Monomers of DNA and RNA | Their Chemistry & Shape

Monomers are single-unit molecules that can bind to each other to form long chains or polymers.

The monomers of DNA and RNA are

1. Ribose sugar molecule
2. Deoxyribose sugar molecule
3. Adenine
4. Guanine
5. Thymine
6. Cytosine
7. Uracil

As the name indicates, DNA (deoxyribonucleic acids) and RNA (ribonucleic acids) have similar structures and are made of similar monomers.

They are made of nuclear bases and carbohydrate monomers.

These nucleic acids, DNA and RNA, are found in all living cells, including viruses, and are believed to have come to Earth from space (as per NASA).

Most organic compounds, like carbohydrates, amino acids, nucleic acids, etc., can be isolated as monomers.

Monomers of nucleic acid DNA and RNA

Monomers of DNA

DNA is present as a double-stranded structure with two strands aligned in a helix.

• DNA has five monomers, of which one is a carbohydrate monomer, while the remaining four are nuclear bases.

• The carbohydrate monomer is a five-carbon sugar, namely deoxyribose sugar.

The four nuclear bases include two purine bases, namely

1. Adenine
2. Guanine

and two pyrimidine bases, namely

1. Thymine
2. Cytosine

Monomers of RNA

• Like DNA, RNA also has a single carbohydrate monomer, namely ribose sugar, a five-carbon sugar.

Then there are four nuclear bases, of which two are purine bases like

a) Adenine

b) Guanine

and two pyrimidine bases as

C) Uracil

d) Cytosine.

• So the purine bases are the same monomers in both the DNA and RNA but the pyrimidine bases are different between these two nucleic acids.

• There is uracil instead of thymine in the RNA strand.

• In both these molecules, the sugar monomers are held together to form a long strand by a phosphodiester bond.

• At the same time, the nuclear bases are bound to the carbohydrate monomer.

• The DNA molecule is a double-strand structure, while the RNA is a single-strand structure.

• The double-strand structure of DNA is possible due to the hydrogen bonds between the nuclear bases of both chains.

• DNA is the genetic material and is more stable than RNA.

• DNA resides in the nucleus as a double-strand structure and a single-strand structure in mitochondria.

• RNA is a less durable genetic material and is present mainly in the cytoplasm of the cell.

Frequently asked questions and answers

References:

• NASA Researchers: DNA Building Blocks Can Be Made in Space