In classical population genetics, polymorphism refers to the coexistance of different alleles in a population/species at significant frequencies (the most frequent allele should be less than 95%%). However, the term polymorphism is frequently used simply to indicate that genetic variation occurs within a certain part of the genome. In extreme, polymorphism can refer to just one nucleotide, e.g., SNP.
1. The occurrence of allelic variation at a locus. Polymorphism in nucleotide sequences has provided powerful diagnostic tools. See: DNA diagnostics, microsatellites, restriction fragment length polymorphism. 2. The occurrence of two or more forms in a population.
A polymorphism is a place in the human genome where a base can take on multiple forms. For example, a certain base may be A in one person and C in another. The length of some sections of DNA are also polymorphic. For example a particular segment may be 12 bases long in some people and 21 bases in others.
Frequently occurring (common), usually normal variation, in a defined nucleotide sequence. Polymorphisms in genes may result in protein polymorphisms. A protein polymorphism is said to occur when the most common allele has a frequency of no greater than 99%.
(pol´ lee mor´ fiz um) [Gr. poly: many + morphe: form, shape] • (1) In genetics, the coexistence in the same population of two distinct hereditary types based on different alleles. (2) In social organisms such as colonial cnidarians and social insects, the coexistence of two or more functionally different castes within the same colony.
The simultaneous occurrence of two or more versions of a gene in a population.In mitochondrial DNA, it usually refers to different bases at a particular position, such as A750G.The frequency of the rarest form of the polymorphism is higher than can be maintained by recurrent mutation.
Differences in DNA sequences that occur naturally in a population. Single nucleotide substitutions, insertions and deletions of nucleotides and repetitive sequences (microsatellites) are all examples of a polymorphism. The position at which such a sequence difference is found is a polymorphic site.
in this context, the existence of inter-individual differences in DNA sequences coding for one specific gene. The effects of such differences may vary dramatically, ranging from no effect at all to the building of inactive proteins.
The combination of multiple allelic forms and polygenic structure, causes a large number of different gene combinations to be formed. This gives rise to the variablilty of some proteins, such as the MHC.
A genetic term. Polymorphisms are changes in the genetic code (like mutations) that occur commonly enough in the population such that they are considered a variation on normal. These may be harmful, helpful or neither to the persons who have a polymorphism.
Frequently occurring variation in a nucleotide sequence. Polymorphisms in genes result in protein polymorphisms. A polymorphism is said to occur when the most common allele has a frequency of no greater than 99 percent. Some forms of some polymorphisms are associated with increased risk of disease.
A trait of an organism that is found in more than one state in a population. Also used for the existence of different forms of a gene in a population. For example, one well known polymorphism of color vision is the existence of both red-green dichromats and normal trichromats in the human population.
(lit. many forms) The existence of a gene in a population in at least two different forms at a frequency far higher than that attributable to recurrent mutation alone. Variations in a population may be measured by determining the rate of mutation in polymorphic genes (see SNPs).
1) The existence of more than one form or type in a species, beyond simple gender differences. Social insects such as honeybees with queens, drones, and workers demonstrate polymorphism. 2) Another term for pleomorphism, the occurrence of distinct forms during the life cycle of a plant or animal, such as the caterpillar and pupa that precede the adult.
A segment of DNA that has more than one form (allele), each of which occurs at a frequency of at least 1%. Polymorphisms are a natural part of genetic variation. A polymorphism in a gene may or may not affect its function.
Natural variations in a gene, DNA sequence, protein, or chromosome that have no adverse effect on the individual and occur with fairly high frequency in the general population Related Terms: allele ; allelic variant of unknown significance ; benign variant ; mutation ; restriction fragment length polymorphism
These sequence variations, or polymorphisms, make up many of the landmarks on modern genetic-linkage maps ... (IOCeleraGenome) Polimorfismo A seqüência contida no clone P3 não detectou nenhum polimorfismo enquanto que as seqüências... (POUniverRS)
having multiple forms of an allele at a locus within a population. Forensic scientists look for areas of DNA that are polymorphic because these allow people to be told apart from each other by their DNA.
Genetic variation. An enzyme that is expressed in some individuals but not others is said to be a polymorphic enzyme, as are enzymes that are encoded by the same gene locus but differ by one or more amino acids. These latter enzymes are also known as allelic variants or allelozymes.
In biology, polymorphism (from Greek: poly "many", morph "form") can be defined as discontinuous genetic variation that results in the occurrence of several different forms or types of individuals among the members of a single species. The most obvious example of polymorphism is the separation of most higher organisms into male and female sexes. Another classic example is the different melanic and non-melanic morphs of the peppered moth.
The capability of an operation to accept arguments of different or unknown types. Parametric polymorphism executes the same operation on different types. Overloading polymorphism selects appropriate operations according to the type.
Polymorphism refers to the ability of the same message to be sent to different objects with different results. Thus the + operator might be sent to an integer to perform integer arithmetic, or to a floating point number to perform floating point arithmetic, or to a string to perform concatenation. Dreams exhibits polymorphism implicitly due to the dynamic binding nature of method determination.
The ability of a chemical compound to crystallize with more than one kind of crystal structure. For example Al2SiO, may crystallize as three different minerals, depending on the prevailing temperature and pressure.
Technically, a concept from type theory whereby a strongly-typed function may accept values of more than one type (constrasts with monomorphism). Object-oriented languages exhibit polymorphism in three ways: inheritance an inherited method is polymorphic, because it applies uniformly to all object types under the class in which it is defined; overloading an overloaded method selects one from a family of methods according to the type of object - the calling expression is polymorphic; templates a paramterised method is polymorphic, because it applies uniformly to each type of object obtained by replacing the type parameter(s).
The ability of different objects to respond to the same message in different ways. This means that different objects can have very different method implementations for the same message. An object can send a message without concern for its underlying implementation.
This is the ability to have two different objects of two different types both implement the same method. It lets you write code that calls that method regardless of which type of object is in use at the moment.
The method invoked by a particular message depends on the object which receives it. For example, you could implement several different classes of bank account object (checking, savings, high rate). All bank account objects would respond to the message"printStatement". However, each different type of account would implement "printStatement" differently, in a way appropriate to itself – savings accounts show interest paid, but checking accounts don't. Polymorphism enables you to send the same message ("printStatement") to any type of account object and get appropriate results.
"A concept in type theory, according to which a name (such as a variable declaration) may denote objects of many different classes that are related by some common superclass; thus, any object denoted by this name is able to respond to some common set of operations in different ways." 1 Method overloading is also considered by some to be a form of polymorphism.
Allows code to be written in a general fashion to handle existing and future related classes. Properly developed, the same behavior can act differently depending on the derived object it acts on. With an automobile, the acceleration behavior might be different for a station wagon and a dragster which are subclasses of the superclass automobile. The function would still be accelerate(), but the version would vary (this may sound confusing, but the compiler keeps track and figures it all out).
When a single algorithm is applicable to multiple types. Compile time polymorphism is provided in Ada via generic units. Instantiation as compile-time is used to specialize a generic unit to a particular type. Ada 95 also supports run-time polymorphism -- where a run-time type tag can be used to control which subprogram body is executed when a polymorphic algorithm calls a primitive operation with an operand of class-wide type.
based on the self-encryption technique, a virus encrypts its code in a different manner each time it infects (its signature changes each time). Through polymorphism, however, the virus also encrypts the routine or algorithm it uses to encode its signature. This means that the virus can create variants of itself that are completely different from one infection to another. To detect these complex viruses, antivirus programs use decryption simulation techniques.
Basically polymorphism is about transparently substituting one implementation for another. There is little need for substituting data implementations, so we are mostly concerned with behavior substitution. There are several forms of polymorphism supported for OO development: ad hoc, inclusion, overload, and parametric are the main ones of interest. (See categories on what OO is all about and relationships.)
Polymorphism is when the same method is interpreted differently by different objects. For a real world example, a telephone class has a ring method. A cell phone has a different ring that an older phone with mechanical bells. But when calling someone, the Phone.Ring() implementation doesn't matter - due to polymorphism, the two objects have the same interface with different implementations.
A property of class¤ hierarchies whereby the result of calling a specific virtual member¤ function¤ of an object depends on the actual (run-time) type of the object, rather than on the (compile-time) type of the pointer or reference¤ through which the call is initiated.
A virus is said to be polymorphic if its code appears to be different every time it replicates (though generally each replication of the virus is functionally identical). This is usually achieved by encrypting the body of the virus, and adding a decryption routine which is different for each replication. When a polymorphic virus replicates, a portion of the decryption code is modified. Additionally, random, do-nothing blocks of code can be embedded in the program and are shuffled around to further vary the signature. In essence, it looks like a different program to virus scanners.
A virus that attempts to evade detection by changing its internal structure or its encryption techniques. Polymorphic viruses change form with each infection to avoid detection by anti-viral software scanning for signature forms. Less sophisticated systems are referred to as self-encrypting.
"Literally to take many forms. In object-oOriented design, subclasses of a class implement the public interface to the parent class in such a way that a message sent to a collection of parents and children would be responded to by each appropriately, without the caller knowing."