How are the three parts of a nucleotide attached to one another?
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The three parts of a nucleotide, which are a phosphate group, a sugar molecule, and a nitrogenous base, are attached to one another through covalent bonds. Covalent bonds are formed when atoms share electrons.
To understand how the three parts of a nucleotide are attached, let's start with the sugar molecule. In DNA and RNA, the sugar molecule is either deoxyribose (in DNA) or ribose (in RNA). The sugar molecule contains a five-carbon ring structure.
Next, the phosphate group is attached to the sugar molecule. In DNA and RNA, the phosphate group contains one phosphorus atom bonded to four oxygen atoms. One of the oxygen atoms is bonded to the 5th carbon of the sugar molecule.
Finally, the nitrogenous base is attached to the sugar molecule as well. In DNA, there are four types of nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C). In RNA, uracil (U) replaces thymine. The nitrogenous base is attached to the 1st carbon of the sugar molecule.
To summarize, the phosphate group is attached to the 5th carbon of the sugar molecule, and the nitrogenous base is attached to the 1st carbon. Through these covalent bonds, the three parts of a nucleotide are connected to form a larger structure called a nucleic acid.