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Anu Singh-Cundy • Michael L. Cain
Discover Biology
FIFTH EDITION
CHAPTER 16
DNA Technology
© 2012 W. W. Norton & Company, Inc.
Genetic Code: 3 things to know
1. Unambiguous: if I show you a codon, there’s
no question which amino acid to use next
2. Redundant: most amino acids have more
than one codon
Genetic Code: Universal (3)
Use same genetic code:
Animal, Plant, Bacteria,
Fungi, Protist, Archea
A gene’s codons have the
same meaning even if you
put them in a different
organism
Why we can do this 
Artificial Selection: Have done for centuries
Old way to manipulate genes
• Breed animals/plants
• Select any favorable new traits (mutations)
• Breed THOSE animals/plants
Manipulating Genes: The Old way
People manipulating genes (Selective Breeding)
We breed the ones
we like, until they
are ALL what we
want
Other examples
http://www.businessinsider.com/how-fruits-have-evovled-over-time-2014-10
Belgian Blue Cattle: muscle growth mutation
Some cattle grow muscle at a faster rate
(mutation turns off genes
that regulate muscle growth)
Breed THOSE animals until all your cattle have lots of
muscle.
People selected for a naturally occurring
mutation and only bred the cattle with the
allele that increased muscle growth
The babies bulk up so fast
that they are delivered
by cesarean section
DNA techology/Biotechnology
A newer way to control genes in organisms
• Approx. 40 years (since 1970s)
• Turn a gene on
• Turn a gene off
• Add a new gene
Manipulating Genes: The new way
• Eduardo Kac: Human genes in petunia!!!
• Chickens without feathers!!
Nerd Words
Restriction Enzymes: How bacteria fight viruses
Cut DNA into small pieces
cut in specific sequences
some leave jagged (“sticky”) ends
Restriction Enzymes are the “Scissors” for DNA
Nerd Words
DNA Ligase: Used in replication
joins fragments
enzyme to join DNA fragments
used in DNA replication
(doubling DNA in interphase)
DNA ligase is the “glue” used in DNA Technology
joins sugar-phosphate backbone
DNA ligase pastes DNA together
Nerd Words
Recombinant DNA: made by combining DNA
from different sources
Transgenic: DNA from different species
(usually unable to breed together)
Plasmid: loop of DNA separate from chromosome
Plasmids are common
In bacteria
Cisgenics
adding genes from closely related organisms (often
within a species)
Another Nerd Word
Intragenics: like cisgenics – i.e. organisms
closely related and able to breed – but using
technology to make custom combinations of
genes
Nerd Words
“Amplifying DNA”: making copies of DNA
Why?
Getting more DNA to run tests
Detecting Mutations
Crime Scene
Paternity Case
Amplifying DNA: the basic idea
cut DNA into small pieces
Isolate fragment you want (usually a gene)
Make many copies of this fragment
Amplifying DNA: 2 methods
Making Many Copies of a piece of DNA (gene)
1. With Bacteria
put DNA into a bacteria
get bacteria to multiply, making more DNA
2. Polymerase Chain Reaction (PCR)
Copy DNA outside of a cell
uses heating and cooling (more info later)
Nerd Words
DNA cloning
Putting recombinant DNA into a cell so it
will be copied when the cells
Often used when studying genetic disorders
Amplifying DNA with Bacteria
Modified Bacteria: Lots of uses
• We currently use genetically modified bateria to make
insulin
blood-clotting proteins for hemophiliacs
clot-dissolving enzymes for stroke victims
Can use as a vector to transfer genes
Fixing Disease
Example: Person has bad copy/copies of gene
Give a good copy of gene
symptoms reduced/eliminated
“Gene Therapy” = Genetic Manipulation to
reduce symptoms of
a disease
Genomic Editing
Scissors: restriction enzymes
Smart scissors: zinc finger nucleases & TALENS
Precision editing: remove one allele and replace
with another
example: removing CCR5-Delta32
Making T-cells that are immune to HIV
Polymerase Chain Reaction
polymerase chain reaction (PCR)
amplifying DNA outside of cells
(faster than growing bacteria)
Why?
Need more DNA than you have to run test
When?
medical diagnostics, forensics,
paternity testing, and paleoanthropology to
Polymerase Chain Reaction
Goal: make billions of copies of a targeted
sequence of DNA
Requires:
Template DNA (stuff to be copied)
DNA polymerase (special high temp)
DNA primers (synthetic)
Nucleotides (ACGT)
VERY GOOD TEMPERATURE CONTROL
Temperature control in PCR
Heat DNA up
hot enough to separate hydrogen bonds
separates hydrogen bonds of rungs
not hot enough to separate sugar-phosphate
Cool back down, then repeat
PCR song
DNA Technology
Personalized medicine (custom treatments)
Gene therapy
Genetic Engineering
Adding one or more genes
Permanently modifies gene/tissue/organism
Genetically Modified Organism (GMO)
Created with Genetic Engineering
Genetic Engineering
• Transgene: gene introduced into GMO
transgenic organism: Another name for a GMO
Example: green fluorescent protein (GFP)
rabbit, fish, monkey, etc.
• Vectors: ways to put new genes into a cell:
– Plasmids
– Viruses
– Gene guns (shoot DNA directly into cell….usually used for plants)
GMOs: Why make them
• Make lots of of a gene product
therapeutic or commercial value
• Change organism to increase productivity or
performance
DNA Fingerprinting
• DNA fingerprinting: finding DNA unique to
species or individual
Forensics (CSI)
Paternity Test
• Looks at areas of DNA known to have lots of
variation
Cloning Plants: Easy
• Take a cutting
• Grow a new plant
• We’ve been doing this for centuries.
