Sorting and Analyzing DNA
• gel electrophoresis is used to separate molecules according to mass
and charge
• used to separate fragments of DNA
• TO BEGIN
• Solution containing DNA is apllied to one end of a gel
electrophoresis
• Electric current is added so one end has positive and one end has a
negative charge
• DNA is negative so will migrate toward positive end of the gel
• Smaller fragment move more quickly so will travel farther.
• Fragment form a pattern of bands called a DNA fingerprint
• Restriction enzymes and gel elctrophoresis help
researchers analyze and compare DNA samples
• Ex #1. Forensics (DNA sample from a crime scene can be
cut with restriction enzymes and turned into a DNA
fingerprint that can be compared to possible suspects DNA
fingerprints to identify a match.
• Ex #2. Parentage.
• Do a Venn Diagram for RNA and DNA
Genetics and Society
Section 18.4
Biotechnology
• Using natural biological systems to create new technologies and
products
• Computers store enormous amounts of genetic information (gene
banks, DNA libraries)
• Potential to change the way we live:
• Diagnose and treat diseases, food, industries, air we breathe
PCR
• Polymerase Chain Reaction
• Used to make many copies of a specific strand of DNA VERY quickly!
• ANIMATION
Gathering and managing Genetic information
• DNA microarray
• Chip with a grid of thousands of microscopic cells
• Each cell contains a nucleic acid that can bind with one mRNA
molecule transcribed during gene expression
The microarray is scanned and analyzed to compare the
pattern of gene expression in each cell sample
• can analyze thousands of genes at the same time
• Genes in same cell in different environments
• Pinpoint genes reponsible for a particular function,
interections among genes, relationship between
envirnoment and gene expression
ANIMATION
STEM CELLS
• Stem Cell School
Public Benefits of Genetic Research
• Human medicine
• Developing drugs tailored to particular gene expression associated
with particular disorders and unique human genome
• All research about Human Gnome project is public
Ownership of Genetic Information
• Who owns volunteered DNA
• Genographic Project
Patenting organisms and genes
• Roundup-Ready canola
• Resistant to herbicide Roundup
• Patented by Monsanto, who controls how it can be used, so they can
make a profit
• Concerned farmers
• What happens with breast cancer gene?
Biotechnology Products
• We know how to import foreign DNA into bacteria, when it is
imported into plants and animals it produces a transgenic organism.
• Uses for biotechnology products…..
Medicinal Bacteria
• Human insulin synthesized by transgenic bacteria
• Why bacteria?
• Bioremediation – using living cells (bacteria) to clean
up environment:
• oil spills, remove heavy metals from water, remove
polychlorinated biphenyls (PCBs) from soil
Transgenic Plants
• ½ crop plants are transgenic to become more resistant to herbicides,
insect pests, and viruses
• Plants can be more tolerant of drought and colder temperatures
• Higher yields
• Also can be more nutritious
• Ie. rice
Cloned and Transgenic Animals
• Clones- genetically identical (twins), arise naturally in nature
• Researcher Ian Wilmut successfully cloned a a sheep, Dolly, from and
adult somatic cell.
• Clones have a higher mortality rate, high incidence of disease,
premature aging, etc.
Cloning Genes
• Sometimes we clone genes and not more complex organisms
• Can you think of and example?
• ANIMATION
GMO”S
• http://geneticroulettemovie.com/
Transgenic Animals
• Goats can be made to secrete pharmaceutical products
• Goats can secrete human polypeptide in their milk
• Research trying to make animals viable organ donors for humans
• So far, limited success due to immune response in humans
Assessing the risks
• Transgenic products must be reviewed by government agencies for
approval.
• Social, economic, and environmental cost and benefit
• Biological characteristics of transgenic vs natural plant
• Potential health effects, including that the product may contain toxins
or allergens
Risks Cited
• Environmental: Herbicide resistant crops  more herbicide used
contaminated water as well as “superweeds” and “superbugs”
• Health: not enough understood about genetically modified foods
• Social/economic: help provide food for the poor or wastes money on
research?
Diagnosis and Treatment of Genetic Disorders
• Prenatal Diagnosis and Genetic Screening
• Ultrasound: sound waves sent through amniotic fluid bounce off the
developing fetus and create a cross-sectional image
• Can reveal physical abnormalities
• Amniocentesis: genetic makeup is found by sample tissue from the
amniotic fluid in uterus
• Cells multiply and researchers prepare karyotype
• Can only be done after the 14th week
• Chorionic villi sampling
• 9th week of pregnancy
• Sample taken from chorion (which are fetal cells)
• Can get a karyotype
Genetic markers
• A characteristic that provides information about the genotype of an
individual
• Can be a sequence of nucleotides that is known to associate with, or
be part of the gene of interest
• Can be found using a DNA probe
DNA Probe
• DNA molecule with a nucleotide sequence
complimentary to marker sequence “marked” with a
chemical tag
• DNA from sample is placed in suspension with probe
• If DNA sample contains gene of interest, probe will
bind to the marker sequence
• Tag will verify presence or absence of gene
Treating Human Genetic Disorders
• Gene therapy:
• the process of changing the function of a gene in order to treat or
prevent a genetic disorder
• Some disorders (diabetes, Parkinson’s) can be combated by targeting
their genetic causes, rather than simply treating symptoms.
DNA Vector
• Carries foreign DNA into target cells in the patient.
• Often a modified form of virus
• Viruses can target specific cells and insert their DNA into the genomes
of these cells
• Viruses can be genetically altered to carry a desired gene using
restriction endonucleases
Risks with viral vectors
• Viral protein coat can trigger an immune response, including high
fever and organ failure
• Some researchers fear virus may regain some pathogenic properties if
it comes into contact with other viruses
• Due to risks, researchers are looking into artificial chromosomes as
vectors
What is Gene Therapy?
• Link
Ethics Gene Therapy
• So far, mainly somatic gene therapy aimed at correcting genetic
disorders in somatic cells
• Which may improve the health of a patient, but does not prevent
disorder from being passed on to next generation
Germ-line Therapy
• More controversial, can modify information carried in egg or sperm
cell.
• Theoretically, could eliminate inherited genetic disorders
• Realistically, could have unforeseen effects on future generations
• Currently-banned in Canada
Questions raised
• What genetic conditions are “disorders” that deserve treatment?
• How much control should parents have to “design” there child?
• Potential benefits must be balanced with public interest and beliefs.
Virtual labs
• Go to http://learn.genetics.utah.edu/
• Search and do the following labs
•
•
•
•
Gel Electrophoresis
Click and Clone
Space Doctor (at least one patient and 2 vectors)
PCR Virtual Lab