What is the composition of nucleoside?a)a sugar + a phosphateb)a base + a sugarc)a base + a phosphated)a base + a sugar + phosphateCorrect answer is option 'B'. Can you explain this answer?

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Answer

Nucleosides (bottom) are made of a nitrogenous base, usually either a purine or pyrimidine, and a five-carbon carbohydrate ribose. A nucleotide is simply a nucleoside with an additional phosphate group or groups (blue); polynucleotides containing the carbohydrate ribose are known as ribonucleotide or RNA.
Nucleoside, a structural subunit of nucleic acids, the heredity-controlling components of all living cells, consisting of a molecule of sugar linked to a nitrogen-containing organic ring compound. In the most important nucleosides, the sugar is either ribose or deoxyribose, and the nitrogen-containing compound is either a pyrimidine (cytosine, thymine, or uracil) or a purine (adenine or guanine).
that is nucleoside are composed of a base + a sugar

Answer

The Composition of Nucleoside

Nucleosides are organic molecules that play a crucial role in the structure and function of DNA and RNA. They consist of two main components: a nitrogenous base and a sugar molecule. Let's explore the composition of a nucleoside in detail:

1. Nitrogenous Base:
The nitrogenous base is a key component of a nucleoside. It is a heterocyclic organic compound that contains nitrogen atoms in its structure. There are five commonly occurring nitrogenous bases in nucleosides:

- Adenine (A): It is a purine base consisting of two fused rings.
- Guanine (G): Also a purine base, it is structurally similar to adenine.
- Cytosine (C): It is a pyrimidine base that contains a single ring.
- Thymine (T): Another pyrimidine base that is found specifically in DNA.
- Uracil (U): This pyrimidine base is found in RNA instead of thymine.

2. Sugar Molecule:
The sugar molecule in a nucleoside is a pentose sugar, which means it consists of five carbon atoms. There are two types of pentose sugars found in nucleosides:

- Deoxyribose: It is a modified form of ribose sugar found in DNA. The only difference between ribose and deoxyribose is the absence of an oxygen atom on the 2' carbon of the sugar molecule.
- Ribose: This sugar molecule is found in RNA.

3. Bonding:
The nitrogenous base and sugar molecule in a nucleoside are connected through a β-glycosidic bond. This bond forms between the 1' carbon of the sugar molecule and the nitrogenous base.

Examples:
Here are a few examples of nucleosides:

- Adenosine: It consists of the base adenine and the sugar ribose.
- Deoxyadenosine: It is similar to adenosine but contains deoxyribose instead of ribose.
- Cytidine: It consists of the base cytosine and the sugar ribose.

Summary:
In summary, a nucleoside is composed of a nitrogenous base and a sugar molecule. The nitrogenous base can be either a purine (adenine or guanine) or a pyrimidine (cytosine, thymine, or uracil). The sugar molecule is a pentose sugar, which can be either ribose (found in RNA) or deoxyribose (found in DNA). These components are connected through a β-glycosidic bond, forming a nucleoside.

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