GS Paper 3
Syllabus: Science and Technology
Source: TH
Context: For the first time, the first complete end-to-end human genome has been published, as scientists have finally filled the gaps in the human genome that were previously too confusing to piece together.
What is Genome?
A genome is a genetic material that provides instructions for the development, growth, and functioning of all living organisms, composed of DNA with a sequence of chemical bases that determines an organism’s characteristics.
- German botanist Hans Winkler coined the word “genome” in 1920, combining the word “gene” with the suffix “-ome,” meaning “complete set,” to describe the full DNA sequence contained within each cell.
What is Genome Sequencing?
It is the process of determining the complete DNA sequence of an organism’s genome. It involves identifying the order of nucleotides (A, T, C, G) that make up the DNA molecule in each of the chromosomes of an organism.
An analogy to understand Genome:
The genome can be compared to a reference book. In this analogy, a genome contains the DNA– instructions for life. It’s composed of a vast array of nucleotides (letters) that are packaged into chromosomes (chapters). Each chromosome contains genes (paragraphs) that are regions of DNA which code for the specific proteins that allow an organism to function.
What was the issue?
Human Genome Project completed the first human genome in 2003. However, scientists weren’t actually able to put together all the genetic information in the genome. There were gaps: unfilled, often repetitive regions that were too confusing to piece together. With the advancement of technology, these gaps have been filled now.
Findings of the Complete Human Genome:
| Finding | Description |
| Number | The human genome contains roughly three billion nucleotides |
| Protein Coding genes | Just under 20,000 protein-coding genes (making up less than 2% of human DNA) |
| Non-Coding DNA | The remaining 99% of non-coding DNA sequences that do not produce proteins |
| Repetitive element | Over 50% of the human genome is repetitive, with multiple copies of near-identical sequences |
What is Repetitive DNA?
It refers to sequences of DNA that are repeated multiple times within the genome of an organism. These repetitive sequences can be short, consisting of just a few nucleotides, or very long, containing hundreds or thousands of nucleotides.
Usage: Some repetitive DNA sequences have been found to have important functions, such as regulating gene expression, maintaining the structure of chromosomes, and protecting against the insertion of foreign DNA. However, many repetitive sequences do not have a known function and are sometimes referred to as “junk DNA”.
What is Satellite DNA?
The simplest form of repetitive DNA is called satellites, which are blocks of DNA repeated over and over in tandem. Satellite DNA is found in telomeres, which are the protective ends of chromosomes, and in centromeres, which help keep genetic information intact during cell division.
Usage: Researchers use satellite DNA as a genomic “fingerprint” to match crime scene samples and track ancestry.
For Genome India Project and Human Genome Project: Click here
Mains Link:
What is Genome Sequencing and what are its benefits? Also, enumerate the steps taken by India in this direction. (10M)
Prelims Links:
With reference to agriculture in India, how can the technique of ‘genome sequencing’, often seen in the news, be used in the immediate future? (UPSC 2017)
- Genome sequencing can be used to identify genetic markers for disease resistance and drought tolerance in various crop plants.
- This technique helps in reducing the time required to develop new varieties of crop plants.
- It can be used to decipher the host-pathogen relationships in crops.
Select the correct answer using the code given below:
(a) 1 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans: D
