The Human Genome Project
Introduction
•
Until the early 1970’s, DNA was the most
difficult cellular molecule for biochemists to
analyze.
•
DNA is now the easiest molecule to analyze
– we can now isolate a specific region of the
genome, produce a virtually unlimited
number of copies of it, and determine its
nucleotide sequence overnight.
Molecular Biology Of The Cell. Alberts et al. 491-495
Introduction
•
At the height of the Human Genome
Project, sequencing factories were
generating DNA sequences at a rate of 1000
nucleotides per second 24/7.
•
Technical breakthroughs that allowed the
Human Genome Project to be completed
have had an enormous impact on all of
biology…..
Molecular Biology Of The Cell. Alberts et al. 491-495
Human Genome Project
Goals:
■ identify all the approximate 30,000 genes in human DNA,
■ determine the sequences of the 3 billion chemical base pairs that make up human
DNA,
■ store this information in databases,
■ improve tools for data analysis,
■ transfer related technologies to the private sector, and
■ address the ethical, legal, and social issues (ELSI) that may arise from the project.
Milestones:
■ 1990: Project initiated as joint effort of U.S. Department of Energy and the National
Institutes of Health
■ June 2000: Completion of a working draft of the entire human genome (covers >90%
of the genome to a depth of 3-4x redundant sequence)
■ February 2001: Analyses of the working draft are published
■ April 2003: HGP sequencing is completed and Project is declared finished two years
ahead of schedule
U.S. Department of Energy Genome Programs, Genomics and Its Impact on Science and Society, 2003
What does the draft human
genome sequence tell us?
By the Numbers
•
The human genome contains 3 billion chemical nucleotide bases (A, C, T, and G).
• The average gene consists of 3000 bases, but sizes vary greatly, with the largest
known human gene being dystrophin at 2.4 million bases.
• The total number of genes is estimated at around 30,000--much lower than
previous estimates of 80,000 to 140,000.
• Almost all (99.9%) nucleotide bases are exactly the same in all people.
• The functions are unknown for over 50% of discovered genes.
U.S. Department of Energy Genome Programs, Genomics and Its Impact on Science and Society, 2003
What does the draft human
genome sequence tell us?
How It's Arranged
•
The human genome's gene-dense "urban centers" are predominantly composed of
the DNA building blocks G and C.
• In contrast, the gene-poor "deserts" are rich in the DNA building blocks A and T.
GC- and AT-rich regions usually can be seen through a microscope as light and dark
bands on chromosomes.
