Nucleotides are the basic building blocks of DNA and RNA. They consist of a nitrogenous base, a 5-carbon sugar, and a phosphate group. There are four nitrogenous bases: adenine, guanine, cytosine, and thymine or uracil. In DNA, adenine pairs with thymine and cytosine pairs with guanine. In RNA, adenine pairs with uracil instead of thymine. The sequence of these nucleotide bases in nucleic acids determines an organism's traits and functions by encoding genetic information. Nucleotides come together to form the polymeric structures of DNA and RNA, which play essential roles in storing and transmitting genetic information.

1. BY JOYA KHAN

2. NUCLEOTIDE :The Building Blocks of Life
Nucleotide are the building blocks of DNA and RNA
.They consists of a sugar , a phosphate group and a
nitrogenous base . These bases encode genetic
information and pair up to form the genetic code
.The sequence of nucleotides in DNA and RNA
determines an organism traits and functions.

3. INTRODUCTION
Nucleotides are organic molecules composed of a nitrogenous
base, a pentose sugar and a phosphate. They serve
as monomeric units of the nucleic acid polymers –
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both
of which are essential biomolecules within all life-forms on Earth.
Nucleotides are obtained in the diet and are also synthesized
from common nutrients by the liver.
A biological system is a group of organs working together to
perform a common function. For example, the muscular system
is involved with movement, the skeletal system provides
protection and support, and the circulatory system delivers
nutrients and waste to and from the cells of the body.

4. STRUCTURE OF NUCLEOTIDE
The components of nucleotides are:
 Nitrogenous Base: Adenine, Thymine (only in DNA),
Guanine, and Cytosine.
 Five-Carbon Sugar: Deoxyribose (in DNA) or Ribose (in
RNA).
 Phosphate Group: A group of phosphorus and oxygen
atoms, linked to the 5' carbon of the sugar.
There are four types of nitrogenous bases found in
nucleotides:
1) Adenine (A): Adenine is one of the four DNA bases and
forms a base pair with Thymine (T) in DNA or with Uracil
(U) in RNA.
2)Thymine (T): Thymine is exclusive to DNA and pairs
with Adenine (A) through hydrogen bonding.

5. 3) Guanine (G): Guanine is one of the four DNA bases and
pairs with Cytosine (C) through hydrogen bonding in both
DNA and RNA.
4)Cytosine (C): Cytosine is one of the four DNA bases and
forms a base pair with Guanine (G) in both DNA and RNA.

6. DNA Vs RNA
Nucleotides of DNA and RNA:
Nucleotides are the building blocks of DNA (deoxyribonucleic
acid) and RNA (ribonucleic acid), essential molecules that play
vital roles in genetic information storage, transfer, and
expression in living organisms.
DNA Nucleotide:
DNA is composed of deoxyribonucleotides.
Each DNA nucleotide consists of three main components:
1)Deoxyribose sugar: A 5-carbon sugar molecule that
forms the backbone of the DNA strand.
2)Phosphate group: A phosphate molecule bonded to
the 5' carbon of the sugar.
.

7. 3)Nitrogenous bases: Adenine (A), Thymine (T), Cytosine
(C), and Guanine (G).
• Adenine pairs with Thymine (A-T) via two hydrogen bonds,
while Cytosine pairs with Guanine (C-G) via three
hydrogen bonds, forming the double-stranded DNA helix.
•DNA carries the genetic instructions necessary for the
development, functioning, growth, and reproduction of all
known living organisms.
RNA Nucleotide:
• RNA is composed of ribonucleotides.
•Each RNA nucleotide also consists of three primary
components:
1)Ribose sugar: A 5-carbon sugar molecule that
provides structural support to the RNA molecule.

8. 2)Phosphate group: A phosphate molecule attached to the
5' carbon of the sugar.
3)Nitrogenous bases: Adenine (A), Uracil (U), Cytosine (C),
and Guanine (G).
•Adenine pairs with Uracil (A-U) via two hydrogen bonds, and
Cytosine pairs with Guanine (C-G) via three hydrogen bonds,
allowing RNA to form various secondary structures.
• RNA functions in different types, such as messenger RNA
(mRNA), transfer RNA (tRNA), and ribosomal RNA
(rRNA), involved in protein synthesis and gene regulation.

