The Complete Human Genome
- April 2, 2022
- Posted by: OptimizeIAS Team
- Category: DPN Topics
The Complete Human Genome
Subject: Science & Tech
Context- Two decades after most of the human genome was mapped, scientists have now filled in the gaps that remained.
- Nearly two decades ago, when scientists published the map of the human genome for the first time, it was hailed as a breakthrough.
- That was incomplete, however: about 8% of the human DNA was left unsequenced.
- Now, in a series of papers published in Science, a large team has accounted for that 8%, completing the picture of the human genome for the first time.
What was missing:
- The genetic sequence made available in 2003 from the Human Genome Project, an international collaboration between 1990 and 2003, contained information from a region of the human genome known as the euchromatin. Here, the chromosome is rich in genes, and the DNA encodes for protein.
- The 8% that was left out was in the area called heterochromatin. This is a smaller portion of the genome, and does not produce protein.
- Now, the fully sequenced genome is the result of the efforts of a global collaboration called the Telomere-2-Telomere (T2T) project.
- What’s in the 8%
What does genome-mapping tell us?
- According to the Human Genome Project, there are estimated to be over 20,500 human genes.
- Genome refers to an organism’s complete set of DNA, which includes all its genes and mapping these genes simply means finding out the location of these genes in a chromosome.
- In humans, each cell consists of 23 pairs of chromosomes for a total of 46 chromosomes, which means that for 23 pairs of chromosomes in each cell, there are roughly 20,500 genes located on them.
- Some of the genes are lined up in a row on each chromosome, while others are lined up quite close to one another and this arrangement might affect the way they are inherited.
- For example, if the genes are placed sufficiently close together, there is a probability that they get inherited as a pair.
- Genome mapping, therefore, essentially means figuring out the location of a specific gene on a particular region of the chromosome and also determining the location of and relative distances between other genes on that chromosome.
Significance of Genome Mapping:
- A complete human genome makes it easier to study genetic variation between individuals or between populations.
- Genome mapping enables scientists to gather evidence if a disease transmitted from the parent to the child is linked to one or more genes.
- Mapping also helps in determining the particular chromosome which contains that gene and the location of that gene in the chromosome.
- According to the National Human Genome Research Institute (NHGRI), genome maps have been used to find out genes that are responsible for relatively rare, single-gene inherited disorders such as cystic fibrosis and Duchenne muscular dystrophy.
- Genetic maps may also point out scientists to the genes that play a role in more common disorders and diseases such as asthma, cancer and heart disease among others.
Human Genome Project:
- In 1990, with support from the US and widespread international collaboration and cooperation, the $3 billion dollar Human Genome Project was launched.
- The project aimed to determine the sequence of the human genome within 15 years.
- Human genome project (HGP) got successfully completed in the year 2003 by sequencing the almost entire human genome (except 8%) of 3.3 billion base pairs.