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Mutations in Biological Definition

Cancer

... to ensure the integrity of organs and tissues . mutations in DNA that lead to cancer appear to disrupt ... of genes . Typically, a series of several mutations is required before a cell becomes a cancer cell. ... oncogenes or tumor suppressor genes. In general, mutations in both types of genes are necessary, as a ...

Genetic code

... is what accounts for the existence of silent mutations . These properties of the genetic code make it ... codons can tolerate one out of the three possible mutations at the third position. Since transition mutations (purine to purine or pyrimidine to pyrimidine ...

DNA

... 8 Single-stranded DNA (ssDNA) and repair of mutations 9 The history of DNA research 9.1 ... of the original, unless a mutation occurs; mutations are simply chemical imperfections in this ... chain is trimmed, or added to; all other basic mutations can be described as combinations of these ...

Evolution

... pinned much of this variation onto mutations. mutations are permanent, transmissible changes to the ... or hypermutation . 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 ...

Gene

... gene 2.2 Expression of molecular genes 2.3 mutations and evolution 3 History 4 See also ... spontaneous errors (e.g. in DNA replication ) mutations in the sequence of a gene may arise. Once ... more "material entity" than the first one. mutations and evolution Just as there are many factors ...

Genetic code

... is what accounts for the existence of silent mutations . These properties of the genetic code make it ... codons can tolerate one out of the three possible mutations at the third position. Since transition mutations (purine to purine or pyrimidine to pyrimidine ...

Homeobox

... will grow in a developing fetus or larva . mutations in any one of these genes can lead to the growth ... morphogenesis are the same for many organisms. mutations to homeobox genes can produce easily visible phenotypic changes. Two examples of homeobox mutations in the above-mentioned fruit fly are legs where ...

Isozyme

... is likely that one or the other will be lost as mutations accumulate, resulting in a pseudogene . However, if the mutations do not immediately prevent the enzyme from ... tissues. Allozymes may result from point mutations or from insertion-deletion ( indel ) events that ...

Lipase

... three human genetic diseases are caused by mutations in lipase genes. Lipoprotein Lipase Deficiency is caused by mutations in the gene encoding lipoprotein lipase [2] ... (CESD) and Wolman Disease are both caused by mutations in the gene encoding lysosomal lipase, also ...

Molecular evolution

... 2 Principles of molecular evolution 2.1 mutations 2.2 Causes of change in allele frequency ... RNA. Principles of molecular evolution mutations Main article: Mutation mutations are permanent, transmissible changes to the ...

Polymerase chain reaction

... of ancient DNA 4.7 Genotyping of specific mutations 4.8 Comparison of gene expression 5 ... makes mistakes when copying DNA, leading to mutations (errors) in the DNA sequence, since it lacks ... and can significantly reduce the number of mutations that occur in the copied DNA sequence. ...

Tumor

... benign if it does not. Tumors are caused by mutations in DNA of cells . An accumulation of mutations is needed for a tumor to emerge. mutations that activate oncogenes or repress tumor ...

Digital organism

... core world programs were written was very brittle, and more often than not mutations would completely destroy the functionality of a program. The first to ... However, Ray made some key changes to the programming language such that mutations were much less likely to destroy a program. With these modifications, he ...

Experimental evolution

... With modern microbiological tools, it is possible to pinpoint the mutations that selection acts upon and what brought about the adaptations and to find out how exactly these mutations work. Because of the large number of generation required for adaptation ...

Gene duplication

... biology is that if a gene is under natural selection , most mutations will lead to the death of the organism. When a gene is duplicated ... discover new functions. Alternatively, the gene may acquire deleterious mutations and become a pseudogene . The postulate that gene duplication has a ...

Promoter

... is a major resource for gathering information on the relationship between mutations and natural variation in gene sequence and susceptibility to hundreds of ... RH, Peters DJ, et al. (1995). Rubinstein-Taybi syndrome caused by mutations in the transcriptional co-activator CBP . Nature . 376 (6538), ....

X chromosome

... 25,000 total genes in the human genome. Genetic disorders that are due to mutations in genes on the X chromosome are described as X linked . The X ... in the chromosomes. Other conditions Many diseases are due to mutations on the X chromosome. These are characteristic as they occur much more ...

Bioinformatics

... are used to find similar sequences in the genome of dozens of organisms, within billions of nucleotides . These programs can compensate for mutations (exchanged, deleted or inserted bases) in the DNA sequence, in order to identify sequences that are related, but not identical. A variant of this ...

Bioinformatics

... are used to find similar sequences in the genome of dozens of organisms, within billions of nucleotides . These programs can compensate for mutations (exchanged, deleted or inserted bases) in the DNA sequence, in order to identify sequences that are related, but not identical. A variant of this ...

Ploidy

... 21 (the cause of Down syndrome ) are relatively common. Many forms of cancer have incorrect ploidy numbers, due to the accumulation of mutations which increase chromosome missegregation . Polyploidy Polyploidy is the state where all cells have multiple pairs of chromosomes beyond the ...

