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What is a Genome?

BioCodeKb - Bioinformatics Knowledgebase

A genome is an organism’s complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism and passing life on to the next generation. The instructions in our genome are made up of DNA that guides our growth, development and health. This information is stored in the coding language of DNA nucleotides in the genome.

In most living things, the genome is made of a chemical called DNA. The genome contains genes, which are packed in chromosomes and affect specific characteristics of the organism.

The term genome was created in 1920 by Hans Winkler, professor of botany at the University of Hamburg, Germany. The Oxford Dictionary suggests the name is a blend of the words gene and chromosome.  Since every cell contains the exact same DNA and genome, it is therefore the levels of gene expression that determine whether a cell will be a neuron, skin, or even an immune cell. Each one of earth's species has its own distinctive genome: the dog genome, the wheat genome, the genomes of the cow, cold virus, bok choy, Escherichia coli (a bacterium that lives in the human gut and in animal intestines), and so on.

In humans, a copy of the entire genome, more than 3.2 billion DNA base pairs, is contained in all cells that have a nucleus.

Organization of Genetic Material

The vast majority of an organism’s genome is organized into the cell’s chromosomes, which are discrete DNA structures within cells that control cellular activity.

Eukaryotic chromosomes are typically linear, and eukaryotic cells contain multiple distinct chromosomes while in prokaryotic cells, the genetic material is carried on a single circular piece of DNA which is attached to the cell membrane and in direct contact with the cytoplasm.

The length of a chromosome greatly exceeds the length of the cell. For example, the combined length of all of the 3.2 billion base pairs of DNA of the human genome would measure approximately 2 meters if completely stretched out. So, the genome needs to supercoil in the cell to fit in the space of cell. DNA supercoiling means the process by which DNA is twisted to fit inside the cell. Supercoiling may result in DNA that is either underwound (less than one turn of the helix per 10 base pairs) or overwound (more than one turn per 10 base pairs) from its normal relaxed state. Proteins known to be involved in supercoiling include topoisomerases; these enzymes help maintain the structure of supercoiled chromosomes, preventing overwinding of DNA during certain cellular processes like DNA replication.

Benefits of knowing about the Genome

  • Analysis to the drug discovery process

  • Help to know its products and their effects

  • To compare genome of different organisms to find similarity and differences

  • Stratifying  tumours for treatment

  • Drug prescription and development

  • Diagnosing and characterizing genetic disease

  • From disease diagnosis to personalized genetic health

  • Integrating genomic and clinical information

  • Storing and sharing population data

  • Identification of disease genes


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