In DNA , the attached sugar is deoxyribose. Nucleosides have slightly different names than their nitrogenous base parents, and depend upon the identity of the sugar. What is the identity of the nucleoside displayed in the computer model?
A nucleoside with one or more phosphate groups attached to the sugar is called a nucleotide. The name of a nucleotide is the corresponding nucleoside name, followed by the word 'monophosphate,' 'diphosphate,' or 'triphosphate' to indicate the number of phosphate groups attached to the sugar.
Click the button below to examine the structure of a nucleotide triphosphate. What is the identity of the nucleotide triphosphate displayed in the computer model? Adenosine triphosphate ATP. Deoxyadenosine triphosphate dATP. Guanosine triphosphate GTP. Deoxyguanosine triphosphate dGTP. Thymidine triphosphate TTP. Click the button below to examine the structure of deoxyadenine monosphosphate dAMP. Notice the angle of the sugar and phosphate groups in relation to the planar nitrogenous base.
In double-stranded DNA, two long molecules twist around one another in a double helix. These molecules are d eoxy n ucleic a cids DNA : polymers made up of nucleotides In a DNA double helix, the phosphate and sugar groups make up the outer 'backbones,' and the flat nitrogenous bases are pointed toward the middle of the helix.
There is a tightly packaged region that stains darkly, and a less dense region. The darkly staining regions usually contain genes that are not active, and are found in the regions of the centromere and telomeres. The lightly staining regions usually contain genes that are active, with DNA packaged around nucleosomes but not further compacted.
Concept in Action. Watch this animation of DNA packaging. The DNA molecule is a polymer of nucleotides. Each nucleotide is composed of a nitrogenous base, a five-carbon sugar deoxyribose , and a phosphate group. There are four nitrogenous bases in DNA, two purines adenine and guanine and two pyrimidines cytosine and thymine. A DNA molecule is composed of two strands.
Each strand is composed of nucleotides bonded together covalently between the phosphate group of one and the deoxyribose sugar of the next. From this backbone extend the bases. The bases of one strand bond to the bases of the second strand with hydrogen bonds. Adenine always bonds with thymine, and cytosine always bonds with guanine. The bonding causes the two strands to spiral around each other in a shape called a double helix. Ribonucleic acid RNA is a second nucleic acid found in cells.
RNA is a single-stranded polymer of nucleotides. From what Chargaff discovered he noticed some patterns in the molar concentrations of the bases, from his results he devised some rules [5]. In the DNA double helix, as well as the bases being complementary base-paired they are also stacked on top of one another.
These bases also have interactions Van der Waals happening between one another which also contribute towards the DNAs structure. Base stacking in this way creates a hydrophobic core on the DNA [6].
Jump to: navigation , search. O hydrogen bond being essentially linear. The bottom line is that there is a trace of Pauling in the double helix. You can also search for this author in PubMed Google Scholar. Reprints and Permissions. Wain-Hobson, S. The third Bond. Nature , Download citation. Published : 01 February Issue Date : 02 February Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
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