What is Base 4. The nucleotide is the building block of two important macromolecules nucleic acids in the living organisms; that is, the DNA and RNA. Hence, they are the genetic material of an organism and are responsible for passing genetic characteristics from generation to generation. Furthermore, they are important to control and maintain cellular functions. Other than these two macromolecules, there are other important nucleotides.
According to the type of pentose sugar molecule, nitrogenous base, and the number of phosphate groups, nucleotides differ. There, the phosphate group of one nucleotide links with the —OH group of carbon 5 of the sugar to form these macromolecules. However, in ATP, there are three phosphate groups. The linkages between phosphate groups are high energy bonds. Moreover, the other nucleotides are derivatives of these.
Many other functions of the various nucleosides and nucleotides will be explored in later chapters. Nucleosides and nucleotides are closely involved in the preservation and transmission of the genetic information of all living creatures. In addition, they play roles in biological energy storage and transmission, signaling, regulation of various aspects of metabolism, and even an important role as an antioxidant.
Mistakes or deficiencies in their synthesis usually lead to death. Overproduction or decreased elimination of nucleic acid derivates also lead directly to medical conditions. Nucleosides have a nitrogenous base and a five-carbon carbohydrate group, usually a ribose molecule see Chapter 2.
Nucleotides are simply a nucleoside with one or more phosphate groups attached Figure The resulting molecule is found in ribonucleic acid or RNA. If one hydroxyl OH group has been removed from the ribose, the deoxy versions of the nucleoside and nucleotide form the building blocks of deoxyribonucleic acid or DNA Figure Each component of nucleosides and nucleotides is discussed below.
Basic Structure of Nucleosides and Nucleotides. Five major nucleoside bases are common in human biology, including the purines two-ring structure adenine and guanine top and the pyrimidines one-ring structure cytosine, uracil, and thymine middle. Nucleosides bottom are made of a nitrogenous base, usually either a purine or pyrimidine, and a five-carbon carbohydrate ribose.
A nucleotide is simply a nucleoside with an additional phosphate group or groups blue ; polynucleotides containing the carbohydrate ribose are known as ribonucleotide or RNA. Nitrogenous base—The nitrogenous base of a nucleoside or nucleotide named because of the nitrogen atoms found in its structure may be either a purine or a pyrimidine. Recall some basic structural features of the nucleotide building blocks of DNA. A nucleotide is composed of a nitrogenous base, deoxyribose five-carbon sugar , and at least one phosphate group.
The nitrogenous bases are purines such as adenine A and guanine G , or pyrimidines such as cytosine C , thymine T , and uracil U. This type of bond is called a glycosidic bond.
The phosphate group forms a bond with the deoxyribose sugar through an ester bond between one of its negatively charged oxygen groups and the 5' -OH of the sugar.
Nucleotides join together through phosphodiester linkages between the 5' and 3' carbon atoms to form nucleic acids. The 3' -OH of the sugar group forms a bond with one of the negatively charged oxygens of the phosphate group attached to the 5' carbon of another sugar. When many of these nucleotide subunits combine, the result is the large single-stranded polynucleotide or nucleic acid, DNA.
If you look closely, you can see that the two sides of the nucleic acid strand shown above are different, resulting in polarity. At one end of the large molecule, the carbon group is unbound and at the other end, the -OH is unbound.
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