Download REVIEW SHEET FOR GENETIC ENGINEERING AND TRANSGENICS

REVIEW SHEET FOR GENETIC ENGINEERING AND TRANSGENICS
TERMS:
Recognition (restriction) sites: a 4 or 8 base pair sequence that is a palindrome. It’s where restriction enzymes
recognize and cut at specific places along the DNA molecule.
Restriction maps: A restriction map shows the location of cleavage sites for many different enzymes, so scientists can
figure out where restriction sites are. They are maps to the DNA molecule
Sticky Ends: A DNA fragment that has ends exposed to nucleotides at each end- When restriction enzymes cut a DNA
molecule, the single-stranded tails are the sticky ends- They’re easy to rejoin to complementary sticky ends
Blunt Ends: A DNA fragment whose ends are not exposed to any nucleotides on each end- When restriction enzymes
cut the 2 DNA strands directly across from one another, a blunt end is formed
DNA probes: A section of single-stranded, radioactive DNA that is used to detect and label a complementary sequence
of DNA- used after gel electrophoresis to help make an autorad)- radioactive- attach themselves to DNA fragments
Bands: Each is composed of 1000’s of DNA fragments. Bands that have traveled equal distances consist of fragments
that are the same length, but not necessarily the same sequence- The DNA strips seen after gel electrophoresis
DNA fingerprinting: Technique that compares the pattern of DNA bands from a suspect, produced during gel
electrophoresis, with the pattern of bands from the DNA evidence- Every DNA sample has its own unique apttern- can
be used for identification
Barr Body:
Genetic Marker: A gene that makes it possible to distinguish between an organism that carries a foreign DNA and one
that doesn’t- The marker codes for an easily observable trait. It could show if transformation was successful
Cloning: Technique that produces an individual that is genetically identical to another organism (in many animals, it
involves inserting DNA from a body cell into an egg cell)
Transformation: Process of inserting recombinant DNA into a living cell (usually involves a vector)
Plasmid: A small, circular piece of DNA found in bacteria (separate from the chromosome)- small circular pieces of
DNA within bacteria
Vector: An agent that introduces foreign DNA into a host cell- Ex. Virus, plasmid in gene therapy, a vector delivers the
desired gene to the target cell- carrier of genetic material
Short tandem repeats (or VNTR): They consist of simple, repetitive sequences of DNA found mainly in the intergenic
regions of a chromosome. They tend to differ from person to person are often used to produce the “DNA fingerprint”
Autorads: A photo that shows the location and pattern of the radioactive probes hybridized to the electrophoressed
DNA fragments
Gene Therapy: The practice of inserting functional genes to do the work for nonfunctional genes
Transgenic Organisms: An organism that has been genetically engineered to contain DNA from different species
Golden Rice: Beta-carotene produces Vitamin A- 250 million people suffer from Vitamin A deficiency- 1/2 million go
blind each year- 1/2 the world’s population depends on rice- Scientists inserted the beta-carotene gene into rice, giving
it the golden color of daffodils- this is recombinant DNA, a form of genetic engineering
Bt Corn: Bacillus Thuringiensis- lives in soil- the genes in BT bacterium are important so they can be inserted in other
cells- it’s safer than pesticides because it’s natural- caterpillars, first stage of life for Monarch butterflies, are affected
and killed by it- Superbugs that are resistant to Bt Corn will evolve and eventually not be affected by this natural
pesticide
PCR process and primers: Technique that uses DNA polymerase to make copies of a specific section of DNA (millions
of copies of DNA can be copied in a matter of hours). Primer is a short DNA or RNA fragment that anneals to single
stranded DNA. It allows DNA polymerase to start replication the DNA molecule- invented my Dr. Kary Mullis
Southern Blotting: A procedure in which DNA is transferred from a gel to a membrane filter and hybridized with a
radioactive DNA probe- X-ray film can be placed over the membrane to produce an autorad that mirrors the locations
of the targeted DNA bands on the gel
