sport

(redirected from a sporting chance)
Also found in: Dictionary, Thesaurus, Medical, Idioms.

mutation

mutation, in biology, a sudden, random change in a gene, or unit of hereditary material, that can alter an inheritable characteristic. Most mutations are not beneficial, since any change in the delicate balance of an organism having a high level of adaptation to its environment tends to be disruptive. As the environment changes, however, mutations can prove advantageous and thus contribute to evolutionary change in the species. In higher animals and many higher plants a mutation may be transmitted to future generations only if it occurs in germ, or sex cell, tissue; somatic, or body cell, mutations cannot be inherited except in plants that propagate asexually (see reproduction). Sometimes the word mutation is used broadly to include variations resulting from aberrations of chromosomes; in chromosomal mutations the number of chromosomes may be altered, or segments of chromosomes may be lost or rearranged. Changes within single genes, called point mutations, are actual chemical changes to the structure of the constituent DNA.

Point Mutations

Each gene is made up of a long sequence of substances called nucleotides; these nucleotides, taken in series of three at a time, specify each amino acid subunit of a protein (see nucleic acid). In a frameshift mutation, a nucleotide is added or deleted to the sequence and the decoding of the entire gene sequence will be radically altered and the amino acid sequence of the protein produced will also be very different. Often the resulting protein is totally ineffective. If one nucleotide substitutes for another in the sequence only one amino acid of the protein will be different, but the effect can be quite dramatic. 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.

Because proteins called enzymes control most cell activities, a mutation affecting an enzyme can result in alteration of other cell components. A single gene mutation may have many effects if the enzyme it controls is involved in several metabolic processes. Occasionally a mutation can be offset by either another mutation on the same gene or on another gene that suppresses the effect of the first. Certain genes are responsible for producing enzymes that can repair some mutations. While this process is not fully understood, it is believed that if these genes themselves mutate, the result can be a higher mutation rate of all genes in an organism.

Induced Mutations

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. H. J. Muller, an American geneticist, pioneered in inducing mutations by X-ray radiation (using the fruit fly, Drosophila) and developed a method of detecting mutations that are lethal.

Mutation and Evolution

In 1901 the observation of mutants, or sports, among evening primrose plants led the Dutch botanist Hugo de Vries to present his theory that new characteristics may appear suddenly and that these characteristics are inheritable; before this time the sources of evolutionary variation were not known and some still believed that evolution resulted from a gradual selection of favorable acquired characteristics. The work of de Vries and of subsequent investigators who demonstrated the distinction between mutation and environmental variations has shown the importance of mutation in the mechanism of evolution.

Bibliography

See W. Gottschalk and G. Wolff, Induced Mutations in Plant Breeding (1983); G. Obe, Mutations in Man (1984).

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.

sport

individual or group recreational activities, usually physical, which involve interpersonal or intergroup competition, contests with nature (e.g. hunting), or the more general exercise of physical skills. While sports often take the form of‘games’, not all games are sports (e.g. card games, various games of chance and strategy). Sport occurs in most societies. However, most modern forms of organized sport have their origins in the latter half of the 19th century, although some of these, such as horse racing, boxing, cricket and football have a much longer history. In modern societies the role of sport – including spectator and televised sport – is a significant one. See also SOCIOLOGY OF SPORT, PLAY, LEISURE.
Collins Dictionary of Sociology, 3rd ed. © HarperCollins Publishers 2000

What does it mean when you dream about sports?

Dreaming of participating in a sport may suggest that the dreamer is in excellent physical condition or needs some exercise or recreation.

The Dream Encyclopedia, Second Edition © 2009 Visible Ink Press®. All rights reserved.

sport

Biology
a. an animal or plant that differs conspicuously in one or more aspects from other organisms of the same species, usually because of a mutation
b. an anomalous characteristic of such an organism
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

Sport

(dreams)
Playing sports may represent some aspects of the way that we run our lives, or may refer to internal struggles where one part of the dreamer’s psyche or personality is attempting to “win” over another. At times life is like a challenging sport. We compete, try to win, and attempt to develop our abilities so that we will succeed. In the dream, the outcome of the game may say something about how well we are doing. Do we feel competent and successful, are we playing fair, or is the sport more competitive than what we are comfortable with? In order to understand the dream, consider the details and attempt to identify what in daily life creates similar emotions. All sports and games have specific rules and boundaries. Your performance within this framework may represent the struggle against inner conflicts such individual fears and weaknesses, or may be referring to a pragmatic problem or situation at work or in your relationships.
Bedside Dream Dictionary by Silvana Amar Copyright © 2007 by Skyhorse Publishing, Inc.