Download Ch. 13 – Biotechnology

Ch. 13 – Biotechnology
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Salt-tolerant Tomato Plants
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Transgenic β-carotene Rich Rice
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3 Key Tools
§  Restriction enzymes
-  cut DNA into fragments
§  Gel electrophoresis
-  analysis and purification of
DNA fragments
§  DNA ligase
-  joins DNA fragments
together in new
combinations
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Restriction Enzymes
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Restriction Enzymes
§  restriction endonucleases
§  discovered in 1960s
§  evolved in bacteria to cut up
foreign DNA
§  “restrict” action of attacking
organisms (viruses and other
bacteria)
§  How do bacteria protect their
own DNA?
§  Methylation
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Restriction Enzymes
§  cut at specific recognition sequences
§  “sticky ends”
§  Sticky ends can bind complementary sequences on
other DNA molecules.
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Gel Electrophoresis
§  separates DNA fragments cut
Animated Tutorial 13.1 –
Gel Electrophoresis
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by enzymes
§  provides information on:
-  number of fragments
-  sizes of fragments
-  relative abundance of
fragments (intensity of
band)
§  A specific DNA sequence can
be found with a singlestranded probe.
§  DNA fragment is removed and
used to make recombinant
DNA.
Check Your Understanding
1999
Exam
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How to Get Recomb DNA into Cells?
§  chemicals
-  make membrane more
§ 
§ 
§ 
§ 
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permeable
Electroporation
-  electric shock creates
temporary pores in membranes
Viruses and bacteria
-  carry recombinant DNA into
cells
Transgenic animals
Gene guns
-  shoot the host cells with
particles of DNA
Bacteria
Bacterial Fission
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Bacterial
Genome
-  single circular
chromosome
-  haploid
-  “naked” DNA
-  ~ 4 million base
pairs
-  ~ 4300 genes
-  1/1000 DNA in
eukaryote
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Transformation
§  Bacteria pick up naked foreign DNA
§  import bits of chromosomes from other bacteria and
incorporate into their own à express new genes
(transformed)
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Plasmids
-  small supplemental circles of
DNA (5000-20,000 bp)
-  2-30 genes
-  self-replicating
-  many have genes for antibiotic
resistance (selectable
markers)
-  can be exchanged between
bacteria (bacterial sex)
-  rapid evolution
-  can be imported from
environment
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Plasmids
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Sticky ends help glue genes together
cut sites
gene you want
cut sites
TTGTAACGAATTCTACGAATGGTTACATCGCCGAATTCACGCTT
!
AACATTGCTTAAGATGCTTACCAATGTAGCGGCTTAAGTGCGAA
!
sticky ends
AATTCTACGAATGGTTACATCGCCG
!
GATGCTTACCAATGTAGCGGCTTAA
!
cut sites
isolated gene
chromosome want to add gene to
AATGGTTACTTGTAACG AATTCTACGATCGCCGATTCAACGCTT
!
TTACCAATGAACATTGCTTAA GATGCTAGCGGCTAAGTTGCGAA
!
DNA ligase joins the strands
sticky ends stick together
Recombinant DNA molecule
chromosome with new gene added
TAACGAATTCTACGAATGGTTACATCGCCGAATTCTACGATC
CATTGCTTAAGATGCTTACCAATGTAGCGGCTTAAGATGCTAGC
!
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The Code Is Universal
§  Since all living
organisms…
-  use the same DNA,
same code book
-  read their genes the
same way
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Copy (& Read) DNA
§  Transformation
-  insert recombinant plasmid
into bacteria
-  grow recombinant bacteria in
agar cultures
-  bacteria make lots of copies of
plasmid – “cloning” the plasmid
-  production of many copies of
inserted gene
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pGLO Bacterial Transformation
§  Selectable markers
-  antibiotic (ampicillin) resistance
§  Reporter gene
-  jelly fish
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Check Your Understanding
2012
Practice
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Uses of Genetic Engineering
§  Genetically modified organisms
(GMO)
-  enable plants to produce new
proteins
-  protect crops from insects
(BT corn)
-  extend growing season:
“fishberries”
-  golden rice containing βcarotene
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