Difference Between Gene and DNA

The key difference between gene and DNA is that a gene refers to a particular segment of DNA that contains a specific genetic code to produce a protein while DNA is a type of nucleic acid that works as the genetic material of an organism.

DNA is a biomolecule. In fact, it is one of the two types of nucleic acids. DNA molecules collectively make the genome of an organism that is located inside the nucleus of eukaryotic organisms. Deoxyribonucleotides make up the DNA. It contains coding sequences as well as non-coding sequences. Moreover, coding sequences bear the genetic information to produce proteins. These specific fragments of DNA are the functional units of our genome and they are the genes.

CONTENTS

1. Overview and Key Difference
2. What is a Gene 
3. What is DNA
4. Similarities Between Gene and DNA
5. Side by Side Comparison – Gene vs DNA in Tabular Form
6. Summary

What is a Gene?

Gene is a functional unit of a genome. It refers to a specific fragment of DNA molecule that encodes for a protein. In other words, a gene is a particular fragment of DNA that holds genetic information to produce a protein. Genes pass from parents to offspring and they carry all the traits they code. Gene locus is the specific location of a gene on a chromosome. Generally, each gene has two alternative forms or variants called alleles. Alleles of a gene are located in the same positions as the homologous chromosomes that came from each parent: mother and father. Alleles can be dominant or recessive. When the dominant alleles are present either in heterozygous or homologous states, the dominant trait appears in the phenotype. On the other hand, the recessive trait appears when the homozygous recessive state of a gene is present.

There are thousands of genes in one chromosome. The human genome consists of over 20,000 genes, and certain genes of humans are also found in other animals and even in certain plants. It is because life on earth has evolved from simple to more complex organisms.

What is DNA?

DNA is a nucleic acid that contains heredity information of all living organisms except some viruses. Moreover, DNA molecules are macromolecules composing deoxyribonucleotides. They fold with histone proteins and package into chromosomes. The human genome has a total of 46 chromosomes and it contains about 3 billion bases pairs. Genes are fragments of DNA.

DNA exists as a double-stranded helix. Two complementary DNA strands join with each other via hydrogen bonds. These nucleotide chains consist of four types of nucleobases: adenine, thymine, guanine, and cytosine. The orders of these bases are different among individuals as well as among species. The backbone of the nucleotide chains is made of sugars and phosphate groups joined by phosphodiester bonds. Eukaryotes store most of their DNA inside their nucleus while prokaryotes store their DNA in the cytoplasm. In addition to nuclear DNA, eukaryotic cells have non-genomic DNA inside the mitochondria and chloroplasts.

What are the Similarities Between Gene and DNA?

• A gene is a small fragment of DNA. Hence, genes are made from DNA.
• Also, both DNA and gene contain genetic information.
• Besides, both are made up of deoxyribonucleotides.

What is the Difference Between Gene and DNA?

Gene is a specific fragment of DNA while DNA is a double helix macromolecule composed deoxyribonucleotides. So, we can consider this as the key difference between gene and DNA. Also, one more significant difference between gene and DNA is that the gene encodes for a protein while the DNA represents the genetic material of an organism. Moreover, the human genome has about 20,000 genes while it contains DNA composed of 3 billion base pairs. Hence, this is also a difference between gene and DNA.

Below infographic summarizes the difference between gene and DNA.

Summary – Gene vs DNA

In summarizing the difference between gene and DNA, the gene is a fragment of DNA that encodes for a protein. Wherein, the DNA is a nucleic acid and a macromolecule that works as the genetic material of living organisms. Moreover, DNA contains coding and noncoding sequences. However, most DNA is non coding DNA. Since genes are made from DNA, both genes and DNA are found in the chromosomes.

Reference:

1. “What Is a Gene? – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, Available here.
2. Britannica, The Editors of Encyclopaedia. “DNA.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 10 Dec. 2018, Available here.

Image Courtesy:

1. “Gene structure” by Genomics Education Programme (CC BY 2.0) via Flickr
2. “Eukaryote DNA-en” By Eukaryote_DNA.svg: *Difference_DNA_RNA-EN.svg: *Difference_DNA_RNA-DE.svg: Sponk (talk)translation: Sponk (talk)Chromosome.svg: *derivative work: Tryphon (talk)Chromosome-upright.png: Original version: Magnus Manske, this version with upright chromosome: User:Dietzel65Animal_cell_structure_en.svg: LadyofHats (Mariana Ruiz)derivative work: Radio89derivative work: Radio89 – This file was derived from: Eukaryote DNA.svg (CC BY-SA 3.0) via Commons Wikimedia