Human Genome Project: An Introduction
The Human Genome Project is based on the fact that isolating and analysing the genetic material contained in DNA can provide scientists with powerful new approaches to understanding disease development and developing new strategies for disease prevention and treatment. Except for physical injuries, nearly all human medical conditions are linked to changes (i.e., mutations) in the structure and function of DNA. The HGP accelerated the growth of bioinformatics, a vast field of study.
The project's primary goal is to create research tools that enable scientists to identify genes involved in rare and common diseases. In this article, we will study the various features of this megaproject as well as its applications in various fields, and the steps taken up by scientists to sequence the whole genome.
What is the Human Genome Project?
The Human Genome Project is an international research project with the primary goal of deciphering the chemical sequence of the entire human genetic material (i.e., the entire genome). It identifies all 50,000 to 100,000 genes contained within the genome and provides research tools to analyse all of this genetic information.
After the US government picked up the idea in 1984 and began planning, the project was formally launched in 1990 and completed in 2003.
The National Institutes of Health (NIH) of the United States, as well as numerous other organisations from around the world, provided funding.
The Human Genome Project (HGP) aims to determine the sequence of chemical base pairs that comprise human DNA, map the entire human genome, and identify its complex structures and functions.
Differences in the genetic make-up are caused by differences in DNA nucleotide sequences. The goal of scientists has always been to map the human genome. Advances in genetic engineering techniques have made it possible to isolate and clone DNA fragments and determine their nucleotide sequences.
The HGP has transformed biology with its multidisciplinary approach to deciphering a reference human genome sequence.
This audacious endeavour resulted in the creation of novel technologies and analytical tools.
Finally, the HGP has inspired several other exciting projects that have the potential to open up new avenues in biology, medicine, and psychology.
Aim and Objective of the Human Genome Project
To sequence the whole genome at 3 billion bps.
To create a physical map of the human genome.
To store this information in the database.
To improve the tools for data analysis.
To transfer this information to the other related industries.
To solve any ethical, legal, or social issues regarding this project.
To make the information available to all the researchers.
Steps of the Human Genome Project
The whole DNA of the cell is isolated and randomly broken into fragments.
They are inserted into special vectors like BAC (Bacterial Artificial Chromosomes) and YAC (Yeast Artificial Chromosomes).
These fragments are then cloned into suitable hosts like bacteria and yeast.
A Polymerase Chain Reaction (PCR) is used to make copies of DNA fragments.
The fragments are sequenced using Sanger sequencing.
The sequences are then arranged based on the overlapping regions.
The sequences were then annotated and assigned to different chromosomes.
The genetic and physical maps are also made with the help of polymorphism of microsatellites and restriction endonuclease.
Steps used in Human Genome Project Image
Salient Features of the Human Genome Project
The human genome is made up of 3164.7 million nucleotides.
The average gene is 3000 base pairs long. On the X-chromosome, the largest gene is Duchenne Muscular Dystrophy. It has 2.4 million base pairs (2400 kilo). The genes for B-globin and insulin are less than 10 kilobases long.
The human genome contains approximately 30,000 genes. It was previously estimated that it contained 80,000 to 100,000 genes. The number of genes in humans is roughly equal to that of mice.
More than half of the discovered genes' functions are unknown.
Proteins are coded for in less than 2% of the genome.
Repetitive sequences are nucleotide sequences that are repeated hundreds or thousands of times. They do not directly code but provide information about chromosome structure, dynamics, and evolution.
Approximately 1 million copies of short 5-8 base pair repeated sequences are clustered around centromeres and near the ends of chromosomes. They represent junk DNA.
Chromosome I has the most genes (2968) and Y has the fewest (231).
In humans, there are approximately 1.4 million locations where single-base DNA differences (SNPs- Single nucleotide polymorphism) occur.
Structure of DNA
The Technique Used in HGP:
The Human Genome Project used Sanger sequencing to determine the sequences of relatively small fragments of human DNA (900 bp or less).
These fragments were then used to piece together larger DNA fragments and, eventually, entire chromosomes.
The advancement of next-generation sequencing (NGS) technologies has accelerated genomics research.
Applications of Human Genome Project
Gene discovery also opens up the possibility of developing gene-based treatments for both hereditary and acquired diseases.
It's detailed genetic, physical, and sequence maps will also be critical in understanding the biological basis of complex disorders caused by the interaction of multiple genetic and environmental influences, such as diabetes, heart disease, cancer, and psychiatric illnesses such as alcoholism.
It helps in the identification of mutations linked to different forms of cancer.
It also helps in advancing research in Forensic Sciences.
Agriculture, environment, and biotechnology are some other fields that have benefitted from the use of human genome projects.