• Most animals cannot be reproduced this way
Cloning of Animals
• Reproductive cloning: making animals that are
genetically identical one organism with useful
characteristics
• Cloning: three-step process
1. removing the nucleus from an egg
2. Fuse this egg with a somatic cell (source of nucleus)
3. Put embryo into surrogate mother
Cloning: The ugly side
• High failure rate
Example: cloned rat (129 embryos, 3 rats)
• May have defects causing Short life span
Dolly the sheep (???)
Pyrenean Ibex (7 minutes, bad lungs)
• NOT IDENTICAL!!!! (Just has identical DNA)
Brahma Bull
Human Gene Therapy
• Gene therapy: fix disorders by altering gene function
• Giving people the correct version of a gene
• Somatic cell gene therapy – not as controversial
• Germ cell gene therapy – much more controversial
• RNA interference (RNAi) (the book mentioned it!!!)
tricking cells into shutting genes down
Human Gene Therapy
• In 1990, Ashanthi DeSilva was the first human to
receive gene therapy
• Two bad copies of a gene.
• White blood cells removed
• WBC infected by a virus containing a good copy of
gene
• WBC put back into body
Human Gene Therapy
• RNA interference (RNAi) (the book mentioned it!!!)
tricking cells into shutting genes down
Make a piece of a gene that looks like double stranded
(viral) RNA.
Cell destroys the “viral” RNA, and any similar RNA
all the mRNA of gene you want to shut down
Gel Electrophoresis Sorts
DNA Fragments by Size
• We use electricity to move DNA
Sugar-phosphate backbone has charge
• DNA moves through gel
• Little pieces move faster than big ones
Cut with restriction enzymes
Sorting Fragments of DNA
• We can sort them even if they are only 1
nucleotide longer
• Can determine A, C, G, T
• Automated sequencing machines
– identify over a million bases per day,
We “borrowed” our tools
• Restriction enzymes – used by bacteria to
destroy viruses
• DNA ligase – used by lots of stuff to join DNA
fragments during DNA replication
• High temperature DNA polymerase – used by
archea that live in hot springs
• Plasmids – used by bacteria to transfer genes
Ethics:
(Stuff people get worked up about)
• Do we have the right to alter DNA of other
species?
• Are there some species we should not alter?
Food?
Pets?
Primates?
Ethics: (Stuff people get worked up about)
• Not just biological issues
Social issues
Political issues
Medicine: “do we have the right…”
Farming: “is this sustainable….”, “will this harm….”
“will every farmer be forced to….”
“do people want to eat….”
Monsanto: Love it or Hate it
vs
Genetically Engineered Foods
Are they dangerous? Should we test? Should we label?
some of this is addressed later: always new info
Why do we think selectively bred crops are any afer?
Lenape potato: solanine
GMOs: judge case by case
• Genetically modified crops
harmful effects on soil, water, or animals?
are they safe?
Example: “roundup ready” crops (more poison in soil)
vs.
BT versions of crops (less poison in soil)
Encouraging more poison use is probably a bad idea
Can we control GMOs?
Genes can spread (wind blows pollen)
people who don’t want to grow it might to so
(and get sued by monsanto)
What if you can’t eat GMO corn?
can you be sure that the
corn you buy is free from
the things that are bad
for you
http://rameznaam.com/2013/04/28/the-evidence-on-gmo-safety/
Scientific Consensus: SAFE!
Long term studies (yes they exist)
Superweeds (develop regardless of GMOs)
more info later
Harm to plants and animals (biodiversity)
“There are no long term studies…”
Yes there are:
multi-year studies
fish, cows, mice
multi-generational
TEN generations in birds
three generations in rats
No, we cannot prove something is always safe.
OTOH, we have not been able to show bad effects
Claim: GMOs cause superweeds
More use of pesticides can cause more hardy pests
Partially true….
Truth: Weed killers cause superweeds
Life sometimes
finds a way
People use poisons
Weeds mutate, some are immune
USING POISON MAKES POISON-RESISTANT WEEDS LIKELY
70
Poison
glyphosate
atrazine
60
50
40
GMO to resist
round-up ready
NONE
30
20
Resistant weeds
24 species
64 species
http://www.nature.com/news/case-studiesa-hard-look-at-gm-crops-1.12907
10
0
roundup
atrazine
Biodiversity
Human impact always causes winners and losers
non-target species are going to be affected
especially ones similar to targeted pest
Spraying kills everything
BT GMO kills things that
bite parts of the corn plant
Biodiversity
Yes, related species can be killed
pollen on wind: monarch
effects less than expected
plant milkweed elsewhere
Net Effect:
Pesticides: 30% reduction (Stephen Naranjo)
number of species increased
Legal Regulation of GMOs
Bans: why?
Mandate pollen containment: greenhouses
Labels: Yes, labels are coming (popular demand)
shape them instead of opposing them
information, not fear
like ingredients label
Clicker Questions
CHAPTER 16
DNA Technology
Concept Quiz
What is an advantage of restriction
enzymes?
A.They cut DNA into manageable pieces.
B.They cut at a specific sequence and, therefore,
give consistent results.
C.They leave sticky ends, which can be used in
cloning.
D.All of the above
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Not understanding the material?
Remember that the TLCC has
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