DNA: Structure, Function and Discovery


The organic materials found in all organisms in the form of DNA or RNA are called nucleic acids. These nucleic acids are created through the combination of sugar molecules, phosphate groups, and nitrogenous bases joined by various bonds in a sequence. Our body’s basic genetic composition is defined by the structure of our DNA. It actually describes the genetic composition of almost all species on Earth.

Continue reading to learn about the meaning, structure, function, discovery, and diagram of DNA in full.

Describe About DNA.

“The genetic instructions or hereditary materials are carried and transmitted from parents to offspring by a group of molecules called DNA.”

This also holds true for viruses, since the genetic material of most of these creatures is made up of either DNA or RNA. For example, the genetic material of some viruses might be RNA, but the genetic material of other viruses might be DNA. The RNA that makes up the Human Immunodeficiency Virus (HIV) is transformed into DNA once it has bonded to the host cell.

In addition to ensuring that all living things inherit their genetic makeup, DNA is essential for the synthesis of proteins. The DNA found in each nucleus of a eukaryotic creature is known as nuclear DNA. It codes for most of the genomes of the organisms; the remainder is handled by the DNA of the plastids and mitochondria.

Mitochondrial DNA is the name given to the DNA found inside the cell’s mitochondria. It is passed down from the mother to her offspring. The human mitochondrial DNA consists of about 16,000 base pairs. In a similar vein, plastids are vital to photosynthesis and have their own DNA.

What is the Full-Form of DNA

We refer to Deoxyribonucleic Acid as DNA. It is an organic substance with a distinct molecular make-up. Every prokaryotic and every eukaryotic cell has it.

DNA Types

There are three different DNA types:

  • The right-handed double helix of A-DNA resembles that of B-DNA. Dehydrated DNA adopts an A form that shields it from harsh environments like desiccation. Additionally, DNA loses its solvent when bound by proteins, taking on the A form.
  • B-DNA: This is a right-handed helix and the most prevalent DNA shape. Under normal physiological settings, most DNA has a B type shape.
  • Z-DNA: The double helix of Z-DNA winds in a zigzag manner to the left, making it a left-handed DNA. Alexander Rich and Andres Wang made the discovery. It is thought to have some function in gene regulation because it is located before a gene’s start point.

Who Discovered DNA?

The Swiss biologist Johannes Friedrich Miescher discovered and named DNA for the first time in 1869 while studying white blood cells.

Eventually, using the experimental data collected by James Watson and Francis Crick, the double helix structure of a DNA molecule was identified. It has finally been established that genetic information in living things is stored in DNA.

DNA Diagram

DNA Diagram
DNA Diagram

DNA Structure

You can visualize the DNA structure as a twisted ladder. The structure depicted in the above image is referred to as a double helix. It is a nucleic acid, and nucleotides are the building blocks of all nucleic acids. Nucleotides, the building blocks of the DNA molecule, are made up of three distinct components: sugar, phosphate groups, and nitrogen bases.

Nucleotides, which are made up of a sugar group, a phosphate group, and a nitrogen base, are the fundamental units of DNA. Each strand of DNA is formed by the joining of the nucleotides by the sugar and phosphate groups. There exist four distinct types of nitrogen bases: adenine (A), thymine (T), guanine (G), and cytosine (C).

The pairings of these four nitrogenous bases are as follows: A with T and C with G. The DNA’s double helix structure, which resembles a twisted ladder, depends on these base pairs.

The instructions included in DNA, or the genetic code, are determined by the arrangement of nitrogenous bases.

The skeleton of the DNA molecule is made up of sugar, one of the three constituents of DNA structure. Another name for it is deoxyribose. The opposing strands’ nitrogenous bases combine to generate hydrogen bonds, creating a structure resembling a ladder.

The four nitrogen bases that make up the DNA molecule are adenine (A), thymine (T), cytosine (C), and guanine (G). Together, these bases create the structure of a nucleotide. Purines are A and G, and pyrimidines are C and T.

