| 영문 | nucleic acid | 한글 | 핵산 |
|---|---|---|---|
| 설명 | 염기, 당, 인산으로 이루어진 뉴클레오티드가 긴 사슬 모양으로 중합된 고분자 물질. 유전이나 단백질 합성을 지배하는 중요한 물질로, 생물의 증식을 비롯한 생명 활동 유지에 중요한 작용을 한다. 구성 당인 오탄당이 리보오스인 리보핵산과 디옥시리보오스인 디옥시리보 핵산으로 나뉜다. 펜토스로서 리보스나 데옥시리보스 어느 한쪽만을 포함하며 전자를 리보핵산(RNA), 후자를 데옥시리보핵산(deoxyribonucleic acid, DNA)이라 부른다. 모두 4종류의 유기염기에 의해 특징지어지며 아데닌, 구아닌 및 시토신은 양자에 공통이다. 티민은 DNA에, 우라실은 RNA에 포함된다. DNA는 주로 핵에 존재하며 형질유전에 그리고 RNA는 세포질속에서 단백질 합성에 관여한다. 섭취된 핵산은 소화관에서 구성분자로까지 가수분해되어 흡수된다. |
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| activation analysis | <radiobiology> Method for identifying and measuring chemical elements in a sample of material. Sample is first made radioactive by bombardment with neutrons, charged particles, or gamma rays. Newly formed radioactive atoms in the sample then give off characteristic radiations (such as gamma rays) that tell what kinds of atoms are present, and how many. (09 Oct 1997) |
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| activation energy | <chemistry> The amount of energy (expressed in joules) that is needed to convert all the molecules in one mole of a reacting substance from a ground state to the transition state. (06 May 1997) |
| activation product | <radiobiology> The unstable nucleus formed when activation occurs. (See activation above.) (09 Oct 1997) |
| macrophage activation | The process of altering the morphology and functional activity of macrophages so that they become avidly phagocytic. It is initiated by lymphokines, such as the macrophage activation factor (maf) and the macrophage migration-inhibitory factor (mmif), immune complexes, c3b, and various peptides, polysaccharides, and immunologic adjuvants. (12 Dec 1998) |
| gene activation | The process of activation of a gene so that it is expressed at a particular time. This process is crucial in growth and development. (05 Mar 2000) |
| Gibbs energy of activation | The Gibbs energy that must be added to that already possessed by a molecule or molecules in order to initiate a reaction. (05 Mar 2000) |
| virus activation | The mechanism by which latent viruses, such as genetically transmitted tumour viruses or prophages of lysogenic bacteria, are induced to replicate and are released as infectious viruses. It may be effected by various endogenous and exogenous stimuli, including B-cell lipopolysaccharides, glucocorticoid hormones, halogenated pyrimidines, ionizing radiation, ultraviolet light, and superinfecting viruses. (12 Dec 1998) |
| cis activation | <molecular biology> Activation of a gene by an activator located on the same chromosome i.e. Not by a diffusible product. (18 Nov 1997) |
| complement activation | The sequential activation of serum components c1 through c9, initiated by an erythrocyte-antibody complex or by microbial polysaccharides and properdin, and producing an inflammatory response. (12 Dec 1998) |
| platelet activation | A series of progressive, overlapping events triggered by exposure of the platelets to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable haemostatic plug. (12 Dec 1998) |
| neutron activation analysis | Activation analysis in which the specimen is bombarded with neutrons. Identification is made by measuring the resulting radioisotopes. (12 Dec 1998) |
| neutrophil activation | The process in which the neutrophil is stimulated by diverse substances, resulting in degranulation and/or generation of reactive oxygen products, and culminating in the destruction of invading pathogens. The stimulatory substances, including opsonised particles, immune complexes, and chemotactic factors, bind to specific cell-surface receptors on the neutrophil. (12 Dec 1998) |
| EEG activation | The low voltage, fast pattern of attentive wakefulness. (05 Mar 2000) |
| trans-activation (genetics) | Increased rate of gene expression directed by either viral or cellular proteins. These regulatory factors (diffusible gene products) act in trans -- that is, act on homologous or heterologous molecules of DNA. (cis-acting factors act only on homologous molecules.) (12 Dec 1998) |
| energy of activation | Energy that must be added to that already possessed by a molecule or molecules in order to initiate a reaction; usually expressed in the Arrhenius equation relating a rate constant to absolute temperature. (05 Mar 2000) |