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histone

(Encyclopedia)histone hĭsˈtōn [key], any of a class of protein molecules found in the chromosomes of eukaryotic cells. They complex with the DNA (see nucleic acid) and pack the DNA into tight masses of chromatin...

Todd, Sir Alexander Robertus

(Encyclopedia)Todd, Sir Alexander Robertus, 1907–97, Scottish biochemist, Ph.D., Univ. of Frankfurt am Main, 1931; Oxford, 1933. Todd held posts at Edinburgh Univ. (1934–36), the Lister Institute of Preventive ...

Wilkins, Maurice Hugh Frederick

(Encyclopedia)Wilkins, Maurice Hugh Frederick, 1916–2004, British biophysicist, b. New Zealand, Ph.D. Univ. of Birmingham, 1940. He conducted research at the Univ. of St. Andrews, Scotland, and at Kings College, ...

thymine

(Encyclopedia)thymine thīˈmēn [key], organic base of the pyrimidine family. Thymine was the first pyrimidine to be purified from a natural source, having been isolated from calf thymus and beef spleen in 1893–...

polymerase chain reaction

(Encyclopedia)polymerase chain reaction pŏlˈĭmərāsˌ [key] (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sa...

purine

(Encyclopedia)CE5 Purines found in deoxyribonucleic acid (DNA) purine, type of organic base found in the nucleotides and nucleic acids of plant and animal tissue. The German chemist Emil Fischer did much of the...

cytosine

(Encyclopedia)cytosine sīˈtōsēnˌ [key], organic base of the pyrimidine family. It was isolated from the nucleic acid of calf thymus tissue in 1894. A suggested structure for cytosine, published in 1903, was co...

phosphate

(Encyclopedia)phosphate, salt or ester of phosphoric acid, H3PO4. Because phosphoric acid is tribasic (having three replaceable hydrogen atoms), it forms monophosphate, diphosphate, and triphosphate salts in which ...

pyrimidine

(Encyclopedia)CE5 Pyrimidines found in deoxyribonucleic acid (DNA) pyrimidine pīrĭmˈĭdēnˌ [key], type of organic base found in certain coenzymes and in the nucleic acids of plant and animal tissue. The th...

gene

(Encyclopedia)gene, the structural unit of inheritance in living organisms. A gene is, in essence, a segment of DNA that has a particular purpose, i.e., that codes for (contains the chemical information necessary f...