July 18, 2024
Medical Science

What is DNA?


Last Update onĀ September 15, 2022


Deoxyribonucleic acid (DNA) holds all genetic information in humans and nearly all other species. The DNA of humans can be found mostly in all of their cells. The majority of Deoxyribonucleic acid is found in the nucleus of the cell (where it is called nuclear DNA). However, there are also small numbers of Deoxyribonucleic acid in the mitochondria (which is referred to as mitochondrial DNA or mtDNA). The function of mitochondrial DNA (mtDNA) is to convert the energy from food into a form that can be consumed by cells.

Adenine (A), guanine (G), cytosine (C), and thymine (C) are the four chemical bases that make up the code that stores the information in DNA (T). More than 99% of the 3 billion bases of Deoxyribonucleic acid that make up human DNA are the same in every person. Similar to how the letters of the alphabet occur in a specific order to form words and sentences, the order, or sequence, of these bases, keeps the information available for producing and maintaining a living organism.

DNA shape

DNA nucleotides link up to form units known as base pairs, A with T and C with G. Sugar and phosphate molecules are also joined to each base. A nucleotide consists of a base, sugar, and phosphate molecules.

The double helix is a spiral that is made up of two long strands of nucleotides. The base pairs serve as the ladder’s rungs while the sugar and phosphate molecules serve as the vertical side rails of the ladder in the double helix shape.

The ability of Deoxyribonucleic acid to replicate, or generate duplicates of it, is a basic fundamental. The blueprint for replicating Deoxyribonucleic acid, the base sequence can be found in each of the double helix’s DNA strands. When cells divide, this is important because each new cell required the same copy of the Deoxyribonucleic acid that was found in the old cell.

1. Types of DNA:

There are three different types of DNA:

  1. A-DNA: The double helix is right-handed and resembles the B-DNA type. DNA that has been dehydrated accepts the A form that protects it from harmful conditions like desiccation. Deoxyribonucleic acid takes on an A form as a result of protein binding, which also removes the solvent from DNA.
  2. B-DNA: This right-handed helix is the DNA shape. Under normal physical settings, most DNA has a B-type shape.
  3. Z-DNA: Z-DNA is a left-handed DNA whose double helix winds zigzag-style to the left. Alexander Rich and Andres Wang made the find. It is thought to play a part in gene regulation since it is located before the start point of a gene.

2. Location of DNA in the body:

DNA is located inside the nucleus, a specific region of the cell, in eukaryotic species. Each DNA molecule needs to be neatly packaged because cells are very small and organisms have several DNA molecules per cell. Chromosomes are the name for this Deoxyribonucleic acid that has been packed.

DNA present in Cell

DNA unwinds during DNA replication so that it can be copied. DNA also unravels at other points in the cell cycle so that its instructions can be employed to create proteins and for other biological functions. However, Deoxyribonucleic acid is in its compact chromosomal form during cell division to allow transfer to new cells.

Nuclear DNA is the term used by researchers to describe Deoxyribonucleic acid located in the nucleus of a cell. The entire nuclear DNA collection of an organism is referred to as its genome.

Humans and other sophisticated organisms also have a small quantity of DNA in cell structures called mitochondria, in addition to the DNA found in the nucleus. The energy that a cell requires to function correctly is produced by mitochondria.

When an organism reproduces sexually, it receives half of its nuclear Deoxyribonucleic acid from the male parent and the other half from the female parent. However, the female parent provides the creature with all of its mitochondrial Deoxyribonucleic acids. This happens as a result of the fact that only egg cells maintain their mitochondria during fertilization, not sperm cells.

3. Composition of DNA:

DNA is made up of Nucleotides which are the chemical building units. These building blocks are composed of a phosphate group, a sugar group, and one of four different nitrogen bases. Nucleotides are joined together into chains, with the phosphate and sugar groups switching places, to produce strands of DNA.

There are four different types of nitrogen bases that can be found in nucleotides:

  1. Adenine (A)
  2. Thymine (T),
  3. Guanine (G)
  4. Cytosine (C)

The biological instructions that are encoded in a strand of DNA are defined by the arrangement, or sequence, of these bases. As an illustration, the sequence ATCGTT might represent blue eyes, but ATCGCT might represent brown eyes.

ATCGTT represents Blue eyes
ATCGCT represents brown eyes

On 23 pairs of chromosomes, the human genome, which is the whole set of DNA instructions, comprises around 3 billion bases and 20,000 genes.

4. Functions of DNA:

The instructions required for an organism to grow, survive, and reproduce are stored in its DNA. DNA sequences must be transformed into messages that can be used to create proteins, which are the complex molecules that carry out the majority of the work in our bodies, in order to perform these activities.

A gene is any DNA sequence that provides the instructions needed to generate a protein. In humans, the size of genes can range between 1,000 bases to 1 million bases. Only 1% of the DNA sequence is made up of genes. The production of a protein can be controlled by Deoxyribonucleic consequences outside of this 1 percent.

Because of its highly stable configuration, the DNA molecule can serve as a template for both the creation (transcription) of the associated RNA (ribonucleic acid) molecule and the replication of new Deoxyribonucleic acid molecules. A gene is a section of DNA that codes for the production of a certain protein by the cell.

DNA Transcription

Proteins are created in two steps using DNA instructions. Enzymes first read the data from a DNA molecule and then translate it into a transitional molecule known as messenger ribonucleic acid, or mRNA.

The data in the mRNA molecule is next converted into the “language” of amino acids, which are the component elements of proteins. This language instructs the cell’s machinery for creating proteins the exact sequence in which to link the amino acids to create a particular protein. There are 20 different types of amino acids, and they can be combined in a variety of ways to create a wide range of proteins, making this a challenging undertaking.

Related Topic: What is RNA?