Nucleic Acid: Structure & Function |UPSC Notes

Nucleic acid, in essence, is any part of a living thing. These crucial biomolecules carry and transmit genetic information, and this makes life possible. From plants, and animals, to microorganisms, nucleic acids have led to the blueprint that describes their biological function and characteristics. In molecular biology, nucleic acid is of central importance, explaining how characters are inherited and then expressed.

• DNA stores the genetic information in the sequence of nucleotides
• RNA transfers the genetic information for protein synthesis
• Both DNA and RNA are made up of repeating units called nucleotides.
• Nucleic acids are present in all living cells.

GS Paper	GS Paper III
Topics for UPSC Prelims	Basic concepts of Nucleic Acids (DNA, RNA), Structure of DNA and RNA, Functions of nucleic acids in cell biology, Differences between DNA and RNA
Topics for UPSC Mains	Role of Nucleic Acids in genetics and heredity, Applications of genetic engineering in biotechnology and agriculture, Ethical concerns related to genetic modification and CRISPR technology

Structure of Nucleic Acids

Nucleic acid is a polymer of monomers called nucleotides. A nucleotide consists of three constituents: a nitrogenous base, a sugar molecule, and a phosphate group. These nucleotides form long chains to give the DNA or RNA structure. A particular sequence of nucleotides in the nucleic acid decides what kind of information that particular nucleic acid contains.

These are adenine (A), thymine (T), cytosine (C), and guanine (G). Thymine is substituted for uracil in RNA. The arrangement of these bases forms the genetic code that instructs the synthesis of proteins, the building blocks of life.

DNA vs RNA – Difference Between Nucleic Acids

Feature	DNA (Deoxyribonucleic Acid)	RNA (Ribonucleic Acid)
Full Form	Deoxyribonucleic Acid	Ribonucleic Acid
Sugar Component	Deoxyribose	Ribose
Structure	Double-stranded helix	Single-stranded
Nitrogenous Bases	Adenine (A), Thymine (T), Cytosine (C), Guanine (G)	Adenine (A), Uracil (U), Cytosine (C), Guanine (G)
Location	Mostly in the nucleus of cells, some in mitochondria	Found in the nucleus, cytoplasm, and ribosomes
Stability	More stable, less reactive	Less stable, more reactive
Function	Stores and transmits genetic information	Involved in protein synthesis and gene expression
Types	Only one type of DNA	Three types: mRNA (messenger RNA), tRNA (transfer RNA), rRNA (ribosomal RNA)
Base Pairing	Pairs with U, C pairs with G	A pairs with U, C pairs with G
Length	Pairs with T, C pairs with G	Generally shorter and smaller in size

Functions of Nucleic Acids in Cells

The main role of nucleic acids in cells is the storage and transfer and then the expression of genetic information. DNA contains the instructions needed for the growth, reproduction, and functioning of an organism. While a cell divides, its DNA replicates itself so that when it finally splits into two new cells, they’ll each have the same genetic information. RNA then assists in translating the information into proteins, which carry out most cellular functions.

Genetic Information Storage

Nucleic acids, primarily DNA, carry genetic information within a cell that determines its structures, functions, and reproduction. They are templates for protein synthesis that determine cell structure, function, and the time of replication. This particular genetic code ensures that each trait is passed from parent generation to offspring with perfect accuracy.

Protein Synthesis Regulation

RNA is a crucial effector in protein synthesis, as it carries the genetic information from DNA into ribosomes, which then make proteins according to the code carried in. In the case of mRNA, rRNA, and tRNA, such an accurate shape is ensured during their formation.

Gene Expression Control

Nucleic acids activate or deactivate the genes within the cell so that the expression of genes is controlled. This will make it possible for cells to have different functions under different conditions and express only proteins supposed to be produced at particular periods.

Energy Transfer and Storage

Some of the nucleic acids act as energy carriers in the cell, such as ATP (adenosine triphosphate), which stores and transfers energy used for metabolism, signaling, and muscle contraction.

Signal Transduction and Communication

Nucleic acids are involved in signal transduction pathways, and they play a role in the responsiveness of cells to external stimuli by which the chemical environment may be sensed and acted upon appropriately. They carry out their signaling roles by transmitting signals that regulate cellular activities and growth as well as differentiation. 

