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Molecular composition and size

Nucleic acids can vary in size, but are generally very large molecules. Indeed, DNA molecules are probably the largest individual molecules known. Well-studied biological nucleic acid molecules range in size from 21 nucleotides (small interfering RNA) to large chromosomes (human chromosome 1 is a single molecule that contains 247 million base pairs.

In most cases, naturally occurring DNA molecules are double-stranded and RNA molecules are single-stranded. There are numerous exceptions, however-some viruses have genomes made of double-stranded RNA and other viruses have single-stranded DNA genomes, and, in some circumstances, nucleic acid structures with three or four strands can form.

Nucleic acids are linear polymers (chains) of nucleotides. Each nucleotide consists of three components: a purine or pyrimidine nucleobase (sometimes termed nitrogenous base or simply base), a pentose sugar, and a phosphate group. The substructure consisting of a nucleobase plus sugar is termed a nucleoside. Nucleic acid types differ in the structure of the sugar in their nucleotides - DNA contains 2'-deoxyribose while RNA contains ribose (where the only difference is the presence of a hydroxyl group). Also, the nucleobases found in the two nucleic acid types are different: adenine, cytosine, and guanine are found in both RNA and DNA, while thymine occurs in DNA and uracil occurs in RNA.

The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphodiester linkages. In conventional nomenclature, the carbons to which the phosphate groups attach are the 3'-end and the 5'-end carbons of the sugar. This gives nucleic acids directionality, and the ends of nucleic acid molecules are referred to as 5'-end and 3'-end. The nucleobases are joined to the sugars via an N-glycosidic linkage involving a nucleobase ring nitrogen (N-1 for pyrimidines and N-9 for purines) and the 1' carbon of the pentose sugar ring.

Non-standard nucleosides are also found in both RNA and DNA and usually arise from modification of the standard nucleosides within the DNA molecule or the primary (initial) RNA transcript. Transfer RNA (tRNA) molecules contain a particularly large number of modified nucleosides.

Source: Wikipedia.

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Related Questions

What kind of acid is in a molecule that carries a genetic information?

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Which organic molecule are nucleic acid?

DNA and RNA are nucleic acids.


What does 'deoxyribo ' stand for?

It means that the sugar in a molecule is deoxyribose.So, for example, deoxyribonucleic acid (DNA) means "the nucleic acid that has deoxyribose as the sugar component of every nucleotide in its molecule".


What type of biological molecule is DNA?

DNA is a nucleic acid, which is a type of biological molecule that carries genetic information in living organisms. It consists of a double helix structure made up of nucleotides containing a sugar, a phosphate group, and a nitrogenous base.


What is RNA an example of?

RNA is an example of a nucleic acid molecule that plays a key role in various biological processes, such as protein synthesis. It is made up of a single strand of nucleotides and can act as a messenger carrying genetic information from DNA to the ribosomes for protein production.


What is the molecule nicknamed the blueprint?

nucleic acid


What molecule is nitrogen in?

It's found in amino acid and nucleic acid


What is the building block molecule for nucleic acid?

nucleotides.


What organic molecule type is DNA?

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What molecule is made up of nucleic acid?

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The functional group that defines the 3' end of a nucleic acid molecule is the hydroxyl group (-OH).


Is RNA molecule a nucleic acid?

yes, it is. RNA stands of ribonucleic acid.