Intro Video
Responses and Discussion Points
- The human genome is about 3 billion base pairs of DNA. Each base pair consists of one of four different types of molecules with the symbols A, C, G, and T. Various parts of the genome contain information about various traits of the organism.
- Around 30 years ago, laboratories could sequence tens of base pairs of DNA per day. We can now sequence hundreds of billions of base pairs of DNA per day with a single machine.
- Important concepts for this question include: (1) that the genome provides fundamental information about how an organism is built; (2) that sequencing the genome is extremely efficient and relatively inexpensive now; (3) that all this data can be systematically collected; and (4) that the information can be used to figure out how traits are determined from the bottom up as opposed to the top-down approach previously used (i.e., previously scientists started from the traits and tried to figure out what DNA sequences coded for those traits).
Additional Resources
Timeline of the Human Genome: https://unlockinglifescode.org/timeline?tid=4
About the Human Genome Project: http://www.genome.gov/25019879
Agriculture and Food
Responses and Discussion Points
- They would wait until the plants grew and produced fruit or vegetables. Farmers would cross parent plants that produced offspring with desirable traits, expecting at least some of the offspring of these crosses to also have these traits.
- Knowing which genes control which traits allows you to look directly at the DNA of an organism to see if it has these genes. You don’t have to wait until an organism shows these traits physically (has this “phenotype”), which can take a while if you are interested in things like whether cows produce a lot of milk or trees produce pest-resistant fruit. You just need to have a sample of DNA from the organism to see if it has the gene that encodes the trait you want, and you can take that sample early in the organism’s life span (e.g., taking a sample from a calf rather than waiting to see how much milk an adult cow produces).
- Gene chippers take a tissue sample from a seed to extract and sequence the DNA so it can be sorted into having either desirable genes (which will help the seed get sold/planted) or not. The chippers do not destroy any part of the seed needed for germination. Once you know which seeds carry the genes you want, the seeds are still viable and can be sold and planted.
- Gene chippers increase the speed of selection because you don’t have to wait until the seeds grow into adult plants to see whether the plants will have the traits you want. Because they are automated, gene chippers also take samples and process them much faster than humans could do by hand.
Additional Resources
Explanation and videos about plant breeding and gene chippers used by Monsanto (Monsanto.com): http://www.monsanto.com/products/pages/breeding.aspx
How gene chippers speed up plant selection (AgAdvance.com): http://www.agadvance.com/issues/jan-2013/monsantos-seed-chipping-technology.aspx
Society and Ethics Resources
Are you in favor of genetically modifying foods? Do you think it is OK to use genomic technologies to speed up the same breeding processes that have been used since humans started farming and domesticating animals?
http://www.popsci.com/science/article/2011-01/life-cycle-genetically-modified-seed?image=0
DNA Barcoding
Responses and Discussion Points
- “DNA barcoding” is a shorthand term to describe the technologies that make it possible to identify the species of an organism from the sequence of nucleotide bases in a small region of its DNA. Each species has a unique order of nucleotide bases in this particular genetic region that can be used to identify individuals belonging to this species.
- DNA fingerprints identify individuals; the DNA in the region tested for fingerprinting is highly variable among individuals. Barcodes are highly variable among species but identical within individuals of the same species. Barcodes can thus be used to identify species. You could use fingerprinting to determine which boy from the village left parts of his flesh on the barbed wire fence, but you would need barcoding to determine that the flesh came from a boy and not a wolf.
- Future DNA barcode scanners will need to be simple, cheap, and reusable. By comparing them to a comb, he indicates that they should also be small and easily portable.
- DNA barcoding provides a way to record the many different species on Earth and to identify unknown organisms. This catalog of organisms provides a foundation to study and conserve these organisms.
Additional Resources
The International Barcode of Life project (iBOL): http://ibol.org/
iBOL’s explanation of DNA barcoding: http://ibol.org/about-us/what-is-dna-barcoding/
Barcode of Life Data Systems (BOLD) database: http://www.boldsystems.org/
BOLD Student-Data Portal (classrooms can contribute to the BOLD database): http://www.boldsystems.org/index.php/SDP_Home
Barcoding biodiversity (Michael Gross, Current Biology 22(3), 2012, pp R73-R76): http://www.sciencedirect.com/science/article/pii/S0960982212000668
Clinical Genomics
Responses and Discussion Points
- Sequencing the genomes of many different people allows us to understand what parts of the genome are similar among all individuals, what parts are different, and how those differences matter. Some of these genomic differences will not cause any known phenotypic (observed) difference in the individuals that have them, while some will cause differences like eye and hair color and still others will affect whether an individual is healthy or sick. Having many different genomes to compare allows experts to know what is within a normal level of variation. They can then determine whether any abnormalities in genomic regions are problematic for health.
- Some potential problems that could arise from using genomic information to make diagnosis and treatment decisions include effects on other at-risk family members (who may have the same genes but not know it), limited information from genetic tests (a test may provide information on the risk of developing a disease but not on the severity or quality of life), the ability to use genetic information to make decisions about reproduction or to terminate pregnancies, the potential for insurance companies or employers to discriminate against individuals based on genomic testing (privacy), and equitable access to genomic medicine (access for the poor and in developing countries).
- Students share their own opinions.
Additional Resources
National Human Genome Research Institute Genomic Medicine FAQ: http://www.genome.gov/27552451
Cold Spring Harbor Laboratory ELSI of Genome Research: http://cshl.libguides.com/content.php?pid=357987&sid=2928013
World Health Organization Human Genetics programme ELSI of human genomics: http://www.who.int/genomics/elsi/en/
Discovering the Genome
