Notes: Biotechnology - Hart High School

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Notes: Biotechnology


Important Vocabulary


Genetic Engineering: use of DNA Technology to alter genes for useful purposes


DNA Technology: any technique that changes DNA


Transformation: process where a cell takes up external DNA, incorporates it into its

own genome, and begins
expressing the new DNA’s encoded proteins


Recombinant DNA: DNA that contains information from two different sources


Transformation


Fred Griffith in 1928 was the first to explore transformation


While testing two strains of bacteria

on mice, he found that it is possible to infect mice with pneumonia even
though the bacteria he injected them with was supposed to be harmless!!!


Transformation Experiment


View Griffith’s experiment online at
http://www.uic.edu/classes/bios/bios100/summer2003/freddy.htm


Isolating and Storing a Gene


Thanks to Griffith and those that followed him, we know that


DNA controls inheritance


Organisms can take up and use DNA that was not

theirs to begin with


In order to complete their own transformation experiments now, scientists have developed means of
identifying and storing genes



Step 1: Choose and sequence a “gene of interest”


To sequence a gene, scientists take a single strand of
DNA and…


Add it to a test tube with DNA Polymerase and free A, C, T, & G bases


Treat the bases with a colored chemical dye


Allow replication to finish


Using gel electrophoresis, different colored bases will be visible in the new strand of DNA and the seque
nce of
bases can be read from the colors


FYI: The Human Genome Project


The Human Genome Project


This project was completed in April of 2003. Scientists have sequenced the entire human genome


They have isolated all of the base pairs in the many genes th
at make up a human



The info is being used to understand gene expression, evolution, cell differentiation, and organization
of genomes


Isolating and Storing a Gene


Step 2: Cut out the “gene of interest” using a restriction enzyme


Restriction Enzyme: an
enzyme that naturally occurs in bacteria; identifies particular DNA sequences
and cuts at those sequences

(these enzymes are also called endonucleases)


Restriction enzymes leave “s
ticky ends.”


Restriction Enzymes


Action of enzyme


cut DNA at specific seq
uences


restriction site


symmetrical “palindrome”


produces protruding ends


sticky ends


Many different enzymes


named after organism they are found in


EcoR1, HindIII, BamH1, Sma1


Isolating and Storing a Gene


Step 3: Choose a “cloning vector” and cut it with

an appropriate restriction enzyme


A “cloning vector” is a plasmid (circular piece of DNA) with known restriction sites that the “gene of
interest” can be inserted into for copying and transforming bacteria


FYI: Cloning Vectors


A cloning vector is a plas
mid


Plasmid


circle of DNA commonly found in bacteria


Plasmids are useful for 2 reasons:


They have DNA sequences that ensure that DNA Replication will happen in the plasmid and ultimately
the gene planted in the plasmid.


They have a genetic marker (usuall
y antibiotic resistance) that makes it possible to see which bacteria
have been transformed by the plasmid and which ones have not.


Isolating and Storing a Gene


Step 4: Mix “cloning vector” and “gene of interest” together


Sticky ends in cloning vector an
d gene of interest should be complementary so that the gene sticks in
the plasmid


The gene will “glue” into the plasmid because of the enzyme DNA Ligase


Gene can be stored in a vector or implanted into a host organism for growth and use


Working with DNA


T
hink about it

DNA is awfully small. How can you be sure you have enough DNA for your experiments and
how can you be sure a gene has ended up where you wanted it?


The next few slides examine how scientists amplify DNA and check for its presence.


Copying D
NA


Polymerase Chain Reaction (PCR) is a technique used to quickly replicate large quantities of DNA


DNA is small, and to effectively experiment with it, large quantities are needed


PCR uses the enzyme
taq

polymerase (a type of DNA Polymerase) at high tempe
ratures to simulate an
environment needed for replication


Testing for a Gene


Gel Electrophoresis is used to separate DNA fragments by applying an electrical charge to the fragments.


DNA must first be cut with a restriction enzyme


When an electrical curren
t is applied the, negative ends of the DNA fragments are pulled down a gel


The large fragments of DNA stay at the top of the gel, the smaller pieces travel to the bottom


A gel is useful to see if a gene has been inserted into its correct cloning vector


If
you do this right, a restriction enzyme will cut out your gene and you can prove the gene is there
based on its size.


Gel electrophoresis is also used to create DNA Fingerprints for paternity testing or suspect identification in
criminal investigations.


Ag
ain, by comparing different fragment lengths of DNA, you can compare a piece of a child’s DNA with
its parents’ or a criminal’s with a bunch of suspects


This is called RFLP (restriction fragment length polymorphism) Analysis


Testing for a gene may also be
done using a genetic marker in a plasmid


The most common approach is to transform bacteria with an antibiotic resistant plasmid and then allow the
bacteria to grow on a plate that is positive for the antibiotic.


Only the bacteria that have taken up the pla
smid will survive on the plate.


Those are the bacteria who positively have the gene of interest.


A Practical Use For This Stuff…


The following demo shows how insect resistant plants are made.


An insect resistant plant is one that kills (poisons) certain i
nsects that try to feed upon it…


http://www.pbs.org/wgbh/harvest/engineer/transgen.html



Biotechnology Uses


The next group of slides explain and illustrate how genetic engineering is us
ed for:


Agriculture


Medicine


Animal and Plant Breeding


Forensic Science


Agricultural Uses of Biotech


Agriculture has apparently benefitted from genetic engineering


Plants have been implanted with DNA make them insect or weed resistant


Video

insect resista
nt plant (bt corn)
http://www.dnatube.com/view_video2.php?viewkey=f50967c64dac2d639a57


Tomatoes have been genetically altered so that they ripen without becoming soft


Animal
s are cloned to perpetuate the strong characteristics of a farmer’s best animals (
article
)


People have concerns that genetically altered food may affect allergies for people who eat it or c
ause
ecological damage


Medical Uses of Biotech


Disease Prevention


Vaccines

solutions of “dead” pathogen that when inserted into a body allow the body to produce
antibodies against the pathogen


Gene Therapy


Insertion of healthy DNA into a body of one who h
as a genetic disease


Does not cure the disease but may lessen or relieve its symptoms


Cystic fibrosis is treated with a therapeutic nasal spray


Pharmaceuticals


Many proteins can be grown for human use by inserting the genes for those proteins into bacteria

and
then harvesting the products


Examples include


Insulin for diabetes


Human Growth Hormone for dwarfism


Clotting factors to aid in wound healing, including treatments for hemophiliacs


Selective Breeding & Biotechnology


Selective Breeding is used by s
cientists & breeders trying to perpetuate particular traits in an organism


Hybridization


crossing dissimilar organisms in order to bring together the best of their traits


Desirable traits are chosen and breeding situations are “optimized” to ensure those

traits are passed on


For optimal passing of desired traits, breeders rely on inbreeding and controlled pollination


Purebred pets and many specialty plants have been designed and maintained via selective breeding


To introduce more desirable traits in organ
isms, breeders may try to induce mutation in an organism.


New types of bacteria that aid in bioremediation have been created this way


Bioremediation


use of microorganisms to breakdown environmental contaminants and return an
ecosystem to its normal state


New plant types have been created by treating them with drugs to induce polyploidy (too many chromosomes)
which in turn produces unique colorations petal patterns for flowers


Biotechnology & Cloning


There are 3 types of cloning


Recombinant DNA Technology

(DNA Cloning)

insertion of a gene into a host or cloning vector and
using PCR or a host to copy the gene


Reproductive Cloning

creation of an individual whose nuclear DNA is the same as another individual


Therapeutic Cloning

production of human embryos for

the purpose of harvesting stem cells


Biotechnology & Forensic Science


Collecting and analyzing DNA from a crime scene is part of forensic science


DNA collected can be cut and analyzed via gel electrophoresis to identify and incriminate suspects


A DNA Fin
gerprint is a method of identifying an individual by analyzing their DNA


Issues in Biotechnology


The following slides define and give a chance to interact with some of the more current issues/concerns in
biotechnology:


GMO Foods


Cloning


The Human Genome P
roject


Personal Genome Libraries


Forensic Science


GMO Foods


GMO Food


A genetically modified food produced using a Genetically Modified Organism


Controversy surrounds them…Will they…


Cause defects in those of us who eat them?


Affect allergic reactions in

those of us who eat them?


Cause environmental damage?


Some Cloned Creatures
…sheep, cat…and all the rest


The Personal Genome Project


Genome Libraries


The January 2006 issue of
Scientific American

reported on the Personal Genome Project


The idea is to tak
e volunteers to donate their DNA for sequencing and gene identification


Their gene info and medical records would become public so that all could benefit from studying and
understanding an individual’s personal genetic information


http://www.personalgenomes.org/