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1 Review Describe the process scientists use to copy
DNA
Use Analogies How is genetic engineering like
computer programming
2 Review What is a transgenic organism
Compare and Contrast Compare the transformation
of a plant cell with the transformation of an
animal cell
3 Practice Design an experiment to find a way to treat
disorders caused by a single gene. State your
hypothesis and list the steps you would follow
CH 15 GENETIC ENGINEERING
15.2 Recombinant DNA
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Suppose you have an electronic game you want to
change
Game depends on a coded program in a computer
microchip
Need to remove the program, change the code and
put the modified chip back
Same for genetic engineering.
Copy DNA
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Easy to extract DNA
Cut using restriction enzymes
Use gel electrophoresis.
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Douglas Prasher wanted to find a jellyfish gene
called green fluorescent protein (GFP)
Protein it makes absorbs energy from light and
makes parts of the jellyfish glow
Looked at amino acid sequence protein and
predicted mRNA
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Cut up jellyfish DNA with restriction enzymes
Added his mRNA prediction
DNA piece with actual gene on in bonded to the
mRNA
Southern Blot test
 Technique to
find specific DNA sequence by using a
segment of nucleic acid.
Polymerase Chain Reaction (PCR)
Technique to make
many copies of a DNA
segment or gene
1. A piece of DNA is
heated, which separates
its two strands.
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2. At each end a known
primer is added
 Allows
DNA polymerase
a place to begin.
3. DNA polymerase copies
the region between the
primers
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These copies then serve
as templates for more
copies
4. A few dozen cycles of
replication can produce
billions of copies of the
DNA.
Recombinant DNA
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DNA produced from combining DNA from different
organisms.
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Scientists can produce custom-built DNA
molecules and insert them into living cells
DNA synthesizers
 Make
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short pieces of DNA
Synthetic sequences can be joined to natural
sequences using DNA ligase
 Enzyme
that spices DNA together.
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Cut DNA using restriction enzyme
 Results
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in a chunk of DNA with a sticky end
Cut another DNA molecule with the same
restriction enzyme
Sticky ends from the two different molecules can
be joined with DNA ligase.
Plasmids
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Small circular DNA molecules in bacteria
Add DNA to plasmid and then the bacteria it is
located in will duplicate itself and the added DNA.
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Plasmids used for
genetic engineering
contain a start signal origin of replication
(ori), and a restriction
enzyme cutting site,
such as EcoRI.
Genetic Marker
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Gene that makes it possible to distinguish bacteria
that carry the plasmid from those that don’t.
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In addition to added
gene, add a genetic
marker such as
antibiotic resistance
genes tetr and ampr
Grow bacteria in a dish
treated with antibiotics
and those who survive
have the genes.
Transgenic Organisms
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Organism that has genes from another speices
Produced using recombinant DNA.
Transgenic Plants
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Many plant cells can be transformed using
Agrobacterium
 Normally
causes plant tumors
 Deactivate tumor producing gene and replace it with
the gene you want to add to the plant
 Bacteria infects plant cells
 Culture those plant cells into adult plants that have
the DNA you added.
Transgenic Animals
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Can use same techniques as plants
Some egg cells are large enough to inject DNA
directly into the nucleus
Also able to remove particular genes through a
similar process.
Clone
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Member of a population of genetically identical
cells produced from a single cell
Single cell from an adult organism used to grow an
entirely new individual that is genetically identical
to the organism from which the cell was taken
1952 tadpoles
1997 Dolly.
Nuclear Transplantation
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Nucleus of an unfertilized egg is removed
Egg cell is fused with a donor cell that contains a
nucleus from an adult you want cloned
Diploid egg develops into an embryo, which is
then implanted in the uterine wall of a foster
mother, where it develops until birth
Nuclear Transfer is similar.
Inserting Genetic Markers
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Write a random DNA sequence on a long strip of
paper to represent an organism’s genome
Have your partner write a short DNA sequence
on a short strip of paper to represent a marker
gene
Using the chart provided, work with your partner
to figure out how to insert the marker gene into
the genome
Inserting Genetic Markers
1.
2.
Apply Concepts Which restriction enzyme did
you use- why
Use Models What kind of molecule did you and
your partner develop