2. HUMAN GENOME PROJECT
HISTORY AND SILENT FEATURE :
In 1990, US Department of energy and national institute of health embarked and
coordinated on the project of sequencing human genome called HGP AND
HUMAN GENOME PROJECT.
Welcome trust (U.K) joined the project as major partner later on japan , France
,Germany ,china and some other countries also joint it.
JOHN CRAIG VENTER one of the first scientist to sequence human genome.
The human genome project was launched on oct 1, 1990. the project was
complete in 2003 . Thus it was a 13 year project.
3. HGP has been called a megaproject due
to:
Huge cost estimated to be 9 billion US dollars.
Very large number of bp (3 x 109 bp) to be identified and sequenced.
A large number of scientists, technicians and supporting staff is needed.
Storage of data generated which requires some 3300 books, each two pages
and earn page having 1000 typed letters.
The science of bioinformatics also developed during this period and helped HGP.
4. GOALS OF HGP:
Identification of the approximately 20,000 – 25,000 genes in human DNA.
To determine the sequence of the 3 billion chemical base pairs that make up human DNA.
To store this information in database.
To improve tools for data analysis.
Transfer related technologies to other sectors, such as pharmaceutical industries.
ELSI , To solve any ethical legal and social issues (ELSI) that may arise from that the project.
Bioinformatics , i.e close association of HGP area in biology.
Sequencing of model organisms, non human organisms DNA can lead to an understanding to
their natural capabilities.
5. Other organism whose genome was also
sequenced:
ORGANISM BASE PAIRS NO.OF GENES
1. E.COLI 4.7 M 4,000
2.SACCHAROMYCES
CEREVISIAE 12 M 6,000
3.CAENORHABIDITIS
ELEGANS 97 M 18,000
4.DROSOPHILA
MELANOGSTER 180 M 13,000
5. ARABIODOPSIS 130 M 25,000
6.ORYZA SATIVA 430 M 32,000 – 50,000
6. METHODOGIES:
There are two approaches foe sequencing human genome:
1. Expressed sequence tags (ESTs)
2. Sequence annotation (or define)
The whole DNA h the cell is isolated and broken randomly into fragments.
They are inserted into specialized vectors like BAC ( bacterial artificial
chromosome) and YAC (yeast artificial chromosome).
The fragment are closed in suitable hosts like bacterial and yeast.
The PCR (polymerase chain reaction) can also be used for cloning or making
copies of DNA fragments .
7. In HGP, sequence annotation has been
carried out which involves following
steps:
The fragment are sequenced as annotated DNA sequence (as shown of methodology)
developed by double novel LAUREATE FRIEDRICK SANGER.
The sequence were then arranged on the basis of some overlapping regions . It
necessitated the generation of overlapping fragments for sequencing.
Computer based programming were used to align the sequences.
The sequence were than annotated and assigned to different chromosome . All the
human chromosome have been sequenced , 22 autosome X and Y.
With the help of polymorphism In microsatellite and restriction endonuclease
recognition sites , the genetic and physical maps of the genome have also prepared.
8. Salient features of HGP:
The human genome contains 3164.7 million nucleotide bases.
The average gene consist of 3000 bases, but size vary greatly with the largest
known human gene being dystrophin at 2.4 million bases.
The total number of genes is estimates of 80,000 to 1,40,000 genes. Almost all
(99.9 percent) nucleotide bases are exactly the same in all people.
The functions are unknown for over 50 percent of discovered genes.
Less than 2 percent of the genome codes for proteins.
Repeated sequences make up very large portion of the human genome.
9. Repetitive sequences that are respected stretches of DNA sequences that are
thought to have no direct coding functions, but they shed light on chromosome
structure , dynamics and evolution.
Chromosome 1 has most genes (2968) and Y Has the fewest (231).
Scientist have identified about 1.4 million locations where single base DNA
differences (SNPs single nucleotide polymorphism) pronounced as ‘snips’ ) occur
in humans this information promises to revolutionise the processes of finding
chromosomal for diseases light on chromosome structure associated sequence
and tracing human history.
10. Application and future challenges:
1. DISORDERS – More than 1200 genes are responsible for commom human
cardiovascular diseases, endocrine disesases (like diabetes) neurological
disorders (like Alzheimer’s) diseases cancers and many more.
2. CANCER – efforts are in progress to determine genes that will change cancerous
cells to normal.
3. HEALTHCASE- it will indicate prospects for a healthier living, designer drugs ,
genetically modified diets and finally our genetic identify.
4. INTERACTIONS- It will be possible to study how various genes and proteins work
together in an interconnected network.
5. Study of tissues- all the genes or transcripts in a particular tissue , organ or
Tumor can be analysed to known the cause of effect produced in it.
6. NON HUMAN ORGANISMS- used I meeting challenges in health care ,
agriculture energy production and environmental remediation.