![]() These are the most common base pairing patterns but alternative patterns also are possible. As shown in figure 3, adenine forms a base pair with thymine, and guanine forms a base pair with cytosine. The interaction between two bases on opposite strands via hydrogen bonds is called base pairing. It is the sequence of these four bases that encode genetic information. In DNA,the nucleotide is a deoxyribonucleotide (in RNA, the nucleotide is a ribonucleotide). A nucleotide is made of a phosphate + a sugar + a nitrogenous base. During the polymerization process, deoxynucleotide triphosphates (dNTP) are used. A nucleoside is made of a sugar + a nitrogenous base. Phosphodiester bonding between nucleotides forms the sugar-phosphate backbone, the alternating sugar-phosphate structure composing the framework of a nucleic acid strand ( Figure 10.13 ). The bases interact via hydrogen bonds with complementary bases on the other DNA strand in the helix. Primary structure of the molecule:covalent backbone and bases aside. Its structure is described as a double-stranded helix held together by complementary base pairs. The four bases are adenine (A), cytosine (C), guanine (G) and thymine (T). The sugar and phosphate create a backbone down either side of the double helix. Nucleotides have three components: a base, a sugar (deoxyribose) and a phosphate residue. The monomers of DNA are called nucleotides. Some DNA sequences do not code for genes and have structural roles (for example, in the structure of chromosomes), or are involved in regulating the use of the genetic information for example, repressor sites are DNA sequences that allow binding of a repressor, which stops the process of gene expression.ĭNA consists of two long polymers (called strands) that run in opposite directions and form the regular geometry of the double helix. Genes are the DNA segments that carry genetic information (1). Therefore, DNA is an essential component of independently living organisms. The bases come in two categories: thymine and cytosine are pyrimidines, while adenine and guanine are purines ().
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |