Quiz 9 Flashcards
Forensic science
Use of technology and science to help solve criminal and civil cases
DNA profiling
Identifying individuals using various types of DNA approaches (obtaining a DNA profile from a sample then comparing it another sample)
Profiling minisatellites
VNTRs are 15-100 bp long with a locus that contains up to 30 different alleles (based on how many repeats it contains); different people can have different VNTR alleles, so length of locus varies between different individuals
Method of profiling minisatellites
Extract DNA, restriction enzyme cuts om either side of the repeats, add agarose gel, and examine
Limitations of minisatellites
Requires a large amount of cells (10,000) and DNA must be fairly intact; good for paternity testing
Profiling microsatellites
STRs: each 2 to 9 bp long and repeated between 7 and 40 times; a locus; just like VNTRs different individuals have different length STR alleles at a given loci
Method of profiling microsatellites
FBI uses 20 STR loci core set; analysis is PCR based so trace samples can be used, making it choice method of DNA profiling; DNA is extracted, PCR uses primers with different colors that flank STR loci, capillary electrophoresis, analyze data using a computer to calculate size and quantity of fragments
Result: heterozygous loci make double peaks and homozygous loci single peaks
Profiling y-chromosome microsatellites
20 STR loci on the Y-chromosome that are used to ID male suspects (paternally inherited)
Limitations: can’t distinguish males with same Y-chromosome
Additional application: identify a missing person if a male relatives DNA is available for comparison
Profiling mitochondrial DNA
(mtDNA) Each human cell has 200 to 1,700 mitochondria, which are maternally inherited, so PCR to amplify portions of mtDNA, DNA sequence PCR products, and compare these DNA sequences
Useful cause only a small sample is needed, including old degraded samples, but limited because can’t tell maternal relatives apart
DNA phenotyping
Using a DNA sequence to predict phenotypes and ancestral origins by using SNP patterns to predict a suspects appearance, biological sex, geographic ancestry
Interpreting DNA profiles
Use DNA profile and compare with a sample from a crime scene or profiles in a database, and if positive match is found use statistical methods to calculate probability (more loci the better)
Issue: identical twins and close relatives
DNA profile databases
Combined DNA index system (CODIS) maintained by FBI, and some states have own databases
Limitations on DNA forensics
Most cases have no DNA evidence, in some cases DNA evidence hasn’t been analyzed, human error, crime scene samples often have mixed DNA from multiple sources, degraded DNA is difficult to analyze, criminals might introduce biological samples, DNA that matches STR loci of an individual can be synthesized
Ethical considerations of DNA forensics
Collection and storage of biological samples and DNA profiles, familial DNA testing
Genetic engineering
Changing an organism’s genome
Biotechnology
Using living organisms to create products to help improve quality of life
Biopharmaceutical products
Pharmaceutical products produced by means of biotechnology such as therapeutic proteins (most successful application of recombinant DNA tech)
Biopharming
Production of proteins in genetically modified plants and animals
Examples of biophamraceutical products
Pancreatic cells make preproinsulin, which is processed to produce mature insulin; in 1982 Genentech produced insulin in bacteria; there was an issue of bacteria not being able to process and modify eukaryotic proteins, so eukaryotic hosts were used
Bioreactors
(Biofactories) “living factories” such as goats that produce antithrombin, an antiblood clotting protein, using a vector to make it be produced in their milk, or using hens that produce egg whites containing sebelipase alfa to treat lysosomal illness
Vaccine production
Instead of just inactivated vs attenuated, genetically engineered vaccines called subunit vaccines use surface proteins from a pathogen, or DNA-based vaccines inject a plasmid with protein encoding pathogen gene to individual so the protein is expressed, causing an immune response
Using plants to produce vaccine proteins
Plants are easy to grow and cheap; ex. Express the antibodies for ebola found in mice in tobacco leaves; edible plant vaccines such as a banana or potato (cost less, easy, no needles, but difficult to determine how much a person gets, and will the vaccine pass through unaltered?)
Agricultural biotechnology
Creating transgenic plants that have desired traits; i.e. improving growth characteristics and yield, increasing nutritional value, and providing crop resistance against insect and viral pests, drought, and herbicides
Reasons for producing transgenic animals
To study gene function; development if transgenic farm animals (i.e. growth hormone to make bigger, bioreactors, protecting animals from pathogens, cow with hypoallergenic milk, CRISPR-Cas to make animals with bigger muscles, etc)