Prokaryotic cells

Eukaryotic chromosomes are found in a special compartment called the cell nucleus. The genomes of bacterial cells (prokaryotes ), which lack a nucleus, are typically circular DNA molecules that associate with special structures in the cell membrane.

DNA does not usually exist as a single strand, but instead as a pair of strands that are held tightly together. These two long strands coil around each other, in the shape of a double helix.

DNA viruses comprise important pathogens such as herpesviruses, smallpox viruses, adenoviruses, and papillomaviruses, among many others.

Studies with synchronised human cells have shown that single-stranded DNA is mainly found during the period of DNA synthesis3,4. We have repeatedly observed by electron microscopy long single-stranded stretches of host DNA that initially co-purified with the guanine–cytosine-rich viral episomal DNA.

DNA exists in the nucleus as a condensed, compact structure. DNA single-stranded binding proteins – These proteins bind to the DNA as a tetramer and stabilize the single-stranded structure that is generated by the action of the helicases.

The DNA molecules are not always double stranded helical structures, sometimes they occur in single stranded form called ssDNA….ssDNA vs dsDNA – A Comparison Table.

A DNA molecule consisting of only a single strand contrary to the typical two strands of nucleotides in helical form. In nature, single stranded DNA genome can be found in Parvoviridae (class II viruses).

Aptasensors. Nucleic acid aptamers are short, single-stranded DNA or RNA oligonucleotides, which adopt stable three-dimensional sequence-dependent structures.

Like DNA, each RNA strand has the same basic structure, composed of nitrogenous bases covalently bound to a sugar-phosphate backbone (Figure 1). However, unlike DNA, RNA is usually a single-stranded molecule.

Abstract. Enzyme immunoassay (EIA) to detect IgG antibodies to single-stranded DNA (ssDNA EIA) and EIA to detect anti double-stranded DNA antibodies (dsDNA EIA) have been developed and widely used in Japan.

n. A nucleic acid that carries the genetic information in cells and some viruses, consisting of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine.

The strands of a DNA double helix are said to be “antiparallel” because they have the same chemical structure, but are opposite in direction. The direction of a DNA strand is also known as “polarity”.

The sugar-phosphate backbone of DNA is polar, and therefore hydrophillic; thus it likes to be proximal to water. The interior portion of DNA, the bases, are relatively non-polar and therefore hydrophobic.

Because one side of each sugar molecule is always connected to the opposite side of the next sugar molecule, each strand of DNA has polarity: these are called the 5′ (5-prime) end and the 3′ (3-prime) end, in accordance with the nomenclature of the carbons in the sugars.

Because DNA is negatively charged, molecular biologists often use agarose gel electrophoresis to separate different sized DNA fragments when DNA samples are subjected to an electric field — due to their negative charge, all the DNA fragments will migrate toward the positively charged electrode, but smaller DNA …

Phosphate groups

pH 5 to 9

DNA or RNA are called nucleic acids because of the acidic nature of the phosphate group attached to them. The phosphodiester bond can easily lose the proton in the presence of nucleophile group subsequently masking the basic nature of nitrogenous bases.