9. DNA STRUCTURE
Double Helix Model (Watson –Crick Model)
The double helix model, proposed by James Watson and Francis
Crick in 1953, describes the three-dimensional structure of DNA.
It consists of two intertwined strands forming a twisted ladder-
like shape, with a sugar-phosphate backbone on the outside and
nitrogenous bases (adenine, thymine, cytosine, and guanine)
forming the rungs of the ladder on the inside. The bases pair
specifically: adenine with thymine, and cytosine with guanine,
held together by hydrogen bonds. This structure allows DNA to
store and transmit genetic information, and it serves as the
blueprint for the functioning and development of all living
organisms. The double helix model is one of the most important
discoveries in the history of molecular biology.

10. Base Pairing (A-T and G-C)
Base pairing refers to the specific pairing of nucleotide bases
in DNA. In short:
Adenine (A) pairs with Thymine (T) via two hydrogen bonds
(A-T).
Guanine (G) pairs with Cytosine (C) via three hydrogen
bonds (G-C).
These complementary base pairs are essential for the stability
and accurate replication of DNA, as well as for transmitting
genetic information from one generation to another.

11. RNA STRUCTURE
Single –Stranded Nature
The single-stranded nature of DNA or RNA means that it
consists of only one continuous chain of nucleotides.
Unlike the double-stranded DNA, which has two
complementary strands intertwined in a helix, a single-
stranded molecule is not paired with another
complementary strand.
In short, single-stranded DNA or RNA has just one
"backbone" consisting of sugar-phosphate units, and the
bases are exposed along this single chain. This
characteristic is critical for various biological processes,
such as transcription and translation, where single-
stranded molecules play essential roles in gene expression
and protein synthesis.

12. Various Types of RNA(mRNA,tRNA ,rRNA)
There are three main types of RNA:
1)Messenger RNA (mRNA): mRNA carries genetic information
from DNA in the nucleus to the ribosomes in the cytoplasm. It
serves as a template for protein synthesis during translation.
2)Transfer RNA (tRNA): tRNA brings amino acids to the
ribosomes during protein synthesis. It has an anticodon that
pairs with the mRNA codon, ensuring the correct sequence of
amino acids in the growing protein chain.
3)Ribosomal RNA (rRNA): rRNA is a structural component of
ribosomes, the cellular machinery responsible for protein
synthesis. It helps catalyze the formation of peptide bonds
between amino acids during translation.
Regenerate response

13. TRANSCRIPTION
Transcription is the process of synthesizing RNA from a
DNA template. In short:
Initiation: RNA polymerase binds to the promoter region
on the DNA.
Elongation: RNA polymerase reads the DNA template and
synthesizes a complementary RNA strand.
Termination: Transcription stops when RNA polymerase
reaches the termination signal on the DNA.
Result: The newly formed RNA molecule, called mRNA,
carries genetic information from the DNA to the ribosomes
for protein synthesis.

14. TRANSLATION
"Translation in short" refers to providing a concise or brief
version of a text or content in another language. It involves
summarizing the main points or essence of the original material
while preserving its meaning and intent.
PCR is a common tool used in medical and biological research
labs. It is used in the early stages of processing DNA for
sequencing?, for detecting the presence or absence of a gene to
help identify pathogens? during infection, and when
generating forensic DNA profiles from tiny samples of DNA.
PCR (POLYMERASE CHAIN
REACTION)

15. CONCLUSION
From the above discussion it has been concluded nucleotide
are the building blocks of RNA and DNA , This means that
nucleotide act as a monomers units large no. of monomers
units polymerize to form a polymer (RNA and DNA ) RNA
and DNA are a genetic material that inherites from one
generation to other i.e.(parents to offspring )