Genomics is the study of whole genomes. In the 1980s, scientists determined sequences of important genes. In the 1990s, the genome of H. influenzae was fully sequenced. The Human Genome Project, begun in 1990, fully sequenced the human genome ahead of schedule in 2003. The human genome contains 3.2 billion DNA base pairs and 30,000-40,000 genes. While genomics provides medical benefits, it also raises safety, ethical, and privacy concerns that remain open questions.

1. GENOMICS
The science of studying
whole genomes.

2. Genomics
• (1980s) the nucleotide sequences of many
important genes from human and other
organisms had been determined.
• (1990s) a team of scientists determined
the nucleotide sequence of the entire
genome of Haemophilus influenzae.
• The first targets of genomics research
were pathogenic bacteria.

3. The Human Genome Project
• (1990) an international consortium of
government-funded researchers began
the Human Genome Project.
• (April 14, 2003) the Human Genome
Project was successfully completed more
than 2 years head of schedule.

4. The Human Genome Project
• The 24 different kinds of chromosomes in
the human genome (22 autosomes plus
the X and Y chromosomes) contain
approximately 3.2 billion nucleotide pairs
of DNA and 30,000 to 40,000 genes.
• Most complex eukaryotes have huge
amount of noncoding DNA – about 97% of
human DNA is made up of gene control
type.

5. The Human Genome Project
• The remaining DNA has been called “junk
DNA”, a tongue-in-cheek way of saying
that scientists don’t understand its
functions.
• Much of the DNA between genes consists
of repetitive DNA.

6. The Human Genome Project
Repetitive DNA
Nucleotide sequences present in many copies
in the genome.
Main Types:
5. A unit of just a few nucleotide pairs is repeated
many times in a row.
6. Each repeated unit is hundreds of nucleotides
long and the copies are scattered around the
genome.

7. Tracking the Anthrax Killer
• (October 2001) Bob Stevens, a 63-year-old
editor at a Florida media company, died from
inhalation anthrax, a disease caused by
breathing spores of the bacterium Bacillus
anthracis.
• Examining the genomes of the spores could
answer several crucial questions.
• Investigators compared the genomes – which
were 3 million nucleotides long – of the mailed
anthrax spores with several laboratory strains.

8. Tracking the Anthrax Killer
• They were able to match the deadly spores with
a laboratory subtype called the Ames strain.
• The Ames strain was first isolated from a dead
Texas cow in 1981.
• The samples were sent to U.S. Army Medical
Research Institute in Fort Detrick, Maryland.
• From there, it was sent to at least 14 other labs
for use in experiments.

9. Tracking the Anthrax Killer
• Unfortunately, the date were not detailed
enough to tie the mailed samples to any
particular laboratory.
• The anthrax investigation is a prominent
example of the new field of comparative
genomics, the comparison of whole
genomes.

10. Genome-Mapping Techniques
Genetic (Linkage) Mapping
• Scientists combined pedigree analysis of large
families with DNA technology to map over 5,000
genetic markers.
• These markers included both coding regions
(genes) and noncoding regions (such as strands
of repetitive DNA).
• The low-resolution genetic map provided anchor
points that enabled researchers to map other
markers by testing for genetic linkage to the
known markers.

11. Genome-Mapping Techniques
Physical Mapping
• Researchers used several different restriction
enzymes to break the DNA of each chromosome
into a number of identifiable fragments, which
they cloned.
• They then determined the original order of the
fragments in the chromosome by overlapping
the fragments and matching up their ends.
• They used probes to relate the fragments to the
markers mapped in stage 1.
• The end result was a series of DNA segments
that spanned the genome in a known order.

12. Genome-Mapping Techniques
DNA Sequencing
• As the sequence of each cloned fragment
from the physical map of stage 2 was
determined, the fragments were
reassembled in their proper order,
producing large-scale sequences.

13. Genome-Mapping Techniques
The Whole Genome Shotgun Method
• The procedure essentially skips the first two
stages described and proceeds directly to the
third.
• An entire genome is chopped by restriction
enzymes into fragments that are cloned and
sequenced.
• High-performance computers running
specialized mapping software can reassemble
the millions of partial sequences into a entire
genome.

15. HUMAN GENE THERAPY
A recombinant DNA procedure that
seeks to treat disease by altering an
afflicted person’s genes.

16. Human Gene Therapy
1. A gene from a normal individual is
isolated and cloned by recombinant DNA
techniques.
2. The gene is inserted into a vector, such
as a nonharmful virus.
3. The virus is then injectedto the patient.

17. Treating Severe Combined
Immunodeficiency
Severe Combined Immunodeficiency (SCID)
A fatal inherited disease caused by a
single defective gene.

18. Treating Severe Combined
Immunodeficiency
• The first trial of began at the National Institutes
of Health in 1990 on a 4-year-old girl with SCID.
• Immune system cells were periodically removed
from her blood, infected with a virus engineered
to carry the normal allele of the defective gene,
then reinjected into her bloodstream.
• Her gene therapy lasted a limited time and was
only one of the several treatments she received.

19. SAFETY
AND
ETHICAL ISSUES

20. The Controversy Over
Genetically Modified Foods
• Advocates of a cautious approach fear
that crops from other species might be
hazardous to human health or harm the
environment.

21. Ethical Questions Raised by
DNA Technology
• DNA technology raises many questions –
moral, legal, and ethical – few of which
have clear answers.
• Advances in genetic fingerprinting raise
private issues.
• There is a danger that information about
disease-associated genes could be
abused.

22. Ethical Questions Raised by
DNA Technology
• Should we try to eliminate genetic defects in our
children and their descendants?
• Should we interfere with evolution this way?
• Are we willing to risk making genetic changes
that could be detrimental to our species in the
future?
• How do we really feel about wielding one of
nature’s singular powers – the ability to make
new microorganisms, plants, and even animals?