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The nucleotides forming each DNA strand are connected by noncovalent bonds, called hydrogen bonds. Considered individually, hydrogen bonds are much weaker than a single covalent bond, such as a phosphodiester bond. But, there are so many of them that the two DNA polymers are very strongly connected to each other.
Figure 2: The four nitrogenous bases that compose DNA nucleotides are shown in bright colors: adenine (A, green), thymine (T, red), cytosine (C, orange), and guanine (G, blue).
DNA structure. DNA is a nucleic acid, one of the four major groups of biological macromolecules. Nucleotides. All nucleic acids are made up of nucleotides. In DNA, each nucleotide is made up of three parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base.
DNA normally exists as a two antiparallel complementary strands held together by hydrogen bonds between adenines (A) and thymines (T), and between guanines (G) and cytosines (C). DNA is normally found as a double-stranded molecule in the cell whereas RNA is mostly single-stranded.
Color the bases on the DNA: The combination of a single base, a deoxyribose sugar, and a phosphate make up a nucleotide. DNA is actually a molecule of repeating nucleotides. Examine the nucleotides closer. Two of the bases are purines - adenine and guanine. The pyrimidines are thymine and cytosine.
The building blocks of DNA are nucleotides, which are made up of three parts: a deoxyribose (5-carbon sugar), a phosphate group, and a nitrogenous base (Figure \ (\PageIndex {2}\)). There are four types of nitrogenous bases in DNA.
DNA is made of four types of nucleotides, which are linked covalently into a polynucleotide chain (a DNA strand) with a sugar-phosphate backbone from which the bases (A, C, G, and T) extend. A DNA molecule is composed of two (more...)