The directions in which the two DNA strands run are opposing. The hydrogen connection that exists between the two complimentary bases holds these strands together. A single turn of the helically twisted strands consists of ten nucleotides, with each strand forming a right-handed coil.

Every helix has a pitch of 3.4 nm. Therefore, 0.34 nm separates two successive base pairs, or the hydrogen-bonded bases of the opposing strands.

Chromosomes are formed as DNA coils up, and each chromosome contains a single DNA molecule. In the nucleus of each cell, humans have approximately 23 pairs of chromosomes. Additionally, DNA is crucial to the process of cell division.

The Chargaff Rule

The biochemist Erwin Chargaff found that there were equal amounts of nitrogenous bases in the DNA. Whereas the amount of C equals G, the amount of A equals T.

A=T; C=G

Put otherwise, the purine and pyrimidine base ratio in any organism’s DNA should be 1:1.

Replication of DNA

One crucial activity that takes place during cell division is DNA replication. DNA copies itself during a process known as semi-conservative replication.

There are three phases of DNA replication:

Step 1: Commencement
The origin of replication is the location where DNA replication starts. The DNA helicase keeps the two DNA strands apart. The replication fork is formed by this.

Step 2: Elongation
After reading the nucleotides on the template strand, DNA polymerase III adds complimentary nucleotides one after the other to create a new strand. It will add a thymine to the complimentary strand, for example, if it reads an adenine on the template strand.

Gaps appear between the strands as nucleotides are added to the trailing strand. We refer to these spaces as Okazaki fragments. Ligase fills in these holes or nicks.

Step 3: Dismissal
The replication process is stopped by the termination sequence that is present across from the replication origin. DNA polymerase movement is stopped by the TUS protein (terminus utilization substance), which binds to the terminator region. It causes cessation.

DNA Function

The genetic material that contains all of our genetic information is called DNA. DNA is divided into tiny parts called genes, which typically include between 250 and 2 million base pairs. One amino acid is represented by the sequence of three nitrogenous bases in a gene that codes for a polypeptide molecule.

To create distinct proteins, polypeptide chains are further folded into secondary, tertiary, and quaternary structures. Since the DNA of every organism is made up of numerous genes, different kinds of proteins can arise. In most species, proteins serve as the primary structural and functional molecules. In addition to holding genetic information, DNA is used in:

  • Replication is the process of evenly distributing DNA during cell division and transferring genetic information from one cell to its daughters as well as from one generation to the next.
  • alterations The alterations that take place in DNA sequences
  • Interpretation
  • The Metabolism of Cells
  • RNA Bioprinting
  • Genetic Counseling

Why is a polynucleotide molecule called DNA?

Because the DNA molecule is made up of nucleotides, such as deoxyadenylate (A), deoxyguanylate (G), deoxycytidylate (C), and deoxythymidylate (T), which are joined to form long chains known as polynucleotides, the DNA is known as a polynucleotide. The DNA is made up of two chains of polynucleotides, according to the structure of DNA.

Frequently Asked Questions – DNA: Structure, Function and Discovery

What is the DNA’s structure?

Nucleotides make up the double helix structure of DNA. Hydrogen bonds bind the two helices together. Additionally, the DNA has a sugar-phosphate backbone.

Which three forms of DNA are there?

Among the three distinct forms of DNA are:


What distinguishes Z-DNA from other types of DNA?

Z-DNA is a double helix with one hand. The helix winds zigzag-style to the left. A and B-DNA, on the other hand, are right-handed DNA.

What roles does DNA play?

Among the roles that DNA plays are:

  • Gene expression
  • Transcription
  • Replication
  • Mutation

What kind of DNA is present in people?

Humans include B-DNA. It has a double helix structure with a right hand.

About The Author

Knowledge Glow

I am Komal Gupta, the founder of Knowledge Glow, and my team and I aim to fuel dreams and help the readers achieve success. While you prepare for your competitive exams, we will be right here to assist you in improving your general knowledge and gaining maximum numbers from objective questions. We started this website in 2021 to help students prepare for upcoming competitive exams. Whether you are preparing for civil services or any other exam, our resources will be valuable in the process.

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