An Introduction to Nucleic Acid
Much like you would record your favorite songs on a tape in the 90s, so is our genetic information encoded in our cells, in the form of RNA and DNA. These are made of polymers of repeating units, with acidic properties. The term “nucleic acid” is used to describe these large molecules in our cells that hold so much vital information about us, our lineage, and our genetic setup.
Thus, nucleic acids are defined as large macromolecules that store, encode and transmit genetic data from one generation to another.
Let us find out more about nucleic acids and their structure and properties.
Nucleic Acids Structure
These vital macromolecules are typically made of oxygen, nitrogen, hydrogen, phosphorus, and most importantly, carbon. They are long-chain polymers that consist of monomeric units called nucleotides. Each nucleotide comprises a phosphate group, a 5-carbon sugar, and a specific nitrogen base.
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In a nucleotide, if the sugar happens to be a ribose, then the polymer is called ribonucleic acid or RNA. Likewise, if the sugar is deoxyribose, it is called deoxyribonucleic acid or DNA. These are the most vital of all biomolecules present in living organisms. Found abundantly in all living organisms, they help encode, create and transmit the codex of genetic information of every cell in every organism. Furthermore, this encoded information is transmitted through the nucleic acid structure of DNA and RNA.
A string of nucleotides is bonded together to form the helical backbones of these nucleic acids. Typically, DNA consists of two such backbones while RNA consists of one. These further assemble into chains of base pairs of nucleobases. Nucleobases are prominent of four types: adenine, guanine, cytosine, uracil, and thymine. Note that uracil is found only in RNA while, thymine is present only in DNA.
Through a combination of several processes that include protein synthesis using amino acids, the sequences of these nucleobases allow nucleic acids like DNA to store and encode the body's genetic information.
Pop Quiz 1
Which of these is a sugar group present in DNA?
Ribose
Thymine
Deoxyribose
Uracil
Nucleic Acids Types
As we mentioned earlier, there are two major types of nucleic acids commonly found in living organisms. These are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the primary genetic material that is the source of all genetic information in living organisms. From the smallest unicellular bacteria to multicellular animals such as elephants and human beings, each of these contains DNA in their cells. DNA is also present in the nuclei of eukaryotes as well as in plants, chloroplast, and mitochondria.
Prokaryotic organisms, however, do not have their DNA enclosed in a membranous coat. In such organisms, the DNA is found freely floating in the cytoplasm.
The genetic machinery of each cell, in its entirety, is known as a genome. The study of genomes, on the other hand, is known as genomics.
Activity: Find out from the Internet how each DNA or RNA strand in a cell is packed. Discuss it with your friends and teacher.
DNA Nucleic Acid
In combination with histone proteins, DNA forms a chemical complex called chromatin in the cells of eukaryotic organisms.
This, however, does not occur in prokaryotes.
Each chromosome of a living organism is a repository of thousands of hundreds of genes, dictating the organism’s identity, behavior, habit, and other functions.
Most genes contain the information that can code for protein products in the body. Some of these can also code for RNA products.
All cellular activity in cells is controlled by DNA.
Structure of DNA
DNA consists of a double helix backbone made of two chains of polynucleotides.
This double helix consists of two DNA strands, running parallel to each other.
There exist hydrogen bonds between the helices, while the bases are contained in bundles within the helix.
DNA is negatively charged, owing to the presence of phosphate groups.
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The chemical composition of DNA consists of phosphoric acid, cyclic nitrogen bases, and pentose sugar.
β-D-2-deoxyribose is the sugar molecule present in DNA molecules.
The cyclic nitrogen bases found in DNA are adenine, guanine, thymine, and cytosine.
These bases play a key role in the storage and transmission of genetic data, from the parent generation to the next.
Structure of RNA
RNA, in eukaryotic cells, mostly participates in the synthesis of proteins and translation and transcription of genetic code. During transcription and protein synthesis, DNA molecules use an intermediate messenger RNA, also called mRNA to communicate with the entire cellular machinery, without leaving its place of origin. There are several other types of RNA that participate in protein synthesis. These are the microRNA, tRNA, and rRNA. In addition, the RNA is single-stranded and is often found to be in a folded state.
Similar to DNA, RNA molecules also contain phosphoric acid, heterocyclic nitrogen bases, and a pentose sugar group.
The heterocyclic bases found in RNA are guanine, adenine, cytosine, and uracil. Unlike DNA, the sugar molecule present in RNA is a β-D-ribose, attached to phosphate groups.
Based on the functions they perform, RNA is of four different types. These are:
Messenger RNA: During the process of transcription, an RNA transcript is formed, which is also known as messenger RNA. The DNA uses this to communicate with all the other cells.
Micro RNA: Micro RNA is the smallest of all four types of RNA. It plays a very crucial role in gene expression and regulation.
Transfer RNA: Transfer RNAs participate in the translation of the mRNA transcript produced during protein synthesis.
Ribosomal RNA: One of the most essential RNAs known, these are an integral component of ribosomes and help produce proteins in the body and our cells.
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Nucleic Acids Function
The DNA never leaves its place of origin but uses the RNA to act as an intermediate to communicate with the rest of the cell.
This intermediate mRNA enters the nucleus of the cell during the synthesis of proteins, and bonds with one of the DNA strands.
The sequence of nitrogen bases in DNA is oppositeNucleic acids, mainly DNA and RNA, play an essential role in the bodies of living organisms. The functions performed by these are as follows:
Nucleic acids help synthesize proteins in the body.
RNA is an especially important factor in the manufacturing of proteins.
to that of RNA, as they are complementary. This process is called transcription.
For instance, if an RNA strand reads UUCCGGAA, then the DNA strand would read AAGGCCTT.
Furthermore, the messenger RNA helps to transmit the code from the nucleus of the cell to the ribosomes. These are then assembled to form proteins.