Role of Nucleic Acid in Genetic Engineering

Nucleic acid is considered a crucial factor in genetic engineering and biotechnology. Indeed, through DNA modification, it has become possible to alter the genetic makeup of organisms. Scientists have thus been able to make genetically altered crops, bacteria, and indeed therapies for genetic diseases. 

Genetic Information Manipulation

Nucleic acids are at the core of genetic engineering, where DNA sequences are manipulated to alter genetic characteristics. Altering specified genes can create an organism with desired characteristics, increase crop yield, or find new medical applications. Such genetic alteration shall influence greatly biotechnology and agricultural practices.

Recombinant DNA Technology

In genetic engineering, nucleic acids are used to create recombinant DNA by combining genetic material from different sources. This way, contributions of genes in organisms may end up producing proteins or characteristics not originally found in the organism, thereby leading to revolutionary changes in medicine, agriculture, and industry.

Gene Cloning

Nucleic Acids Nucleic acids are the main molecules in gene cloning process that aids in the generation of many copies of a particular gene or DNA sequence. Multiple copies of the gene can be produced through the insertion of DNA fragments into vectors, allowing extensive study and manipulation for developing new therapies, genetically modified organisms, and innovative biotechnological applications.

Development of Gene Therapy Techniques

Gene therapy techniques were developed and very much essential for the replacement or repair of defective genes in patients. Using engineered nucleic acids, scientists can introduce functional genes into cells, hoping to treat genetic diseases at the root cause, promising excellent medical breakthroughs.

Applications of Nucleic Acids in Health and Disease

The structures and functionalities of nucleic acids are closely related to health. Genetic diseases, such as cystic fibrosis and sickle cell anemia, may result from mutations of DNA. When one knows the nature of nucleic acid, they can identify and correct those mutations, holding hope for potential treatments or cures for them.

• RNA vaccines have become the new waves of fighting illnesses like COVID-19. These vaccines will use the information contained in the RNA, which instructs cells to make proteins triggering an immune response against the virus, thereby offering protection.
• Genetic variations in DNA cause different diseases.
• New therapies could be treated through RNA-based medical interventions.
• DNA Analysis is applied in diagnostics and personalized medicine.

Role of Nucleic Acid in Evolution

New traits are developed through the succession of generations, which brings variation in DNA sequences over generations. DNA among species can trace evolutionary relationships and the history of the evolution of life on Earth that is spread over billions of years.

• Source of Genetic Variation: Nucleic acids produce genetic variations through mutations. These variations cause the evolution process as species ensure adaptation to different new environments.
• Hereditary Information Transmission: DNA in the case of nucleic acids ensures the transfer of the genetic information from one generation to another. This continuity provides some of the effects brought about by evolution.
• Natural Selection Foundation: Mutation in nucleic acids is a primary raw material for which natural selection acts. Favorable changes improve survival and reproduction, and little by little, an evolutionary change takes place in populations.
• Species Divergence Trigger: Nucleic acids trigger divergence of species through the accumulation of genetic differences. These differences between generations create variations that make populations evolve into different species, thus adding more diversity in nature.

Conclusion

In simple terms, nucleic acid is the foundation of life, which controls the genetic blueprint of all living organisms. Storing genetic information in DNA and assistance for protein synthesis by RNA makes nucleic acids fundamental biological functions. Beyond cellular scope, it impacts biotechnology and medicine and influences evolutionary biology. 

Nucleic Acid UPSC Notes

1. Nucleic acids are essential biomolecules that store and transfer genetic information, found in all living organisms. 2. There are two main types of nucleic acids: DNA, which stores genetic information, and RNA, which assists in protein synthesis. 3. DNA is double-stranded, contains thymine, and is stable, while RNA is single-stranded, contains uracil, and transmits genetic information. 4. Nucleotides, the building blocks of nucleic acids, consist of a nitrogenous base, sugar molecule, and phosphate group. 5. Nucleic acids play a vital role in cell replication, gene expression, and protein synthesis through DNA and RNA functions. 6. Nucleic acids are central to genetic engineering, biotechnology, and therapies like mRNA vaccines used in modern medicine.

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