Gel electrophoresis procedure and applications (including lab): A process in which molecules are sorted by size as they
are pulled by an electrical current through a gel- used to see if restriction enzymes worked- Phosphate groups of DNA
are negatively charged and attracted to the positive charge of the electricity- Comb is inserted to make sample wells for
DNA- agarose gel is a thick, porous, Jello-like substance- nylon membrane secures the DNA fragments in the fragile
gel
Restriction enzymes uses and naming: Restriction enzymes are the “molecular scalpels” that allow genetic engineers to
cut up DNA molecules in a controlled way- they’re proteins that prevent, or restrict, invasion by foreign DNA- break
DNA bonds at precise locations- 3 parts of their names: 1. From the bacteria it was discovered from; 2. Which strand it
comes from; 3. Number of enzyme found (Ex. EcoR1)
Making of recombinant DNA: DNA that contains fragments derived from 2 or more different sources- Using sticky or
blunt ends, the complementary nitrogenous bases match and to another DNA strand creating a DNA strand from 2 or
more sources
Transforming bacteria, plant cells, and animal cells with use of vectors (viral, plasmids, gene gun):
Plasmid Vectors: Plasmids are naturally occurring accessory chromosomes found in bacteria. Plasmids are
usually transferred between closely related microbes by cell-to-cell contact. Simple chemical treatments can make
mammalian cells, yeast cells and some bacterial cells that do not naturally transfer DNA, able to take up external DNA
Viral Vectors: Viruses are well suited for gene therapy. They can accommodate up to 7500 bases of inserted
DNA in their protein capsule. When viruses infect and reproduce inside the target cells, they are also spreading the
recombinant DNA. They have already been used in several clinical trials of gene therapy for different diseases. A
problem wit this method involves the host immune reaction to the virus.
Pronuclear and Ballistic DNA Injection: DNA can be introduced directly into an animal cell by microinjection.
Multiple copies of the desired transgene are injected via a glass micropipette into a recently fertilized egg cell, which is
then transferred to the surrogate mother. The process is inefficient because only 2-3% of eggs give rise to transgenic
animals and only a proportion of these animals express the added gene adequately- Microscopic particles of gold or
tungsten are coated with DNA. They are propelled by a burst of helium into the skin and organs of animals, and tissues
of intact plants. Some of the cells express the introduced DNA as if it were their own.
Advantages and Disadvantages of transgenic Plants (Genetically Modified Foods issue):
Advantages: first applications increased cop yields by designing plants that were resistant to pests and therefore
reduced the use and expense of harmful pesticides- engineer plants that are capable of degrading weedkillers
(Roundup) so that crops are not harmed when spraying for weeds- improve nutrional value of crops (Golden Rice with
beta-carotene)- extend the shelf life of produce (tomatoes, bananas)- Bioremediation-engineer plants that are capable of
removing large quantities of toxic substances from the soil- in the future, design crops that contain edible vaccines
Disadvantages: plants engineered to produce natural pesticides present 2 potential problems: 1. some species of
insects could evolve a resistance to the pesticide and actually make it more difficult to control pest problems
(evolution); 2. Presence of pesticides could harm beneficial, non target species- Superweeds-transgenic plants can
hybridize 9cross pollinate) with closely related wild plants. If these wild plants were to acquire the genes that made
them resistant to weedkillers, they might crowd out other important species of plants and disrupt the ecosystemgenetically modified foods could trigger an allergic reaction in unsuspecting individuals if they carried genes for an
allergen from a different food. Detractors call them “Frankenfoods” and worry that they will pollute the food supply
with new and toxic chemicals- cloning of plants and animals reduces the genetic diversity of population. Genetic
variation is the goal of sexual reproduction. Variation is good in changing environments and reduces catastrophic losses
from disease susceptibility- Not what God made- Prices