Svedberg
Definition
- Noun:
- A unit of time: In physics and chemistry, a svedberg (symbol S) is a non-SI unit of measurement for sedimentation coefficient. It represents a time of 10⁻¹³ seconds (100 femtoseconds). It is used to describe the rate at which a particle sediments in an ultracentrifuge, which is related to its size and shape.
- Eponym: The unit is named after the Swedish chemist Theodor Svedberg (1884-1971), who won the Nobel Prize in Chemistry in 1926 for his work on disperse systems and the invention of the ultracentrifuge.
Usage Examples
- Noun:
- The ribosome has a sedimentation coefficient of 70 svedbergs.
- Scientists measured the protein's size to be approximately 4.5 S.
Advanced Usage
- Capitalization: While named after a person, the unit name "svedberg" is typically written in lowercase when used as a unit symbol (e.g., 40 S). The symbol is often capitalized (S) to distinguish it from the second.
- Context: The svedberg is primarily used in biochemistry and molecular biology to describe macromolecules and cellular components like ribosomes, viruses, and proteins based on their behavior during centrifugation.
Variants and Related Words
- Svedberg unit: A fuller name for the unit.
- Sedimentation coefficient: The physical property measured in svedbergs.
- Ultracentrifugation: The technique for which this unit is essential.
Synonyms
- S unit: An informal synonym.
- Sedimentation unit: A descriptive synonym.
Notes
- The svedberg is not a direct measure of mass, but of a sedimentation rate under specific conditions. Larger particles typically have higher svedberg values, but the relationship is not linear due to dependence on particle shape and density.
- It is common to see values like 5S, 16S, 23S, etc., when referring to ribosomal RNA components.
Noun
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Swedish theologian (1688-1772)
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