On reaching the ribosomes, the mRNA does not immediately set out to form proteins.
In this step, the transferred RNA, also called the tRNA attaches itself to the mRNA, to translate the information carried by the mRNA into a readable form.
This is done with opposite base pairings and in sets of three, also called codons.
Thus each three-letter set can be a possible codon, encoding vital instructions and information.
This correspondence is also known as the genetic code. It is present uniformly throughout all living organisms.
The loss of nucleic acids, or DNA in cells, can be the cause for mutation and a variety of other diseases.
DNA is a vital part of the fingerprinting method employed by forensic experts. Often used in matters of paternal disputes as well as criminal cases, the study of DNA is among the most flourishing fields of research, including evolution, anthropology, natural history, and epidemiology.
Nucleic Acids Test
A nucleic acid test or NAT is a burgeoning technique used in medical science as well as other fields of molecular biology and research, to detect strains of unknown bacteria, viruses, and other microbes. In this test, a particular sequence of nucleic acids is investigated and detected. This helps to identify or eliminate various strains of viruses and bacteria, or other pathogens in the blood. They are unique to the field of pathology, in the sense that, unlike most tests that detect antibodies or antigens, the NAT focuses more on the genetic components of the microbes.
This was a brief overview of nucleic acids, their structure, and their function. To learn more about DNA and its many functions, as well as other key topics in molecular biology, stay tuned to our live demo classes, free PDF study material, and reference notes. Download the Vedantu app today for easier access.
Molecular Biology
Molecular biology is the study of biological and chemical changes in and between cells. The field of molecular biology is very much focused on the nucleic acids and other macro and micro molecules that affect life processes. The living things on earth are also made up of complex chemicals just how the non-living things are. The molecular biologist works on figuring out how these chemicals affect the way of life and how it functions. There are so many complex chemicals involved in biology itself, although molecular biologists focus on the RNA and DNA, proteins and genes in specific. Not only that, but they also learn and understand the structure of the molecule and how it works, which in turn helps other biologists that work on engineering that chemically like drug makers or genetic engineers.
The two other related fields to molecular biology are genetics and biochemistry. Even though each of them is concerned with a specific study to focus on, they are still related and often have intersecting topics.
Biochemistry
Biochemistry is the study of chemicals in organisms. It focuses more on the molecules and nucleic acid rather than the proteins. Additionally, biochemistry also involves the study of chemicals when present in large quantities.
Genetics
Genetics is all about the study of heredity, the genes’ structure, and how it changes in the species. To understand the hereditary traits, it has to be studied on a large scale, almost on the population level, thus making it a larger scale field than molecular biology.
The Differences between DNA and RNA
Types of DNA
The DNA can be classified into mitochondrial DNA and nuclear DNA based on its location, as some plants and animals store their DNA in the nucleus of a cell whereas, in some, it is stored in the mitochondria.
Mitochondrial DNA
It is located in the mitochondria of a cell.
The mitochondrial DNA is haploid, which means it's inherited only from the mother.
Nuclear DNA
It is located in the nucleus of a cell.
The nuclear DNA is diploid, which means it's inherited from both parents.
Supercoiling
The process of DNA being twisted in like a rope is known as DNA supercoiling. Based on the direction of the coiling, it is further classified into positive and negative supercoiling. The DNA twisted in the direction of the helix is termed positive supercoiling and vice versa is termed negative supercoiling.
Genetic Engineering
Genetic engineering is also termed genetic manipulation or modification. Genetic engineering is changing the genetics of an organism using the help of biotechnology. The new DNA received is used to make genetic modifications in the species or create a new species altogether. Thus, the organism or a species that is obtained from such genetic modification is known as a Genetically modified organism(GMO).
Till today, genetic engineering has been used in various fields including agriculture and biotechnology. The genetically modified crops have economically supported farmers. Although the effect of such crops on crops on the health of a human being is questionable.
Applications of Genetic Engineering
Genetic engineering is a mode of research on various genes and species for scientists. With the help of extracting a certain gene from an organism or plant species and storing it in a bacteria for a long time, research can be done for a very long time.
From gene therapy to the making of drugs and testing it, genetic engineering has been helpful in the field of medicine. Vaccines are a very good example of it.
Agriculture is by far the most benefited by genetic engineering. The various modifications done in crops have helped the farmers economically as well as to grow much healthier crops that do not get affected by certain diseases.
Apart from that, genetic engineering is also used in the conservation of plant and animal species.
In industrial microbiology, genetic engineering is used to produce certain kinds of enzymes.
FAQs on Nucleic Acids
1. What are the main components of nucleic acids?
Ans. A nucleic acid is a long-chain polymer made of monomeric units called nucleotides. A nucleotide, in turn, consists of three primary components. These are a phosphate group, a sugar molecule bonded to the phosphate group and a cyclic nitrogenous base. These nitrogenous bases can be of five types, namely adenosine, thymine, uracil, cytosine and uracil.
2. What is a nucleic acid?
Ans. Nucleic acids can be defined as large macromolecules that store, encode and transmit genetic information from one generation to another. These vital macromolecules are typically made of oxygen, nitrogen, hydrogen, phosphorus and most importantly, carbon. They are long-chain polymers that consist of monomeric units called nucleotides.
3. Which nucleic acids are present in viruses?
Ans. Viruses, usually have either DNA or RNA as their genetic material. These can be double-stranded or single-stranded.
4. What are the functions of nucleic acids?
Ans. Nucleic acids help synthesise proteins in the body. The RNA is an especially important factor in the synthesis of proteins. The DNA never leaves its place of origin but uses the RNA to act as an intermediate to communicate with the rest of the cell. DNA is a vital component of the fingerprinting method used by forensic experts.