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Genetic
Engineering
MILLER-LEVINE BIOLOGY BOOK
PAGES 247-259
BREEDING
TECHNIQUES
Selective Breeding:
Description:

The oldest and most obvious way
of improving species

Select a few individuals to serve
as parents for the next generation

Cross individuals with a desired
trait
Example(s): Luther Burbank produced 250 new
varieties of fruit in addition to the daisy and
Burbank Potato
Inbreeding:
Description:
• Technique used to maintain a stock of similar
organisms
 Individuals with similar characteristics are
crossed so the traits will appear again in next
generation
PROBLEM: Increased risk of recessive genetic
defects.
Example(s): Purebred dogs
Hybridization:
Description:
 A cross between dissimilar individuals of
different, but related species
 Offspring are often hardier than either
parent
Example(s): Commercially grown corn
Mutagens:
Description:
A breeder might not want to wait for a
beneficial mutation to appear naturally. They
catalyze this!
Mutagens include radiation and chemicals.
They cause mutations
• With luck and time, breeders end up with
“good” mutants
Example(s): Useful bacterial strains. Some
bacteria can digest oil are are useful in cleaning
up oil spills.
GENETIC
ENGINEERING
ARTIFICIALLY ALTERING GENETIC MAKE-UP, OFTEN
USING DNA FROM ONE ORGANISM IN ANOTHER
STEP 1: ISOLATE THE DESIRED GENE
Restriction Enzymes:
Proteins that cut DNA sequences at specific
regions
• More than 75 are known
• Each one recognizes a specific site of 4-6
nucleotide pairs and cuts
• Make it possible to cut DNA into fragment
that can be isolated, separated and analyzed
STEP 2: COMBINE THE GENE(S) WITH DNA FROM
RECIPIENT ORGANISM
DNA Recombination:
Insert desired gene into organism--often
bacterial plasmid (small circular pieces of
bacterial DNA)
• DNA now consists of parts from different
kinds of organisms
• This is “recombinant DNA”
STEP 3: INSERT COMBINED DNA INTO NEW
ORGANISM
DNA Insertion:
It is easiest to transfer DNA into bacterial
cells
• Mix plasmids in with millions of bacteria in a
salt solution
• Altered plasmids will carry foreign DNA into
bacterial cells
• Bacteria are isolated and grown into large
colonies to magnify the amount of the gene
(DNA cloning)
• Using different techniques, recombinant
DNA can be inserted into yeast cells, animals
and plants
GENETIC
SCREENING
DETERMINING THE NUCLEOTIDES ON DNA, USING
GEL ELECROPHORESIS
READ NEW SEQUENCES OF DNA
DNA Sequencing:
• Only one strand is used in DNA
sequencing
• Many copies of the strand are needed
and produced via DNA cloning
• Add radioactive phosphorus to DNA
• Divide DNA into 4 groups that undergo
different chemical treatments that break
DNA into pieces
• DNA pieces are separated by gel
electrophoresis and banding patterns are
analyzed to reveal sequence of bases
TRANSGENIC
ORGANISMS
ORGANISMS THAT
CONTAIN FOREIGN
GENES
BACTERIA:
Description:
• Organisms that contain foreign genes are transgenic
• When a gene coding for a human protein is inserted into
bacteria, the recombinant cells may produce large amounts of
the protein
Example(s): Human growth hormone, Insulin to
treat diabetes, Interferon to block growth of
viruses and treat cancer
PLANTS:
Description:
• DNA can be injected into plant cells directly
or attached to plasmids of certain species of
bacteria that infect plant cells
Example(s):
• The goal is to produce plants
that manufacture natural
insecticides and fertilizer
• Firefly gene inserted into
tobacco plant and it glowed!
ANIMALS:
Description:
• DNA can be introduced into reproductive
cells by injection, among other techniques
Example(s):
• Scientists introduced growth hormone gene from
rainbow trout into carp. The new fish were bigger and
faster growing.
• Another goal is to produce farm animals that are
resistant to disease.
CLONING
The production of genetically identical organisms
from single cells
CLONED ANIMALS:
Description:
• The nucleus of an egg cell
is removed and replaced with
a nucleus taken from an
adult organism
• The egg is grown inside a
foster mother
• The newborn is a genetic
copy of the adult from which
the nucleus was taken
Example(s):
• In 1997 “Dolly” the sheep was cloned.
Cows and mice have been cloned as well.
GENE THERAPY:
Transgenic Humans
Genetic Engineering to treat disease
GENETIC ENGINEERING IN HUMANS:
Description:
• Transgenic humans can be
produced by inserting foreign
genes into human cells
• Remove cells from an
individual and grow them in
culture. Transform with a
corrective gene and reinsert
• Viruses can be modified so
thatcause
you have
some scientific background you can
theyNow
cannot
disease
make and support your arguments.
Are you FOR or AGAINST GENETIC ENGINEERING?
Example(s):
• Cystic fibrosis, Tay-Sachs disease and sickle-cell anemia are examples of
genetic disorders that could be treated in this manner
Legislative Analyst - presents the necessary scientific
background required to understand the genetic engineering
application and the proposition – the law that is being proposed.
Paper and presentation should include:
Description of proposition
Explanation of SCIENCE background relevant to proposition
Proponent - presents the argument in favor of the proposition
and the science supporting the proposition.
Paper and presentation should include:
Position (YES on proposition)
Explanation of SCIENCE in support of proposition
Relevant ethical issues related to proposition
Opponent - presents the rebuttal to the argument in favor of the
proposition and the science against the proposition.
Paper and presentation should include:
Position (NO on proposition)
Explanation of SCIENCE against of proposition
Relevant ethical issues related to proposition