there are double rings in the purine bases and there is only a single ring in the pyrimidine base.
Purines because purines have two rings where as pyrimidines have only one ring.
It really depends on what you require from it.
Glucose has 6 carbons in its ring structure, so it forms a 6-membered ring. This means glucose has 6 sides in its ring structure.
No. It contains naphazoline, which is kinda sorta but not very much like a steroid. It has a five membered ring and two six membered rings it it (steroids have three six membered rings and one five membered rings). However, the five membered ring in naphazoline contains nitrogen (that in steroids does not) and the six membered rings are aromatic (those in steroids or not). So it's not a steroid, but if you were to glance at a spacefilling model and weren't a chemist I can see how you might mistake it for one.
sedoheptulose-diphosphate
pyranose is a collective noun of carbohydrates that have a six membered ring system which is 5 carbons and one oxygen. example: glucose Furanose is a collective noun of carbohydrates that have a five membered ring system which is 4 carbons and one oxygen. example: fructose
A beta-lactam is a lactam with a four-membered ring structure - a structural element of many antibiotics, including penicillin.
Nicotine contains a pyridine ring, which is a nitrogen-containing aromatic ring, and a pyrrolidine ring, which is a five-membered nitrogen heterocycle. These functional groups contribute to the biological activity of nicotine in the central nervous system.
Ribose is a five-carbon sugar with a five-carbon ring structure found in RNA molecules. Sugars with six carbon atoms, like glucose and fructose, typically form six-membered rings in their structures.
An azulene is a bicyclic aromatic hydrocarbon containing a five- and seven-membered fused ring.
The primary functional group in nicotine is the pyridine ring, which is a six-membered aromatic ring containing one nitrogen atom. Additionally, nicotine features a pyrrolidine ring, which is a five-membered saturated ring containing another nitrogen atom. These nitrogen atoms contribute to the basicity and overall pharmacological properties of nicotine.