Other names for DNA chips:
- SNP chips
- Biochips
- DNA microarrays
- Gene arrays
- Microarray chips
- Affymetrix, Inc. has patented a DNA chip with its own trademark, Gene chip
SNPs and CNPs:
- account for 0.4% differences in human DNA sequences; (human DNA sequences are 99.6% the same!)
- SNPs (small variations) account for 80% of the differences
- CNPs (larger variants) account for 20% of the differences
SNPs:
- single nucleotide polymorphisms (variation in a population as a result of only one DNA base being different in a sequence)
- 3,750,000 in the average person
- Haplotype Maps (HAPMAP) show locations/addresses of SNPs in a human's
DNA sequence
- frequently occurring SNPs cause common diseases; people who share a common disease have identical sets of SNPs that differ from those in people who do not have the disease
- responsible for variation in human personality
- cause Neuropsychiactric Disorders
- DNA chips are used to locate them
Composition of DNA chips:
- made of glass
- comprised of DNA base sequences/oligonucleotide arrays that were created in a labratory
-microarray chips: arrays are 200 microns in diameter
-macroarray chips: arrays are 300 microns in diameter
-Probes: DNA fragments read
5' to 3' have known locations and
sequences
-Unknown DNA segments are
read 3' to 5' and have neon labels
How DNA chips work:
- clearly-labeled probes (50-50,000 bases)
are placed either manually or robotically
over glass chip of unknown segments
with the known fragments to form
a double helix via complementary base pairing
and hybridization (hydrogen bond connection)
- Laser scanner analyzes the neon (unknown)
segments on the double helix to determine the
previously unknown locations of these SNP sequences
How DNA chips help:
used to only be able study
study one gene at a time
organism's entire genome
and thus allow biologists
to study multiple genes
simultaneously
Functions of DNA chips:
- expose the presence of a person's genes for certain traits, diseases, and disorders
- show the DNA sequences that code for specific genes, so scientists can recognize gene
mutations and pinpoint the causes of traits, diseases, and disorders
- allow scientists to determine the frequency of a specific gene within a population
- explain why some drugs work well in some people, but not others based on their
genetic make-up
- show how some genes alter themselves in response to contact with specific toxicants
Research:
-began in 2008
-scientists from the United States, Germany, China, and the United Kingdom
-studied locations of SNPs and CNPs
-in the process of formulating a catalog that includes all variants in human beings
-study individual genomes of 2,000 diverse anonymous people
-provide a resource for researchers working with DNA chips and other medical studies
Cost of tests:
- entire genome: currently $25,000
- certain SNPs that cause common diseases and disorders: currently $1,000
- researchers and scientists predict that as time passes, DNA chips will become cheaper and more accessible
- entire genome: $1,000 in 2014; $100 in 2020
Where will DNA chips be kept?
- needs to be extremely secure
- in a personal safe at home?
- in a vault at the bank?
- pre-determined by testing companies? accessible at all times or only on specific occassions?
Job Discrimination:
- employers might pay for or force prospective
employees to include a copy of their (and their family's)
genome(s) with their resume
-might base decision on whether the person or a loved one
will have a future disorder or disease that could inhibit
work performance
Who gets to know your genome?
- Do you have to share this information with your spouse, family, the government, employers, insurance companies, friends, etc.?
- potential to violate privacy
Violate a Person's Right to Ignorance of the Future:
- make it more difficult for one to live in present
- more anxiety and worry if you know that you or a loved one will suffer from a specific disease or disorder in the future
- potential to heighten use of harmful coping mechanisms (i.e. alchoholism, drug abuse, suicide, etc.)
- violate natural course of life
- some religions might view DNA chips as an attempt to replace God or a higher power because now humans are "all-knowing" too
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Types of DNA chips:
comprised of thousands of oligonucleotide array (DNA base) sequences
microarray chips: arrays are 200 microns in diameter
macroarray chips: arrays are 300 microns in diameter
Genetic Discrimination:
- insurance companies might drop or charge extremely high rates for those people who have serious diseases or disorders in their future