What is DNA?
“DNA is a group of molecules that is responsible for carrying and transmitting the hereditary
materials or the genetic instructions from parents to off springs.”
Full-Form of DNA
DNA is known as Deoxyribonucleic Acid. It is an organic compound that has a unique molecular
structure. It is found in all prokaryotic cells and eukaryotic cells.
Who Discovered DNA?
DNA was first recognized and identified by the Swiss biologist, Johannes Friedrich
Miescher in 1869 during his research on white blood cells.
The double helix structure of a DNA molecule was later discovered through the experimental
data by James Watson and Francis Crick. Finally, it was proved that DNA is responsible for
storing the genetic information in living organisms.
Structure of DNA
The DNA molecule is composed of units called nucleotides, and each nucleotide is
composed of three different components, such as sugar, phosphate groups and nitrogen
The basic building blocks of DNA are nucleotides, which are composed of a sugar group, a
phosphate group, and a nitrogen base.
The sugar and phosphate groups link the nucleotides together to form each strand of DNA.
These 4 Nitrogenous bases pair together in the following way:
These base pairs are essential for the DNA’s double helix structure, which resembles a
1. Adenine (A)
2. Thymine (T)
3. Guanine (G)
4. Cytosine (C) are four types of nitrogen bases.
1. A with T
2. C with G.
Among the three components of DNA structure, sugar is the one which forms the backbone of the DNA
molecule. It is also called deoxyribose.
The nitrogenous bases of the opposite strands form hydrogen bonds, forming a ladder-like structure.
The DNA molecule consists of 4 nitrogen bases, namely adenine (A), thymine (T), cytosine (C) and
Guanine (G) which ultimately forms the structure of a nucleotide.
The A and G are purines and the C and T are pyrimidines.
The two strands of DNA run in opposite directions.
These strands are held together by the hydrogen bond that is present between the two complementary
The strands are helically twisted, where each strand forms a right-handed coil and ten nucleotides make up
a single turn.
The pitch of each helix is 3.4 nm. Hence, the distance between two consecutive base pairs (i.e., hydrogen-
bonded bases of the opposite strands) is 0.34 nm.
DNA is the genetic material which carries all the hereditary information.
Apart from storing genetic information, DNA is involved in:
Replication process: Transferring the genetic information from one cell to its daughters and from one
generation to the next and equal distribution of DNA during the cell division
Mutations: The changes which occur in the DNA sequences
What is RNA ?
RNA is a ribonucleic acid that helps in the synthesis of proteins in our body.
This nucleic acid is responsible for the production of new cells in the human body.
It is usually obtained from the DNA molecule.
RNA resembles the same as that of DNA, the only difference being that it has a single
strand unlike the DNA which has two strands and it consists of an only single ribose
sugar molecule in it.
Hence is the name Ribonucleic acid.
RNA is also referred to as an enzyme as it helps in the process of chemical reactions in
Basic Structure of RNA
The basic structure of RNA is shown in the figure below-
The ribonucleic acid has all the components same to that of the DNA with only
2 main differences within it.
RNA has the same nitrogen bases called the adenine, Guanine, Cytosine as that
of the DNA except for the Thymine which is replaced by the uracil.
Adenine and uracil are considered as the major building blocks of RNA and
both of them form base-pair with the help of 2 hydrogen bonds.
RNA resembles a hairpin structure and like the nucleotides in DNA,
nucleotides are formed in this ribonucleic material(RNA).
Nucleosides are nothing but the phosphate groups which sometimes also helps
in the production of nucleotides in the DNA.
There are various types of RNA, out which most
well-known and most commonly studied in the
human body are :
1. tRNA – Transfer RNA
The transfer RNA is held responsible for
choosing the correct protein or the amino
acids required by the body in-turn helping the
It is located at the endpoints of each amino
This is also called as soluble RNA and it forms
a link between the messenger RNA and the
2. rRNA-Ribosomal RNA
The rRNA is the component of the ribosome
and are located within the in the cytoplasm of
a cell, where ribosomes are found.
In all living cells, the ribosomal RNA plays a
fundamental role in the synthesis
and translation of mRNA into proteins.
The rRNA is mainly composed of cellular
RNA and are the most predominant RNA
within the cells of all living beings
3. mRNA – Messenger RNA
This type of RNA functions by
transferring the genetic material into the
ribosomes and pass the instructions
about the type of proteins, required by
the body cells.
Based on the functions, these types of
RNA is called the messenger RNA.
Therefore, the mRNA plays a vital role
in the process of transcription or during
the protein synthesis process.
Functions of RNA
The ribonucleic acid – RNA, which are mainly composed of nucleic acids,
are involved in a variety of functions within the cell and are found in all
living organisms including bacteria, viruses, plants, and animals.
These nucleic acid functions as a structural molecule in cell organelles and
are also involved in the catalysis of biochemical reactions.
The different types of RNA are involved in various cellular process.
The primary functions of RNA:
Facilitate the translation of DNA into proteins
Functions as an adapter molecule in protein synthesis
Serves as a messenger between the DNA and the ribosomes.
They are the carrier of genetic information in all living cells
Promotes the ribosomes to choose the right amino acid which is required in
building up of new proteins in the body.
What are proteins?
Proteins are made up of many building blocks, known as amino
Our body needs dietary protein to supply amino acids for the growth
and maintenance of our cells and tissues.
Our dietary protein requirement changes throughout life.
The European Food Safety Authority (EFSA) recommends adults
consume at least 0.83 g of protein per kg body weight per day (e.g.
58 g/day for a 70 kg adult).
Plant and animal-based proteins vary in their quality and
digestibility, but this is not usually a concern for most people if their
total protein meets their needs.
We should aim to consume protein from a variety of sources that
benefits both our health and the planets.
What are proteins made of?
Proteins are made up of many different amino acids linked together.
There are twenty different of these amino acid building blocks commonly found in plants
A typical protein is made up of 300 or more amino acids and the specific number and
sequence of amino acids are unique to each protein.
Rather like the alphabet, the amino acid 'letters' can be arranged in millions of different ways
to create 'words' and an entire protein 'language’.
Depending on the number and sequence of amino acids, the resulting protein will fold into a
Amino acids are classified as either essential or non-essential.
As the name suggests, essential amino acids cannot be produced by the body and therefore
must come from our diet.
Whereas, non-essential amino acids can be produced by the body and therefore do not need
to come from the diet.
What do proteins do for the body?
Our bodies are made up of thousands of different proteins, each with a specific
They make up the structural components of our cells and tissues as well as
many enzymes, hormones and the active proteins secreted from immune cells .
These body proteins are continually being repaired and replaced throughout our
This process (known as ‘protein synthesis’) requires a continuous supply of amino
Although some amino acids can be recycled from the breakdown of old body
proteins, this process is imperfect.
This means we must eat dietary protein to keep up with our body’s amino acid
As protein is essential for cell and tissue growth, adequate intake of protein is
particularly important during periods of rapid growth or increased demand, such
as childhood, adolescence, pregnancy, and breastfeeding.
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