Regents Biology 2006-2007

Genetic EngineeringBiotechnology

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We have been manipulating DNA for generations! Artificial selection – selective breeding

Humans choose parents with desired traits creating new breeds of animals & new crop

plants to improve our food

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Animal breeding

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Breeding food plants “Descendants” of the wild mustard

the “Cabbage family”

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Breeding food plants

Evolution of modern corn (right) from ancestral teosinte (left).

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A Brave New World

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The code is universal Since all living

organisms… use the same DNA use the same code

book read their genes

the same way REDUNDANCY IN

THE CODE – more than one codon for some amino acids

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Can we mix genes from one creature to another?

YES!

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Mixing genes for medicine… Allowing organisms to produce new proteins

– TRANSGENIC ORGANISMS bacteria producing human insulin bacteria producing human growth hormone

THIS IN NO WAY BENEFITS THE BACTERIA

So why do this? - Fairly easy, cheaper, and less side effects

Genetically Modified

Organisms (GMOs)

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Uses of genetic engineering Genetically modified organisms (GMO)

enabling plants to produce new proteins Protect crops from insects: BT corn

corn produces a bacterial toxin that kills corn borer (caterpillar pest of corn)

Extend growing season: fishberries strawberries with an anti-freezing gene from flounder

Improve quality of food: golden rice rice producing vitamin A improves nutritional value

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How do we do mix genes? Genetic engineering

find gene – human genome cut DNA in both organisms – need enz + ATP paste (splice) gene from one creature into other

creature’s DNA producing recombinant DNA insert new chromosome into organism (transgenic) organism copies new gene as if it were its own –

replication for m______ & m_________ (One cell can pass info on to many others)

organism reads gene as if it were its own organism produces NEW protein (has that trait):

Remember: we all use the same genetic code!

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TACGCACATTTACGTACGCGGATGCCGCGACTATGATCACATAGACATGCTGTCAGCTCTAGTAGACTAGCTGACTCGACTAGCATGATCGATCAGCTACATGCTAGCACACYCGTACATCGATCCTGACATCGACCTGCTCGTACATGCTACTAGCTACTGACTCATGATCCAGATCACTGAAACCCTAGATCGGGTACCTATTACAGTACGATCATCCGATCAGATCATGCTAGTACATCGATCGATACTGCTACTGATCTAGCTCAATCAAACTCTTTTTGCATCATGATACTAGACTAGCTGACTGATCATGACTCTGATCCCGTAGATCGGGTACCTATTACAGTACGATCATCCGATCAGATCATGCTAGTACATCGATCGATACTGCTACTGATCTAGCTCAATCAAACTCTTTTTGCATCATGATACTAGACTAGCTGACTGATCATGACTCTGATCCCGTAGATCGGGTACCTATTACAGTACGATCATCCGATCAGATCATGCTAGTACATCGATCGATACT

human genome3.2 billion bases

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DNA “scissors” enzymes that cut DNA restriction enzymes

used by bacteria to cut up DNA of attacking viruses (found naturally)

Examples : EcoRI, HindIII, BamHI

cut DNA at specific sites – usually palindromes enzymes look for specific base sequences

Cutting DNA

GTAACG|AATTCACGCTTCATTGCTTAA|GTGCGAA

Cleavage sites

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Restriction enzymes Cut DNA at specific sites - palindromes

leave “sticky ends” – allows for base pairing

GTAACG AATTCACGCTTCATTGCTTAA GTGCGAA

GTAACGAATTCACGCTTCATTGCTTAAGTGCGAA

restriction enzyme cut site

restriction enzyme cut site

“sticky ends” – AATT and TTAA

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Sticky ends Cut other DNA with same restriction enzymes

Leaves same “sticky ends” on both can glue (splice) DNA together at “sticky ends” –

complementary bases will pair up and H-bonds form

GTAACG AATTCACGCTTCATTGCTTAA GTGCGAA

gene you want

GGACCTG AATTCCGGATACCTGGACTTAA GGCCTAT

chromosome want to add

gene to

GGACCTG AATTCACGCTTCCTGGACTTAA GTGCGAA

combinedDNA

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TAACGAATTCTACGAATGGTTACATCGCCGAATTCTACGATC CATTGCTTAAGATGCTTACCAATGTAGCGGCTTAAGATGCTAGC

Why mix genes together? Gene produces protein in different

organism or different individual

aa aaaa aa aa aa aa aa aa aa

“new” protein from organism ex: human insulin from bacteria

human insulin gene in bacteria

bacteria human insulin

How can bacteria read human DNA?

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Bacteria Bacteria are great!

one-celled organisms reproduce by mitosis

Natural cloning makes copies of gene easy to grow, fast to grow

generation every ~20 minutes

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Single circular chromosome only one copy = haploid no nucleus

Other DNA = plasmids!

Bacterial DNA

bacteriachromosome

plasmids

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There’s more… Plasmids

small extra circles of DNA carry extra genes that bacteria can use can be swapped between bacteria

bacterial sex!! rapid evolution = antibiotic resistance

can be picked up from environment

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How can plasmids help us? A way to get genes into bacteria easily

insert (splice) new gene into plasmid insert plasmid into bacteria = vector bacteria now expresses new gene by

making the new protein

+

transgenicbacteriagene from

other organism

plasmid

cut DNA

recombinantplasmid/DNA

vector

glue DNA - (splice)H-bonds form

between “sticky ends”

MUST USE SAME

RESTRICTION ENZYME

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Grow bacteria…make more

Bacteria reproduceBy MITOSIS

And Copy DNA

harvest (purify) protein for use - Leave some bacteria to continue

to reproduce and make more protein

transgenicbacteria

plasmid

gene fromother organism

+

recombinantplasmid

vector

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Applications of biotechnology1. human insulin2. human growth hormone3. gene for pest resistance in plants4. gene used to alter bacteria to clean up

toxic waste5. protein to dissolve blood clots in heart

attack therapy