In baking, for example, flour and sugar are frequently measured in cups. A measuring cup is a physical container meant to hold 8 ounces. It is usually clear, and smaller units of measurement are marked on the outside using markers, including 1/2 cup, 1/3 cup and 1/4 cup.
Combinations of these atoms form the sugar-phosphate backbone of the DNA -- the sides of the ladder, in other words. Other combinations of the atoms form the four bases: thymine (T), adenine (A), cytosine (C), and guanine (G).These bases are the rungs of the DNA ladder.(It takes two bases to form a rung -- one for each side of the ladder.). A sugar molecule, a base, and a phosphate molecule group together to make up a nucleotide. Nucleotides are abundant in the cell's nucleus.Nucleotides are the units which, when linked sugar to phosphate, make up one side of a DNA ladder.hese bases are the rungs of the DNA ladder. (It takes two bases to form a rung -- one for each side of the ladder.). A sugar molecule, a base, and a phosphate molecule group together to make up a nucleotide. Nucleotides are abundant in the cell's nucleus.
Using research from many sources, including chemically accurate models, Watson and Crick discovered how these six subunits were arranged to make the the structure of DNA. The model is called a double helix because two long strands twist around each other like a twisted ladder. The rails of the ladder are made of alternating sugar and phosphate molecules. The steps of the ladder are made of two bases joined together with either two or three weak hydrogen bonds. Nucleotides The basic building block of DNA is called a NUCLEOTIDE. A nucleotide is made up of one sugar molecule, one phosphate molecule and one of the four bases. Here is the structural formula for the four nucleotides of DNA. Note that the purine bases (adenine and guanine) have a double ring structure while the pyrimidine bases (thymine and cytosine) have only a single ring.