double helix
Học thuậtThân thiện
Definition
- Noun:
- A pair of parallel helices intertwined about a common axis: This is the specific, scientific term for the structure formed by two long, thin strands that coil around each other, sharing a central axis. It is most famously the shape of the DNA molecule.
Usage
- The term "double helix" is used almost exclusively in scientific contexts, particularly in biology, genetics, and biochemistry, to describe the molecular structure of DNA.
- It functions as a singular noun. The plural form is "double helices."
Examples
- Noun:
- The discovery of the DNA double helix was a landmark achievement in science.
- The model clearly shows the sugar-phosphate backbones forming the sides of the double helix.
- In a double helix, the two strands are complementary and anti-parallel.
Advanced Usage
- "The double helix": Often used with the definite article "the" to refer specifically to the structure of DNA as a general concept.
- The double helix is an icon of modern biology.
Variants and Related Words
- Helix (noun): A three-dimensional curve that lies on a cylinder or cone, making a constant angle with the straight lines parallel to the base. A single spiral. The double helix consists of two such helices.
- Alpha helix (noun): A common secondary structure in proteins, forming a single right-handed helical coil.
Synonyms
- DNA structure: A more general term that can refer to the double helix.
- Twisted ladder: A common metaphorical description of the double helix's shape, where the sugar-phosphate chains are the "rails" and the base pairs are the "rungs."
Related Phrases/Idioms
- "To unwind the double helix": A phrase describing the separation of the two DNA strands, which occurs during processes like replication and transcription.
- Enzymes help to unwind the double helix so its information can be read.
Noun
- a pair of parallel helices intertwined about a common axis
- the shape of the DNA molecule is a double helix