that causes maturity onset diabetes of the young (MODY). There is an even stronger inheritance pattern for Type 2 diabetes; those with type 2 ancestors or relatives have very much higher chances of developing Type 2. It is also often connected to...

Genetic code

...riginally the names of the specific genes in which mutation of each of these stop codons was first detected. ...mple, four-fold degenerate codons can tolerate any mutation at the third position; two-fold degenerate codons can tolerate one out of the three possible mutatio...

Cancer

...he Philadelphia chromosome , is a special type of mutation and may involve oncogenes or tumor suppressor gene...tations in both types of genes are necessary, as a mutation limited to an oncogene would be suppressed by normal mitosis control. Mutations can have various ca...

Bacterium

...vidual cells through recombinant events such as mutation (random genetic change within a cell's own genetic code).Similar to more complex organisms, bacteria also have mechanisms for exchanging genetic material. Although not equivalent to sexual reproduction, the end result is that a bacterium contains a ...

Apoptosis

...pability of apoptosis is damaged (for example, by mutation ), or if the initiation of apoptosis is blocked (by a virus), a damaged cell can continue dividing without restrictions, developing into cancer . For example, as part of the hijacking of the cell's genetic system carried out by human papillomavirus...

Antigenic shift

...sted with antigenic drift which is the natural mutation over time of known strains of influenza (or other things, in a more general sense) to evade the immune system. Antigenic drift occurs in all types of influenza including influenza A, B and C. Antigenic shift, however, occurs only in influenza A beca...

Antibiotic resistance

...ntibiotic .Antibiotic resistance develops through mutation or plasmid exchange between bacteria of the s...nvironmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspri...

Ames test

...etically modified such that only a certain type of mutation (i.e. a base pair mutation or a frameshift mutation) will cause the strand to revert to a normal state, not requiring nutrients...

Alternative splicing

...regulation are inherited, the interpretation of a mutation may be changed. It has been proposed that for eukaryotes it was a very important step towards higher efficiency, because information can be stored much more economically. Several proteins can be encoded in a DNA sequence whose length would only ...

Allele frequency

... selection, these forces include genetic drift , mutation and migration . Compare genotype frequency . Example If there are ten individuals in a population and at a given locus there are two possible alleles, A and a , then if the genotypes of the individuals are: AA , Aa , AA , aa , Aa ...

Adaptive radiation

...hes . This is an evolutionary process driven by mutation and natural selection . Adaptive radiation often occurs when a species is introduced to a new ecosystem , or when a species can survive in an environment that was unreachable before. For example, the Darwin's finches on the Galapagos islands...