Enzyme

... conserved against mutation, separating these regions by long stretches of 'spacer' amino acids where mutation is much less critical (although some mutations in these regions can also inactivate the product). This has the additional effect of making each region act, relative to mutation, somewhat like an ...

Exon

... that exploits the existence of the intron-exon architecture to find new genes . Exonization is the creation of a new exon, as result of mutations in intronic sequences. Splicing can be experimentally modified so that targeted exons are excluded from mature mRNA transcripts by blocking the ...

Genetics

... - the modern synthesis starts. 1913 Gene maps show chromosomes containing linear arranged genes 1927 Physical changes in genes are called mutations 1928 Frederick Griffith discovers a hereditary molecule that is transmissible between bacteria (see Griffiths experiment ) 1931 Crossing ...

Ploidy

... 21 (the cause of Down syndrome ) are relatively common. Many forms of cancer have incorrect ploidy numbers, due to the accumulation of mutations which increase chromosome missegregation . Polyploidy Polyploidy is the state where all cells have multiple pairs of chromosomes beyond the ...

Histone

... with histones during interphase . It also appears that the structure of histones have been evolutionarily conserved, as any deleterious mutations would be severely maladaptive. History Histones were discovered in 1884 by Albrecht Kossel . The word "histone" dates from the late 19th ...

Marfan syndrome

... made solely on clinical findings. Most individuals with Marfan syndrome have another affected family member, but about 30% of cases are due to new mutations and they are the first in their family. Genetic counseling is available for families who may be at risk for Marfan syndrome. Estimates indicate ...

Microbiology

... of liquid culture. These traits allowed Joshua and Esther Lederberg to devise an elegant experiment in 1951 demonstrating that adaptive mutations arise from preadaptation rather than directed mutation. For this purpose, they invented replica plating , which allowed them to transfer numerous ...

Molecular genetics

... genetics One of the first tools available to molecular geneticists is the forward genetic screen . The aim of this technique is to identify mutations that produce a certain phenotype . A mutagen is very often used to accelerate this process. Once mutants have been isolated, the mutated gene ...

Muller's ratchet

... a good copy of the gene. If the other mutation is advantageous, their survival means that the deleterious mutation persists. These deleterious mutations resemble the operation of a ratchet , in that the organism can never go back. By contrast, sexual reproduction allows most plants and animals to ...

Mutagen

... , 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. Mutagens are usually chemical compounds or radiation . The Ames test is one method to determine how ...

Natural selection

... Natural selection is distinguished from artificial selection by humans . Other mechanisms of evolution include genetic drift and gene flow . mutations create the genetic variation on which natural selection acts. It is important to note that the term "natural selection" is often used in the ...

Neurospora crassa

... in their experiments for which they won the Nobel Prize in Physiology or Medicine . Beadle and Tatum exposed N. crassa to x-rays, causing mutations . They then observed failures in metabolic pathways caused by errors in specific enzymes . This led to the "one gene, one enzyme" hypothesis ...

Neutral theory of molecular evolution

... or two isolated populations, most of their single-nucleotide differences can be assumed to have accumulated at the same rate as individuals with mutations are born. This latter rate, it has been argued, is predictable from the error rate of the enzymes that carry out DNA replication --enzymes that ...

Olfaction

... . Of these genes, only a portion code for functional odor receptors. Humans have 347 functional odor receptor genes; the other genes have nonsense mutations . This number was determined by analyzing the genome in the Human Genome Project ; the number may vary among ethnic groups, and does vary among ...

Prion

... new infectious material. Since the original hypothesis was proposed, a gene for the PrP protein has been isolated (the PRNP gene), several mutations that cause the variant shape have been identified and successfully cloned, and studies using genetically altered mice have bolstered the prion ...

Punctuated equilibrium

... summarized by Gould as follows: "Large, stable central populations exert a strong homogenizing influence [on the gene pool]. New and favorable mutations are diluted by the sheer bulk of the population through which they must ... [in] small, peripherally isolated groups [that] are cut off ...

Red Queen

... 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 their own. Second, it mixes up genes. Some genes might be advantageous only when paired with other genes, and sex increases the likelihood that ...

RNA virus

... three-dimensional structure which is hypothesized to provide a chemical function necessary for viral propagation. (See ribozyme .) If so, most mutations would render it unfit for that purpose and would not propagate. Some RNA viruses: Arenaviridae Bunyaviridae Flaviviridae : Yellow ...

Speciation

... a new species while the old species dies out, we have a process called anagenesis . Among simpler forms of life, such as bacteria , single mutations can cause drastic changes (called "saltation") that result in speciation in a very short time. Speciation is also related to a process known as ...

Splicing (genetics)

... when exonucleases begin to degrade the 3' end, the long trail of extra As takes extra time to degrade, elongating the mRNA's lifespan. mutations in the introns can prevent splicing and thus prevent protein biosynthesis . In many cases, the splicing process can create many unique proteins ...
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