Read the given passage and answer the following questions:
In the preceding sections you have learnt that it is the sequence of bases in DNA that determines the genetic information of a given organism. In other words, genetic make-up of an organism or an individual lies in the DNA sequences. If two individuals differ, then their DNA sequences should also be different, at least at some places. These assumptions led to the quest of finding out the complete DNA sequence of human genome. With the establishment of genetic engineering techniques where it was possible to isolate and clone any piece of DNA and availability of simple and fast techniques for determining DNA sequences, a very ambitious project of sequencing human genome was launched in the year 1990. Some of the important goals of HGP were as follows: (i) Identify all the approximately 20,000-25,000 genes in human DNA; (ii) Determine the sequences of the 3 billion chemical base pairs that make up human DNA; (iiii) Store this information in databases; (iv) Improve tools for data analysis; (v) Transfer related technologies to other sectors, such as industries; (vi) Address the ethical, legal, and social issues (ELSI) that may arise from the project. The Human Genome Project was a 13-year project coordinated by the U.S. Department of Energy and the National Institute of Health. During the early years of the HGP, the Wellcome Trust (U.K.) became a major partner; additional contributions came from Japan, France, Germany, China and others. The project was completed in 2003.
Which human chromosome was the last of the 24 human chromosomes to be sequenced in the HGP?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Chromosome 1
In the HGP the human DNA was broken into small fragments, each fragment was sequenced, and computer programs then lined up the overlapping sequences. The finished sequences were annotated and assigned to each chromosome. This work went on after 2003, the year the project was completed. Of the 24 human chromosomes (22 autosomes, X and Y), the last one to be finished was chromosome 1, in May 2006.
NCERT Extract:
Human Genome Project – “… These sequences were then arranged based on some overlapping regions present in them. This required generation of overlapping fragments for sequencing. Alignment of these sequences was humanly not possible. Therefore, specialised computer based programs were developed (Figure 5.15). These sequences were subsequently annotated and were assigned to each chromosome. The sequence of chromosome 1 was completed only in May 2006 (this was the last of the 24 human chromosomes – 22 autosomes and X and Y – to be sequenced).”