Diversity of Genomic Applications to Various Fields
Conclusion
The Human Genome Project (HGP) is an international scientific research project that aimed to identify, map, and sequence all of the genes in the human genome from both a physical and functional standpoint. Each individual's "genome" is unique; mapping the "human genome" requires sequencing a small number of individuals and then assembling these to obtain a complete sequence for each chromosome. As a result, the completed human genome is a combination that does not represent any single individual.
FAQs on Human Genome Project
1. What is a draft genome sequence vs a finished genome sequence?
Coverage, the number of gaps, and the error rate determine which ones are draft genome sequences and which ones are finished genome sequences. The draft sequence managed to cover 90% of the genome and had an error rate, which was 1 in 1000 base pairs. However, there were over 150,000 gaps with the presence of only 28% of the genome, which had gone up to the finishing. In 2003, in the month of April, there were around 400 gaps, with 99% of the genome reaching the finishing stage and the error rate of 1 in 10,000 base pairs.
2. What is a genome?
A set of deoxyribonucleic acids, also commonly known as DNA, is called a genome. This chemical compound has valuable information pertaining to genetics, studying which one can analyze and develop the functions of every organism. DNA molecules are composed of two strands that are twisted and are found in pairs. Every individual strand is composed of four chemical compartments, which are adenine (A), thymine (T), guanine (G), and cytosine (C). A is always paired with T, and C is always paired with G i. e, they are paired with opposite strands.
3. What are the medical benefits of the Human Genome Project?
Human genome project has been very beneficial for the field of molecular medicine. It contributed to better diagnosis of diseases and early detection of certain diseases which can be very harmful to the human body. It also helped in gene therapy. Due to the Human Genome Project,in the future, there will be molecular medicine that doesn't treat the symptoms but works on the cause of the problem at hand. Thus, the Human Genome Project has proved out to be very beneficial for the medicinal field.
4. What is Whole Genome sequencing?
Whole-genome sequencing is also known as complete genome sequencing, full genome sequencing, or entire genome sequencing etc. It is the process of examining the entirety of the DNA sequencing of someone's genome. This includes sequencing of all the chromosomal DNA of a human body, as well as the DNA contained in the mitochondria. In the case of plants, It examines and sequences the chloroplast. It is a wide form of sequencing and has many other concepts related to it.
5. How is the Human Genome profile calculated?
The result of the human genome profile is based on intron and exon distribution. Here, Introns are the sequence that separates the gene's protein coding sequence. Exons are the protein coding sequences of the genes. This calculation uses very minute parameters and has great accuracy. According to the human genome project, the percentage of introns ranged between 24% to 37%. Also, In the chromosomes, 80% of the exons are smaller than 200 bp in length. The total value of intergenic and introns DNA on each chromosome is correlated to the size of that chromosome. This way, scientists determined the sequence of chemical bases that forms the human DNA.
6. What was an economic drawback of the Human Genome program?
One of the main drawbacks of this project was related to insurance claims. People were afraid that employers and health insurance companies would refuse to provide health insurance to people because of a health concern indicated by someone's genes.For this, the government passed the 'Health Insurance Portability and Accountability Act' to protect the people from unauthorized release of someone's health information. For the Human genome program, the government decided the starting budget of USD1.57 million in 1990, but later it was increased to around USD18 million in 2014.
7. What is the difference between physical mapping and genetic mapping?
There are two types of maps used in genome mapping: genetic and physical. The differences include:
Genetic maps are based on genetic linkage information, whereas physical maps are based on actual physical distances as measured by the number of base pairs.
The two most important factors in genetic mapping are genetic markers and the size of the mapping population. However, physical mapping necessitates the fragmentation of the genome, either through restriction digestion or physical shattering.
Genetic maps frequently provide insights into the nature of different chromosomal regions, whereas physical maps provide a more accurate representation of the genome.
8. What are the future challenges of the Human Genome Project?
Various challenges faced by scientists are:
It is a massive task that will necessitate the expertise and creativity of many people from various disciplines in both the public and private sectors worldwide.
New high-throughput technologies and a large sum of money will be required.
Moving, analysing, interpreting, and storing large amounts of genetic data requires significant resources and costs, many of which are currently beyond the capabilities of the majority of routine diagnostic laboratories.
Scientists must keep in mind the ELSI (Ethical, Legal and Social Issues).
9. Which topics are frequently asked about from the Human Genome Project in the examination?
Human Genome Project is one of the most interesting topics in molecular biology, and also you’ll be able to see one or two questions from this topic in the examination. They generally ask about the process and key steps used in this project, the human genome project diagram, and the use of different enzymes. Role of PCR, sequencing, restriction endonuclease, vectors such as bacterial artificial chromosome and yeast artificial chromosome and their role. A student is advised to make proper human genome project notes for easy revision and recall.
