DNA, or deoxyribonucleic acid, is a molecule that contains the genetic instructions necessary for the development and functioning of all known living organisms. It consists of two long chains, known as strands, that coil around each other to form a double helix. The DNA is negatively charged. In this article, we will learn the answer to “Why is DNA Negatively Charged,” and the structure and function of DNA in detail.
Table of Content
What is DNA?
DNA is a genetic material that is present in every single organism from unicellular to multicellular organisms. It carries genetic information about a particular species. The full form of DNA is Deoxyribonucleic acid. DNA was discovered by a Swiss Biologist Johannes Friedrich Miescher, in the year 1869. Structurally, DNA is a double helix formed by two complementary strands of nucleotides, each containing a sugar-phosphate backbone and nitrogenous bases (adenine, thymine, cytosine, and guanine).
The sequence of these bases encodes genetic information. DNA is located in the cell’s nucleus in eukaryotes and in the nucleoid region in prokaryotes. Replication of DNA occurs during cell division, ensuring the inheritance of genetic material.
Also Read: Why Thymine is present in DNA instead of Uracil?
Structure of DNA
DNA or deoxyribonucleic acid is double helical polynucleotide chains. It contains genetic code that is unique for every individual. Genetic code is composed of three DNA nucleotides (codon) that correspond with a specific protein that is responsible for making different Structures, Enzymes & organs of our body. Now let’s study more about the structure of DNA. DNA is composed of a sugar-phosphate backbone and nitrogenous base pairs. There are two types of nitrogenous base pairs:
- Purine
- Adenine [A]
- Guanine [G]
- Pyrimidine
- Thymine [T]
- Cytosine [C]
Purine can form hydrogen bonds with pyrimidine, since they are present in pairs that is why we call it a nitrogenous base pair.
Why is DNA Negatively Charged?
DNA is negatively charged because of the presence of negatively charged phosphate groups. In the phosphate group there is single negatively charged oxygen, which makes the entire DNA negatively charged. Negativity of DNA helps in joining two strands of DNA together to form a double helical structure. Now let’s make the concept more clear about Double helical structure of DNA.
It is made up of two antiparallel polarities (one end of strand is 3’ to 5’ and ends of other strand is 5’ to 3’) nucleotides backbone which consists of Sugar-phosphate and one nitrogenous base on each strand. The nitrogenous base of one strand makes hydrogen bonds with corresponding nitrogenous bases and forms a helical structure. The two strands are right coiled handed. The pitch of the helix is 3.4 nm, around 10 base pairs and 0.34 nm is the distance between two base pairs that are present in turn of the helix.
Also Read: Difference Between DNA Polymerase 1, 2 And 3
Discovery of DNA
The discovery of DNA’s role as the genetic material transferring from generation to generation was confirmed by Alfred Hershey and Martha Chase’s 1952 experiment using bacteriophages.
- Working with bacteriophages, viruses that infect bacteria, they aimed to determine whether DNA or protein carried the hereditary information.
- Using radioactive phosphorus and sulfur, they labeled viral DNA and protein separately and observed their transmission to bacterial cells.
- Bacteria infected with viruses containing radioactive DNA became radioactive, confirming that DNA was the material transferred from the virus.
- Conversely, bacteria infected with viruses containing radioactive protein did not exhibit radioactivity, establishing DNA as the genetic material.
- This pivotal experiment clarified that DNA, not protein, is the carrier of genetic information during the transfer from viruses to bacteria.
Types of DNA
There are three types of DNA namely :
- Type A DNA: It is a right-handed double helical DNA made up of deoxyribonucleic acid. The two strands of type A DNA are antiparallel with each other and non symmetrical.
- Type B DNA: It is also a right-handed double helical DNA made up of deoxyribonucleic acid. This is the most common type of DNA, two anti parallel strands are held together by hydrogen bonds. Type B DNA is present in humans.
- Type Z DNA: It is left-handed DNA and it is known to form di nucleotide repeated sequences. Its biological significance is still unexplored.
Also Read: DNA Replication – Definition, Classification, Process, Examples
Functions of DNA
Function of the DNA are:
- Genetic Code: DNA carries the genetic instructions necessary for the development, functioning, and reproduction of living organisms.
- Protein Synthesis: DNA serves as a template for RNA synthesis, leading to the production of proteins through the process of transcription and translation.
- Inheritance: DNA is passed from one generation to the next, ensuring the transmission of genetic traits and information.
- Genetic Variation: DNA allows for the generation of diversity through mechanisms such as mutation and recombination.
- Cell Replication: DNA is replicated during cell division, ensuring that each new cell receives a complete set of genetic information.
- Storage of Information: DNA stores and preserves genetic information in the sequence of its nucleotide base pairs.
Also Read: What is the importance of Variation?
Conclusion – Why Is DNA Negatively Charged?
In conclusion, DNA is negatively charged because of the presence of phosphate groups in nucleotides. The phosphate backbone of DNA is negatively charged, which is due to the presence of bonds created between the phosphorus and oxygen atoms. In DNA structure, a phosphate group comprises one negatively charged oxygen atom, which is responsible for the entire strand of DNA to be negatively charged.
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FAQs on Why Is DNA Negatively Charged?
Who Discovered DNA for the First Time?
In 1869, Swiss biochemist Friedrich Miescher discovered DNA and developed techniques for extracting it.
Why DNA is a Genetic Material?
DNA is a genetic material because it carries genetic information that is read in cells to make proteins and RNA.
How Many Base Pairs are there in One Full Turn of the Double Helix DNA?
There are 10 base pairs in one full turn of the double Helical DNA.
Where is DNA Located ?
DNA is present inside the nucleus in all eukaryotes.
Which Part of Helix is Called as Backbone of DNA?
The phosphate backbone is the part of the DNA double helix that provides structural support to the molecule .
What Part of DNA is Negatively Charged?
Backbone of DNA containing the phosphate group is negatively charged.
What is the Charge of DNA in Gel Electrophoresis?
DNA is negatively charged, so when an electric current is applied to a gel, DNA will migrate towards the positively charged electrode.
Why is DNA negativley Charged and Why is it Important for Gel Electrophoresis?
DNA is negatively charged because of the negatively charged phosphate groups in its backbone. This is crucial for gel electrophoresis because it allows DNA molecules to move towards the anode when an electric field is applied. This movement through the gel matrix separates DNA fragments based on their size, with smaller fragments traveling farther than larger ones.
Is DNA more Negatively Charged than RNA?
Yes, DNA is more negatively charged than RNA due to the presence of phosphate groups in its backbone.
Why is DNA Acidic in Nature?
DNA is acidic in nature because of the phosphate groups in its backbone, which can release hydrogen ions in a solution.
What is the Advantage of Negative Charge DNA?
The negative charge of DNA helps stabilize its structure, allowing it to bind more readily with positively charged molecules like histones and enzymes, facilitating various cellular processes such as replication and transcription.