^ m d. In the document, Nursing: Scope and Standards of Practice, scope of practice is defined by the âwho,â âwhat,â âwhere,â âwhen,â âwhy,â and âhowâ of nursing practice, including advanced practice nursing. In addition, there are other documents relevant to specialties.
double helix. double helix. double helix. The coiled structure of double-stranded DNA in which strands linked by hydrogen bonds form a spiral configuration, with the two strands oriented in opposite directions.
In 1953 James Watson and Francis Crick published their theory that DNA must be shaped like a double helix. In 1953 James Watson and Francis Crick published their theory that DNA must be shaped like a double helix. A double helix resembles a twisted ladder. Each 'upright' pole of the ladder is formed from a backbone of alternating sugar and phosphate groups. Each DNA base (adenine, cytosine, guanine, thymine) is attached to the backbone and these bases form the rungs. There are ten 'rungs' for each complete twist in the DNA helix.