Human Genome Project

Examples of Human Genome Project in the following topics:

• Basic and Applied Science

  • Another example of the link between basic and applied research is the Human Genome Project, a study in which each human chromosome was analyzed and mapped to determine the precise sequence of DNA subunits and the exact location of each gene.
  • (The gene is the basic unit of heredity; an individual's complete collection of genes is his or her genome. ) Other less complex organisms have also been studied as part of this project in order to gain a better understanding of human chromosomes.
  • The Human Genome Project relied on basic research carried out with simple organisms and, later, with the human genome.
  • The Human Genome Project was a 13-year collaborative effort among researchers working in several different fields of science.
  • The project, which sequenced the entire human genome, was completed in 2003.

• Predicting Disease Risk at the Individual Level

  • Genome analysis is used to predict the level of disease risk in healthy individuals.
  • The introduction of DNA sequencing and whole genome sequencing projects, particularly the Human Genome project, has expanded the applicability of DNA sequence information.
  • Genomics is now being used in a wide variety of fields, such as metagenomics, pharmacogenomics, and mitochondrial genomics.
  • The scientists used databases and several publications to analyze the genomic data.
  • Explain how analysis of an individual's genome can aid in predicting disease risk

• DNA Sequencing Techniques

  • The Sanger sequencing method was used for the human genome sequencing project, which was finished its sequencing phase in 2003, but today both it and the Gilbert method have been largely replaced by better methods.
  • When the human genome was first sequenced using Sanger sequencing, it took several years, hundreds of labs working together, and a cost of around $100 million to sequence it to almost completion.
  • Many researchers have set a goal of improving sequencing methods even more until a single human genome can be sequenced for under $1000.
  • Most genomic sequencing projects today make use of an approach called whole genome shotgun sequencing.
  • Genome sequencing will greatly advance our understanding of genetic biology.

• Uses of Genome Sequences

  • Almost one million genotypic abnormalities can be discovered using microarrays, whereas whole-genome sequencing can provide information about all six billion base pairs in the human genome.
  • Genomics is still in its infancy, although someday it may become routine to use whole-genome sequencing to screen every newborn to detect genetic abnormalities.
  • It sounds great to have all the knowledge we can get from whole-genome sequencing; however, humans have a responsibility to use this knowledge wisely.
  • Otherwise, it could be easy to misuse the power of such knowledge, leading to discrimination based on a person's genetics, human genetic engineering, and other ethical concerns.
  • DNA microarrays can be used to analyze gene expression within the genome.

• Use of Whole-Genome Sequences of Model Organisms

  • Sequencing genomes of model organisms allows scientists to study homologous proteins in more complex eukaryotes, such as humans.
  • Several other organelle and viral genomes were later sequenced.
  • Genomes of other model organisms, such as the mouse Mus musculus, the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, and the human Homo sapiens are now known.
  • Research on many proteins that are important to humans is done by examining their homologs in yeasts.
  • Saccharomyces cerevisiae, a yeast, is used as a model organism for studying signaling proteins and protein-processing enzymes which have homologs in humans.

• Noncoding DNA

  • For example, over 98% of the human genome is noncoding DNA, while only about 2% of a typical bacterial genome is noncoding DNA.
  • More than 98% of the human genome does not encode protein sequences, including most sequences within introns and most intergenic DNA.
  • For example, the genome of the unicellular Polychaos dubium (formerly known as Amoeba dubia) has been reported to contain more than 200 times the amount of DNA in humans.
  • The pufferfish Takifugu rubripes genome is only about one eighth the size of the human genome, yet seems to have a comparable number of genes; approximately 90% of the Takifugu genome is noncoding DNA.
  • About 80 percent of the nucleotide bases in the human genome may be transcribed, but transcription does not necessarily imply function.

• Biotechnology

  • Relying on the study of DNA, genomics analyzes entire genomes, while biotechnology uses biological agents for technological advancements.
  • Genomics is the study of entire genomes, including the complete set of genes, their nucleotide sequence and organization, and their interactions within a species and with other species.
  • The advances in genomics have been made possible by DNA sequencing technology.
  • These findings have helped anthropologists to better understand human migration and have aided the field of medicine through the mapping of human genetic diseases.
  • The ways in which genomic information can contribute to scientific understanding are varied and quickly growing.

• Variations in Size and Number of Genes

  • The C-value is another measure of genome size.
  • For example, the predicted size of the human genome is not much larger than the genomes of some invertebrates and plants, and may even be smaller than the Indian rice genome.
  • In humans, more proteins are encoded per gene than in other species.
  • In eukaryotic organisms, there is a paradox observed, namely that the number of genes that make up the genome does not correlate with genome size.
  • This figure represents the human genome, categorized by function of each gene product, given both as number of genes and as percentage of all genes.

• Genome Evolution

  • There are various mechanisms that have contributed to genome evolution and these include gene and genome duplications, polyploidy, mutation rates, transposable elements, pseudogenes, exon shuffling and genomic reduction and gene loss.
  • The most common transposable element in the human genome is the Alu sequence, which is present in the genome over one million times.
  • Often cited examples of pseudogenes within the human genome include the once functional olfactory gene families.
  • Over time, many olfactory genes in the human genome became pseudogenes and were no longer able to produce functional proteins, explaining the poor sense of smell humans possess in comparison to their mammalian relatives.
  • Good examples are the genomes of Mycobacterium tuberculosis and Mycobacterium leprae, the latter of which has a dramatically reduced genome.

• Strategies Used in Sequencing Projects

  • The strategies used for sequencing genomes include the Sanger method, shotgun sequencing, pairwise end, and next-generation sequencing.
  • The basic sequencing technique used in all modern day sequencing projects is the chain termination method (also known as the dideoxy method), which was developed by Fred Sanger in the 1970s.
  • This was sufficient for sequencing small genomes.
  • However, the desire to sequence larger genomes, such as that of a human, led to the development of double-barrel shotgun sequencing, more formally known as pairwise-end sequencing.
  • Compare the different strategies used for whole-genome sequencing:  Sanger method, shotgun sequencing, pairwise-end sequencing, and next-generation sequencing