genomics

1. GENOME
SEQUENCING
SUBHANANTHINI JEYAMURUGAN,
18PY17, M.SC., MICROBIOLOGY.
AYYA NADAR JANAKI AMMAL COLLEGE, SIVAKASI.

2. GENOME SEQUENCING:
GENOME:
The complete set of genes of an organism.
SEQUENCING:
Arrangement of nucleotide base pairs.

3. HUMAN GENOME PROJECT(HGP):
It is a project to map and sequence the
3 billion nucleotides contained in the genome
and to identify all the genes present in it.

4. The HGP was officially launched in US in
1990,15 years effort sponsored by the
NATIONAL INSTITUTES OF HEALTH AND
DEPARTMENT OF ENERGY. Sequencing
centers in china france, germany , japan and UK.

5. HIERARCHIAL SHOT
GUN SEQUENCING:
The HUMAN GENOME PROJECT used
hierarchial shot gun assembly to sequence the human
genome.

7. REQUIREMENTS:
DNA(from blood sample).
Restriction endonucleases.(EcoR1)
BAC(Bacterial artificial chromosome.)
Eschierichia coli

8. BAC (Bacterial Artificial
Chromosome):
Artificial chromosome it is a vector that can
carry larger DNA fragments.(300Kb)
BAC also a vector to artificially carry DNA into
the cell of a bacterium Escherichia coli to make a
BAC clone.

10. DNA isolated from blood sample from unknown person.
Digested with restriction endonucleases(BAMH1,ECOR1)
pieces between 100kb-200kb length were inserted in BAC.
The recombinant BAC collection is known as BAC library
.
BAC library stored in freezer condition.
Whenever it was needed that was used.

12. BAC inserting method:
Each BAC insert had to be assigned to a
specific location in human genome. one way to
accomplish this task is to match unique landmark in
the human genome with the same landmark in an
insert. there are 2 landmark:
protein coding gene.
Recombinant DNA technology.

13. LANDMARK:
Any short piece of DNA with a unique
sequence and a known chromosomal location
can serve as a landmark. thousands of such
Short (200-500bp) unique sequence called
sequence tagged sites(STS).

14. BAC Insert method:
BAC inserts were also ordered by restriction
fingerprint analysis as follows.
BAC inserts were digested with a restriction
endonucleas and the resulting fragments separated by gel
electrophoresis.
If electrophoretic patterns produced by different
BAC clones had bands in common then the inserts were
likely to contain overlapping fragments.

15. DNA from each selected BAC clones was purified, subjected
to shotgun sequencing and contigs assembled.
A single capillary DNA sequencer handled about 40000
fragments in a day(1990).
In 1999 the sequencing center at MIT sequenced and
processed about 1,20,000 fragments per day most routine
work was done robotically.

17. HUMAN GENOME:
A. The human genome has a total of 3164.7
million nucleotide bases.
B. The total number of genes is estimated to
be 30,000.
C. The functions of over 50% of discovered
genes are not known.
D. The average gene consists of 3000 bases.
However, the largest gene is dystrophin made of 2.4
million bases.

18. E. A large portion of the human genome is
made of repeated sequences.
F. Chromosome 1 has the maximum number of
genes (2968) and the Y has the least (231).

19. The Human Genome Project
Advantages:
Predict and prevent diseases:
By knowing which genes predispose people to
particular conditions, doctors will be able to predict which people are
likely to suffer from a particular disease and offer a preventive course
of action, which may involve medical treatment or lifestyle changes.
Furthermore, cures could be found for genetic diseases like cystic
fibrosis or sickle cell anaemia.
.

20. Improved medicine:
Personalized medicines can be developed based
on the way our individual bodies react to the disease and the
treatments, which will be more effective because the
medicines will be tailored for our specific medical needs.

21. Accurate diagnoses:
Doctors can develop more accurate diagnostic techniques for
certain conditions which are difficult to diagnose at an early stage
Improve forensic science:
Genetic fingerprinting helps to match a suspect to the biological
material found at a crime scene. In the future it could be possible to
figure out what a suspect looks like from DNA found at a crime scene
e.g. their eye, hair and skin colour.

22. Disadvantages:
Increased stress:
People could be diagnosed with illnesses that they are
suspectible to develop in the future and spend their life worrying
about it even before they get it.
Geneism:
People with genetic problems could be under pressure not
to have children as a threat of passing on their faulty genes onto
the next generation.

25. Benefits:
The potential benefit of a comprehensive sequencing
effort was highlighted by the isolation of disease-linked
genes such as Huntington's disease, Cystic Fibrosis, and the
most common breast-cancer-associated gene, BRCA1.
But most common human diseases are genomic -
"polygenic" diseases caused by multiple genes spread
diffusely throughout the human genome. Cancer and mental
illnesses are examples of genomic diseases.

26. Thank you…