Transcript Genetic Engineering: How and why scientists

Genetic Engineering:
How and why scientists
manipulate DNA in living
cells
http://farm3.static.flickr.com
Karyotype
chart of chromosome
pairs used to identify
unusual #s of chromosomes
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**Down syndrome (Trisomy 21) – 3 chrom. at pair 21
Turner’s syndrome – only one X – sterile female XO
Klinefelter’s syndrome – extra X (male:XXY-sterile)
Karyotype
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/D/Down.gif
http://www.biologyreference.com/images/biol_04_img0412.jpg
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Nondisjunction – causes these unusual #s of
chromosomes; chromosomes fail to separate
during meiosis
http://www.medgen.ubc.ca/wrobinson/backup/mosaic/images/nondis_m2.gif
http://www.ratsteachgenetics.com/Genetics_quizzes/Lecture%207/7q1.jpg
Selective breeding
We choose desired
traits & breed plants and
animals to have these traits
*Takes decades
 Examples: popcorn,
dog breeds, cows produce
3x more milk than 50 years ago, bigger peaches,
apple varieties
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http://img.dailymail.co.uk/i/pix/2008/02_02/CaulliDM_468x518.jpg
Selective breeding – 2 methods
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1. Hybridization – cross dissimilar individuals
to bring together best traits
Ex. Crossing disease-resistant apple with high
yield apple = apple tree that
produces a lot and requires
less pesticides
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http://www.biologyreference.com/images/biol_02_img0235.jpg
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2. Inbreeding – done to maintain traits
*because genetics are so close, often allows
expression of recessive allele
 Study revealed that
20,000 boxers genetically
look like 70
-deaf dalmations &
white boxers, heart disease,
hip dysplasia
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http://www.boxerbuddies.org/Boxer%20Info/oscar10.jpg
Test cross
A way of determining genotype
 Cross a known individual (homozygous recessive) with an unknown –
homozygous dominant or heterozygous
If unknown is homozygous dominant, all offspring will
show dominant trait
If unknown is heterozygous, some will show dominant
trait, some show recessive trait
Complete Problem Solving Lab 13.1 p.339
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http://farm3.static.flickr.com/2023/2503367977_4a5dc2345a.jpg?v=0
Manipulating DNA
Process
How
Cut DNA
Restriction Enzymes
(like scissors)
Sort DNA
Gel Electrophoresis
Analyze DNA
DNA fingerprint
1. Cut DNA: Restriction enzymes
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DNA is too large to be analyzed
Highly specific restriction enzymes from bacteria cut
DNA into precise pieces between certain base pairs
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Ex. EcoRI can only recognize GAATTC – it cuts between
the G and A
Leaves “sticky ends” – single-stranded overhangs
used to bond “stick” to another DNA stand cut with
the same restriction enzyme
Practice p.343
Restriction enzymes
http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ge/m6/s1/assets/images/gem6s1_1.jpg
2. Sort DNA: Gel Electrophoresis
3. Result: DNA fingerprint
1.Insert restriction-enzyme-cut
DNA into gel
2. Add electricity.
Shorter fragments move farther
p. 346
http://www.bio.miami.edu/~cmallery/150/gene/c7.20.8.electrophoresis.jpg
3. Analyze DNA: DNA fingerprinting
*Sample from
blood, hair, skin,
semen
*Use PCR
(polymerase
chain reaction)
to make more
http://dnamazing.com/wp-content/uploads/2007/08/dnabasics2.JPG
Can you match the evidence with the
suspect?
PS lab 13.3 p.353
http://images.encarta.msn.com/xrefmedia/sharemed/targets/images/pho/t235/T235690A.jpg
Human Genome Project (1990-2003)
*Sequenced all 3 billion base pairs of human
DNA and identified
all human genes.
*Used to determine
carriers for diseases
& develop gene
therapy
http://www.sanger.ac.uk/Info/Press/gfx/030414_hgp_300.jpg
Product of
Human Genome:
chromosome
maps
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http://www.mhhe.com/biosci/genbio/maderbiology7/graphics/mader07b/online_vrl/images/0287l.jpg
Genetic engineering:
faster than selective
breeding. Cut DNA
from one organism,
insert into another.
 Recombinant
DNA: combining
DNA from different
sources
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http://campus.queens.edu/faculty/jannr/Genetics/images/dnatech/bx15_01.jpg
Transgenic organisms
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Contain genes from other species
Insert recombinant DNA into a new host
Use plasmid – circle of DNA in bacteria
Insert recombinant DNA into plasmid, reinsert
plasmid into bacteria- bacteria clones DNA as it
divides (mitosis); get lots of copies of DNA
Used to produce insulin to treat diabetes, human
growth hormone, blood-clotting factors for
hemophiliacs, potentially even cancer-fighting
molecules (interleukin-2 and interferon)
Recombinant bacteria manufacture insulin
http://www.bio.miami.edu/~cmallery/150/gene/c7.20.4.insulin.jpg
http://www.e-ishraq.com/v4/images/6_3.gif
Cloning
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Uses a single somatic
cell from an adult
organism to grow an
entirely new
genetically identical
organism
http://static.howstuffworks.com/gif/cloning-sheep.gif
Uses of transgenic animals
Insert spider genes into cells of lactating goats –
manufacture silk along with milk = light, tough,
flexible material  military uniforms, medical
sutures
 30% of US milk produced
by genetically modified (GM)
cows
 Pigs GM to produce
high levels of lean meat
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http://www.scienceprogress.org/wp-content/uploads/2009/01/goat_591.jpg
Transgenic plants: Golden Rice – GM
to have high levels of beta-carotene –
essential for health, eye sight
http://upload.wikimedia.org/wikipedia/en/thumb/8/88/GoldenRice-WhiteRice.jpg/800px-GoldenRice-WhiteRice.jpg
http://www.bio.davidson.edu/courses/GENOMICS/2008/Waters/TIME.jpg
Gene therapy
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Absent or faulty genes replaced by normal
working genes – allows body to make
proteins or enzymes needed, eliminating
disorder
Used to treat SCID (severe combined
immunodeficiency syndrome)
Trials for sickle-cell, cystic fibrosis, and
hemophilia treatments are going on now
http://library.thinkquest.org/28000/media/genetherapy/l_gene.therapy-ms.gif
Future possibilities?
http://ec1.images-amazon.com/images/I/51EbEYn8hAL.jpg
Implications? Ethical issues?
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Patenting life
Genetic ownership
GINA (Genetic Information
Nondiscrimination Act) passed in 2008
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Protects Americans against discrimination from
employers or insurance companies based on
genetic information
http://media-2.web.britannica.com/eb-media/64/47664-004-7088EE3D.jpg