Nucleic acids are made up of three kinds of monomer units: heterocyclic aromatic amine bases produced from purine and pyrimidine, d-ribose or 2-deoxy-d-ribose, and phosphate ions.

• The four bases of DNA are adenine, cytosine, guanine, and thymine.

• The four nucleotides for RNA are adenine, cytosine, guanine, and uracil.

• Purines are adenine and guanine, whereas pyrimidines are cytosine, thymine, and uracil.

• A nucleotide is a nucleoside in which at least one molecule of phosphoric acid is esterified with a monosaccharide's iOH, most typically the 39-OH or the 59-OH.

At pH 7.0, nucleoside mono-, di-, and triphosphates are powerful polyprotic acids that are substantially ionized.

Adenosine triphosphate, for example, is a 50:50 combination of ATP32 and ATP42 at pH 7.0.

• The term nucleoside refers to a compound containing d-ribose or 2-deoxy-d-ribose bonded to a heterocyclic aromatic amine base by a b-N-glycosidic bond.

The main structure of deoxyribonucleic acid (DNA) is made up of 29-deoxyribose units linked together by 39,59-phosphodiester linkages.

• A b-N-glycosidic link connects each deoxyribose unit to a heterocyclic aromatic amine base. The base sequence is read from the 59th to the 39th end of the polynucleotide strand.

• The Watson-Crick model is based on the idea that a DNA molecule is made up of two antiparallel polynucleotide strands coiled in a right-handed way around the same axis to create a double helix.

• Purine and pyrimidine bases point inward toward the helix's axis and are always coupled G-C and A-T due to unique hydrogen bonding patterns.

Base pairs in B-DNA are layered one on top of the other with a gap of 340.

• Bases in A-DNA are stacked with 290 pm spacing between base pairs and ten base pairs every 2900 pm helical repetition.

• Supercoiling is a term used to describe the tertiary structure of DNA.

• Circular DNA is a kind of double-stranded DNA in which phosphodiester groups connect the ends of each strand.

Opening one strand, followed by partial unwinding and reconnecting of the ends, adds tension to the nonhelical gap.

• By introducing superhelical twists, this strain may be distributed over the whole molecule of circular DNA.

• Histones are DNA binding proteins that are present in cell nuclei.

• They are particularly high in lysine and arginine, and so contain a high concentration of positive charges.

• The interaction between DNA with histones results in the formation of chromatin.

The main structure of ribonucleic acids (RNA) and DNA differs significantly in two ways.

• D-ribose is the monosaccharide molecule of RNA.

• The purine bases adenine (A) and guanine (G), as well as the pyrimidine nucleotide cytosine, are found in both RNA and DNA (C).

• However, RNA has uracil (U) as the fourth nucleotide, whereas DNA contains thymine (T).

• In cells, RNA occurs in three different forms.

• The most prevalent type, ribosomal RNA, is found in the ribosome, the cell's protein-synthesizing mechanism.

Transfer RNA transports amino acids to protein synthesis sites on ribosomes.

• Messenger RNAs are copies of DNA gene sequences that transport coded genetic information from DNA to ribosomes for protein production.

• Restriction endonucleases identify a specific pattern of four to eight nucleotides and cleave a DNA strand by hydrolyzing the connecting phosphodiester links at any place containing that sequence.

Various restriction endonucleases from different sources recognize different sequences. To generate fragments from genomic DNA, restriction endonucleases are utilized.

• A primer-DNA template is separated into four independent reaction mixes in Frederick Sanger's chain termination or dideoxy technique of DNA sequencing.

• The four dNTPs, one of which is designated with 32P, are added to each.

• DNA polymerase and one of the four ddNTPs are also included.

When a ddNTP is introduced, synthesis is halted.

Polyacrylamide gel electrophoresis is used to separate mixtures of newly generated oligonucleotides, which are then visualized by autoradiography.

• The base sequence of the DNA complement to the original DNA template is read from the bottom to the top of the produced photographic plate (from the 59 end to the 39 end).

• Enzymatic DNA sequencing processes are combined with clonal amplification, microfabrication, microfluidics, and automated sample preparation in next-generation DNA sequencing technologies.

• Entire genomes with many gigabases of data are now regularly determined.

Each sequence read generally consists of 50 to 400 base pairs. Powerful computers using advanced sequence alignment and overlapping algorithms compile thousands to millions of these reads into full genomic sequences.

• The incredible potency of this technology has sparked a biological revolution with far-reaching implications for medicine.

• Alternatively, the four ddNTPs each have a separate fluorescent label, and the sequence is read as the fluorescing ddNTPs.