Why is DNA Negatively Charged?


We often hear the words genes, DNA, RNA, genetics and so much more. Are all of these interrelated? How does an individual get their habits or genes from? What is the most basic level? 

Well, all of this comes down to DNA. All your habits and genes are interrelated with DNA. What is it? Why does DNA have a negative charge? What is its structure? The organic materials called nucleic acids are present in the organisms in the form of DNA or RNA. The structure of DNA defines how the genes are made up in our bodies. As a matter of fact, it defines the genetic structure for the majority of organisms on the planet. 

Let us help you understand the details of DNA. 

What is DNA?

DNA stands for Deoxyribonucleic Acid, having a molecular structure that is unique. This can be found in both eukaryotic and prokaryotic cells of the organisms. 

DNA is defined as a group of molecules which carry out the transmission of hereditary materials from parents to their offsprings. This also holds true for viruses. Some viruses just contain RNA in the form of their genetic material, while for others DNA plays this role. 

DNA is not just responsible for carrying genetic information. Along with this, it is also responsible for protein production in living beings. The DNA which is contained inside the nucleus of all organisms is defined as nuclear DNA. Most of the organisms’ genomes are handled by this, while the plastid DNA and mitochondrial DNA are responsible for handling the rest. 

Mitochondrial DNA is the one that is stored inside the cell’s mitochondria. This is inherited by the child from their mother. There are approximately 16,000 mitochondrial DNA pairs present in the human body. 

Discovery of DNA

The Swiss biologist named Johannes Friedrich Miescher identified DNA in 1869 when he was conducting his research on white blood cells. Following this, the experimental data provided by Francis Crick and James Watson lead to the discovery of double helix structure. 

Types of DNA

DNA is mainly found in three different types, namely:

  • A-DNA: This one is similar to the B-DNA form, and is a right-handed double helix structure. During extreme conditions of desiccation, dehydrated DNA takes the A form. Following this, the protein binding leads to the removal of solvent from the DNA. 

  • B-DNA: This is a right-handed helix structure and is the most common DNA form. Under the normal physiological conditions, this one exists the most. 

  • Z-DNA: In this, the structure is a left-handed helix. It plays some role or the other in the regulation of genes. 

What is the Structure of DNA?

The DNA structure can be aptly explained with an example of a twisted ladder. This structure is called a double-helix. The DNA is a nucleic acid, and these are all further made up of nucleotides. 

Each nucleotide further contains components namely sugar, nitrogen bases, and phosphate groups. Nucleotides are linked together by sugar and phosphate groups leading to the formation of each DNA strand. 

There are mainly four types of nitrogen bases namely, Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Following this, the coiling up of DNA takes place leading to the formation of chromosomes. 

Functions of DNA

All the hereditary information is carried out by genetic material called DNA. The small segments of DNA are called genes, which consist mainly of 250-2 million base pairs. DNA leads to the formation of proteins, which are the structural molecules for many organisms. Along with genetic information storing, DNA carries out the following functions:

  • Replication Process: Under this, the transfer of genetic information from parent cell to daughter cells takes place, leading to equal distribution of DNA during the cell division process. 

  • Mutations: Under this process, changes take place in DNA sequences. 

  • Transcription

  • Cellular metabolism

  • Gene therapy

  • DNA fingerprinting

Why is DNA Negatively Charged?

Well, this is a question for many. Why does DNA have a negative charge? It happens because the nucleotides contain phosphate groups. 

The bonds created between oxygen and phosphorus atoms are negative, which makes the phosphate backbone negative. In the complete DNA structure, the phosphate group contains only one oxygen atom that is negative. However, this makes the complete structure negative. 

FAQs (Frequently Asked Questions)

1. Why is DNA Negatively Charged and Why is it Important For Gel Electrophoresis?

Ans. Due to the negative charge of the DNA, when an electric current is passed through the gel, the DNA starts moving towards the electrodes that are positively charged. The shorter DNA strands move faster as compared to the longer ones, making it easier to fragment the DNA of different lengths. This makes the negative charge of the DNA important for gel electrophoresis. 

2. What is the Difference Between Z-DNA and the Other DNA Forms?

Ans. Z-DNA has a left-handed double-helix structure, unlike the others which have a right-handed structure.

3. Which Form of DNA is Found in Humans?

Ans. Humans have the B-DNA form, which has a double-helical structure in right-handed form.