About human genome project class 12th biology


Technology is reaching skies and biology also being so helpful in understanding the human body. What if we clutch them together and make something good out of it ? Well, this is known as biotechnology.

By the help of biotechnology we can produce vitamins, antibiotics from living organisms. Even the branch of biotechnology has advanced and there was this project started called the Human Genome Project (HGP).

We will read about this further but first lets start by understanding what does the word genome mean as the whole project is based on it.

What is genome ?

When all the genes are packed together in a bundle that is known as a genome. Genes are written in a chemical code called DNA and the DNA is stored in long thread like structures called the chromosomes.

 Chromosomes showing DNA
Chromosomes showing DNA
In prokaryotic organisms there is only one chromosome so that means only one set of genes is present making them haploid in nature. Whereas in eukaryotic organisms there are two sets of genes that means they are haploid.

Study of genes and genomes which is taken place by the process of DNA sequencing is called as genomics and thanks to genomics this human genome project was conducted. Genomics helps researchers to know more about molecular biology of genes, its structure and functions, gene expression control gene evolution and mutation.

A genome consist of information which is important for the growth and maintenance of the organism. It includes a nuclear and mitochondrial DNA. If you don't know the different between mitochondrial DNA and nuclear DNA just click here, it will take you to my another article :)

Features of genome:

These are the following features genome:
  1. A genome contains 3164.7 million nucleotide bases. Nucleotide bases are Adenine, Guanine, Cytosine and Thymine
  2. An average gene consist of 3000 bases, the size of each is different. The largest known human gene is dystrophin which has 2.4 million bases
  3. The HGP had estimated that the total number of genes would be around 80,000 to 1,40,000 genes but when they investigated the total number of genes were estimated at 30,000
  4. In all people the nucleotide bases are same i.e. Adenine, Guanine, Cytosine and Thymine. 
  5. There are still unknown functions of the 50% of discovered genes. 
  6. Repeated sequence of a gene make a large portion of the human genome. 
  7. As you know there are two chromosomes. Chromosome X has the most genes i.e. 2968 where as chromosome Y has the fewest genes i.e. 231
  8. With the help of genes scientist can know more about human history, any disease can be found through chromosomal locations, etc. 

Why is genome important ?

As we know, genome is genes packed in a bundle. These genes are important for the growth and development of a human being as they carry all the genetic information form our parents. It is like a blueprint of a person.

A gene carries genetic information like it inherits traits from our parents such as physical traits, diseases that can be heredity, etc.. It can also help in protein determination or how will the offspring look, how well can its body metabolizes food, etc.

About Human Genome Project:

The HGP studied the base sequences of the DNA molecules present in the complete set of chromosomes is called Human Genome Project (HGP). It was a 13 year old project. This project was coordinated by the US department of Energy and National Institute of Health.

The Human Genome Project (HGP) was an international scientific project which was started in the year 1990 and was called a mega project. It has developed a new area in biology called the Bioinformatics.

The project was completed in the 2003 which was 5 years prior than the given time. There were 12 countries which participated in the genome research and countries like Japan, France, Germany, China and others gave additional contributions to the project.

The scientist had estimated that there is presence of around 80,000 to 100,000 genes, but when they completed this research the total number of genes were 20,000 to 25,000. As there are 3 billion base pairs in the human genome, the HGP had to sequence all of them in order to complete this project.

This project helped in understanding our biology and behaviour by sequencing that 3 billion base pairs (AH! Must have been so much work). Why was it so necessary to sequence and know more about the human genome ?

Well, when we have the knowledge about something, we can gain more out of it. To make it simple, the scientist obtained knowledge from the human genome that will broader their research field and we can know about more diseases linked to it, immediate diagnosis can take place and can treat it as soon as possible. Maybe someday we will also be able to prevent some disorders that can or maybe is still affected human beings.

HGP sequenced and mapped genomes from E.coli, Arabidopsis thaliana, Saccharomyces cerevisiae, Drosophila melanogaster, Caenorhabditis elegans, Mus musculus, etc.

As humans share the same genes as that of flies, round worms and mice, studying about the genome can lead to understanding of how were humans actually evolved as there are only theories and not much of solid proofs.

Goals of the HGP:

Here are some of the goals of the human genome project:

  • Identification of all the 20,000-25,000 genes present in the human DNA. 
  • Sequence all the 3 billion base pairs that makes up the human DNA. 
  • The information obtained should be stored in the databases. 
  • Advanced tools for the data analysis. 
  • Share the related technologies with other sectors such as industries
  • Address the ethical, legal and social issues that may come from the project. 
  • Generate a detailed map about the human genome. 

Types of maps of the human genome:

The maps that would be generated by the HGP would be helpful in knowing the location of the gene that are present in the human genome. There are two types of maps:
  1. Genetic linkage map - This map tells you the arrangement of the genes and the approximate distance between the genes
  2. Physical map - This map gives the physical location (but only in base pairs) and the distance between the gene or DNA fragment

Methodology of HGP:

The HGP had two major approaches, which are as follows:
  1. Expressed Sequence Tags (ESTs) - This approach mostly focuses on identifying the genes that are expressed as RNA
  2. Sequence Annotation - This is blind approach. This approach focuses on sequencing the whole set of genomes which consisted of all the coding and non-coding sequence and to assign different regions in the sequence functions
At first the DNA from the cell is isolated and then they are converted into fragments which are smaller in size. Later they clone these fragments into the suitable host using the specialised vectors. The fragments were sequenced using an automated DNA sequencer as it was not possible to do it manually. 

 DNA sequencer
DNA sequencer

The alignment of the sequences is taken place via specialised computer programmes that were specially made for this purpose. 

 Computer programme for alignment of the sequence
Computer programme for alignment of the sequence

After the alignment, the sequences are looked at for the final time and then are set into the chromosomes. This indeed is a time consuming process. The sequence of chromosome 1 was completed in May in the year 2006.

The host cells that were used were bacteria and yeast and their vectors are called as BAC i.e. Bacterial Artificial Chromosomes and YAC i.e. Yeast Artificial Chromosomes

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