The Human Genome Project - goals and challenges


Do you know what is genome and the human genome project? In the below article you will find the meaning of genome and details about the human genome project, namely its features, goals and applications.

Genome concept

Each cell of the plants and animals contain the specific number of chromosome. Most of the species of living beings are sporophytic and contain diploid (2n) number of chromosomes and having two sets of chromosomes. Thereproductive cells of these living beings are haploid (n) and therefore having only one set of chromosome. The haploid number of chromosome of an organism is called its genome. In cytogenetics, genome means a single set of the chromosome, refers ordinarily to nuclear chromosomes and is denoted by (n). Therefore diploid organisms, genome represents the total genetic information present in them. The study of the structural and functional organization of the complete genome is referred to as genomic analysis. This is commonly termed as genomics. Initially, genomics consists of the development of the genome map. A genomic map may be defined as a detailed schematic description of the structural and functional organization of the complete genome of an organism.

The ultimate aim of genomics is to obtain the DNA sequence of the completed genome, which provides the most detailed molecular description i.e., the complete nucleotide sequence of the genome.

Human Genome Project(HGP) aspects

hgp
(Note: Image courtesy www.wikipedia.org)

Human Genome Project is an international research program or undertaking by many countries administered jointly by the National Institute of Health and Department of Energy (NIHDE) U.S.A. to acquire complete knowledge of the organization, structure, and function of the human genome. It is called International Human Genome Sequencing Consortium which is aimed at finding out all genes of all the human chromosomes, determining their function and hopefully understanding how they together form a complete organization. HGP was started in the mid of 1980s. The National Institute of Health, Bethesda, Maryland has established the first office of the HGP in the year 1988. James Watson was the first director of this project. The Human Genome Project official began on October 1, 1990.

The human genome is big. It consists of approximately 3 X 109 bp of DNA. So far the longest region of the continuous completed sequence is no more than about 10 6 bp. Sequencing a big genome does not just happen. It has to be carefully planned. The human genome project has preceded in three stages, first the construction of detail maps of what I will call "landmarks". Next, the complete cloning of the genome in well-characterized clones which include all the landmarks and finally the sequencing and annotation. Of all these the mapping has taken the longest time, the sequencing will take surprisingly little time but the annotation of the sequence is still to happen and is likely to take much longer than anything else.

Goals of the Human Genome Project

The Human genome project is an international research programme which is designed:

  • To construct a detailed genetic linkage map of the human genome by identifying thousands of genetic markers and mapping them in the genome. Over 9300 markers had been mapped to a particular chromosome.

  • To construct detailed genetic physical maps of the human genome by cloning genomic DNA into YACS and cosmids.

  • To determine the complete nucleotide sequence of the human genome (DNA). About 93.5% of the human genome had been sequenced. The complete sequence is known for only chromosome 21 and 22.

  • To localize the estimated 50000 – 100000 genes within the human genome.

  • To develop technology for the management of human genome information, by developing user-friendly tools.

  • To provide scientists with easy access to up to date information generated by the project and by developing analytical tools to interpret this information.

  • To perform similar analysis on the genomes of several other organisms used extensively in research laboratories as model systems. E.g. E.coli, Drosophila melanogaster, Arabidopsis thaliana, etc.

  • To develop programmes focused on understanding and addressing the ethical, legal and social implications of the results obtained from the project.

  • To develop technological advances in genetic methodologies such as DNA cloning, DNA sequencing, etc.

Salient features of Human Genome

Some of the important observations of the human genome project are as follows:
  • The human genome contains 3164.7 million nucleotides.

  • More than 99.9% of the nucleotides bases are identical in everyone. Less than 0.1% of our DN accounts for inherited differences among humans.

  • Surprisingly, at least half of the human genome consists of repeated sequences that do not code for proteins hence called junk DNA.

  • The average gene consists of 3,000 nucleotides, but sizes vary greatly. The largest known human gene consisting of 2.4 million nucleotides, codes for the protein dystrophin.

  • The total number of genes in the human genome is about 30,000 which is far fewer than the 1,00,000 previously predicted to exist.

  • Less than 2% of the genome codes for proteins.

  • Highest 2968 genes are found in chromosome 1 and lowest 231 genes are found in the Y chromosome.

  • Scientists have identified about 1.4 million locations where single-base DNA differences occur in the human genome. This is called the single nucleotide polymorphism (SNPs) or Snips. Such observation promises to revolutionize the processes of finding the chromosomal location for diseases-associated sequences and tracing human history.

Application and future challenges

The application and future challenges are given below:
  • Information about the human genome and how it is affected by the environment seeks to identify and discover the functions of the specific genes that play a role in genetic diseases.

  • Genomic medicines are also aimed to design new drugs and to provide screening tests to enable physicians to provide more effective counselling and treatment for disorders with significant genetic components, such as obesity, hypertension, diabetes, and cancer.

  • Appliances made in connection with human genome project have also been used in biological researches on a large scale such as in flatworms, fruit flies, mice, etc. Besides, efforts are being made for marking the complete genome of many other organisms.

  • Genomic study of plants can lead to the development of better means of disease control and better yield.

  • Improvement can be done in techniques related to forensic science.


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