Genomics

Overview of Genomics
  - The term genome refers to the total genetic composition of an organism.
  - The term genomics refers to the molecular analysis of the entire genome of a species.
  - Major activities in genomics include:
    - Mapping: Determining the locations of sites, such as genes, along a chromosome.
    - DNA Sequencing: Determining the entire base sequence of a genome, which is usually millions to billions of base pairs in length.

Key Terms:
  - High-throughput: Refers to technologies that enable rapid sequencing of large amounts of DNA.
  - Comprehensive: Involves a thorough and complete approach to genomics.
  - Highly Parallel: Techniques that allow simultaneous execution of numerous sequencing runs.
  - Miniaturization: The process of creating smaller and more efficient instruments in genomic technologies.
  - Robotics and Automation: Use of advanced robotics for conducting genomic research efficiently.
  - Informatics: The application of data analysis and management in genomics.

Pioneering Projects:
  - In 1995, researchers, including Craig Venter and Hamilton Smith, obtained the first complete DNA sequence of an organism:
    - Haemophilus influenzae (a bacterium).
  - In 1996, the genome of the first eukaryote, Saccharomyces cerevisiae (baker’s yeast), was completed.
    - This genome contains 16 linear chromosomes and approximately 12.1 million base pairs comprising around 6,300 genes.

Purpose of Genome-Sequencing Projects:
  - Aim to determine the DNA sequence of the entire genome of a species.
  - These projects involve large interdisciplinary teams of scientists.
  - Since 1995, there has been remarkable progress in our ability to carry out genome projects.

Establishment and Goals:
  - In 1988, the NIH established the Office of Human Genome Research, and in 1990, the Human Genome Project officially began under the direction of James Watson.
  - The HGP was the largest internationally coordinated research effort in biological history.
  - Goals of HGP included:
    1. Obtain a genetic linkage map of the human genome.
    2. Create a physical map of the human genome.
    3. Sequence the entire human genome.
    4. Develop technology for managing human genome information.
    5. Analyze genomes of model organisms.
    6. Address ethical, legal, and social implications from the results.
    7. Advance methodologies in genetics.

Size and Complexity:
  - The challenge of sequencing genomes due to the size of DNA:
    - E. coli Genome:
      - Total base pairs: 4,000,000
      - Estimated sequencing runs calculation:
        - $ext{4,000,000 (bases)} imes 7 = 28,000,000$
        - $rac{28,000,000}{500} = 56,000$ sequencing runs required.
    - Human Genome:
      - Total base pairs: 3,000,000,000
      - Estimated sequencing runs calculation:
        - $ext{3,000,000,000 (bases)} imes 7 = 21,000,000,000$
        - $rac{21,000,000,000}{500} = 42,000,000$ sequencing runs required.
    - Previous sequencing technology could generate about 500 bases per run.

Funding the HGP:
- Estimated cost of the Human Genome Project was around $3 billion.
Justifications for costs include:
  - Scientific Discovery
  - Technological Advances
  - Benefits for Human Health
  - Economic Impact
  - Improving Agriculture

Cost Reduction:
- The cost of sequencing a human genome has dropped from $3 billion in the 1990s to currently $600 or less with results typically available in one to two days.
High-throughput Sequencing:
- Rapidly sequencing large quantities of DNA through advanced technologies.
- Breakthroughs leading to this efficiency include automated sequencing with fluorescence detection.

Parallel Sequencing:
- Simultaneous performance of many sequencing runs using multiple gel-filled capillary tubes.
Next-Generation Sequencing (NGS):
- Capable of processing thousands to millions of sequence reads in parallel.
Third-Generation Sequencing:
- Methods that sequence single DNA molecules used long-read sequencing approaches.

Sequencing Approaches:
  - The U.S. HGP began as a clone-by-clone project focusing on developing a physical map.
  - In 1998, Celera Corporation implemented a whole-genome shotgun sequencing approach speeding up the sequencing process.
  - The project was completed four years ahead of schedule, but the draft sequences had gaps.

Launch:
  - The 1000 Genomes Project was initiated in 2008 to establish a detailed understanding of human genetic variation.
  - The project aimed to determine the DNA sequence of at least 1000 anonymous participants worldwide.
  - By 2012, sequencing of 1092 genomes was published in the journal Nature, leading to thousands more human genomes sequenced thereafter.

Research Areas for Genome Sequencing:
  1. Basic Research: Cloning and characterizing genes.
  2. Medicine: Identifying genetically involved diseases and studying genes in infectious organisms.
  3. Agriculture: Development of new organism strains with improved traits.
  4. Evolution: Using comparative genomics to analyze relationships among species.

Overview of Genomics:
- Knowledge of the genome includes understanding the transcriptome and proteome — variations beyond just genes, with each organism having potentially numerous transcriptomes and proteomes, emphasizing the developmental complexity of genomics.