should we modify food at the genetic level? - District 158


12 déc. 2012 (il y a 9 années et 1 mois)

355 vue(s)

QUIZ (10 points)

1. What was the purpose of the salt (2 pts)?

2. What was the purpose of the soap (2 pts)?

3. What was the purpose of meat tenderizer in
our lab (2 pts)?

4. Why was the ethanol cold

poured slowly
into the tube (4 pts)?

Genetic Technology

What is it?

Chapter 13

Page 341

Genetic Technology

GT=Manipulation of genes to achieve a desired outcome

Selective breeding

allows people to alter traits of certain

Dogs and cats are the result of hundreds of years of genetic
technology (and mutations)

Genetic engineering

= cutting DNA from one organism and
inserting it into another

Recombinant DNA

= DNA that is made by recombining
fragments of DNA from different sources

transgenic organism

is one that contains functional
recombinant DNA


refers to the artificial replication of a gene or

Genetic Engineering

How does DNA get cut?

Restriction enzymes (REs)

= bacterial proteins
that can cut both strands of the DNA molecule

There are hundreds of REs that cut DNA in
different places

Cutting the DNA produces “sticky ends”

Once the DNA is cut it can be inserted into
another organism

Let’s see how restriction enzymes (aka
restriction endonucleases) work

The Use of Bacteria

Bacterial DNA is in a ring shape (

Bacteria are commonly used to transfer
DNA from one organism to another

In the case of the glowing tobacco plant in
your book, bacteria was used to transfer
firefly DNA into the plant DNA

The means by which DNA is carried from
one species to another is called a

Biological vectors include bacteria & viruses

Mechanical vectors are micropipettes and
microscopic bullets shot from a gene gun

Recombinant DNA

Recombinant DNA

technology was
discovered in 1973 by Stanley Cohen and
Herbert Boyer using frog RNA

Let’s see how they did it

E.coli is often used in biology because of its
rapid life cycle and ubiquity

Bacteria plasmids have been recombined to
produce human insulin, human growth
hormone, vaccines, and mainly antibiotics

Bacteria have also been used to prevent ice
forming on crops

Let’s take a look at how vaccines are made

Transgenic Organisms

Any organism with foreign DNA is said to be

Transgenic organisms are also known as
Genetically Modified Organisms (GMOs)

GMOs include the foods you eat

Corn, beans, and many other crops have been
modified to resist herbicides, grow bigger,
faster and even tastier, last longer, and include
more vitamins and minerals

Golden rice contains 23 times more beta
carotene than white rice

GMOs have been a subject of controversy for
years…should we modify food at the genetic

Glofish are the first publicly available
transgenic animals


Let’s take a look at how cloning a gene works

Cloning can be used to create more cells too

Skin cells can be cloned on agar plates to be used
for burn victims

Cloning can create organisms like “Dolly” the sheep

Cloned organisms are 99.99% the same as the
donor (minus mitochondrial DNA)

Clones could be used to save endangered animals

Cloning could also be used to make extinct animals

Cloning humans could be done for harvesting
organs and tissues

What other uses could human clones serve?

Should we be able to clone humans?

Genetic Technology

Genetics has become part of TV and movies, etc.

The complementary DNA sequence for CTAATGT is the
1997 movie about genetically engineered “designer babies.”

Should we be able to change our baby’s DNA in

The Simpsons had an episode about genetically modified
food. What is the product farmer Homer made?

Video games have genetically altered characters

Spiderman is the result of being bitten by a genetically
altered “super spider.”

DNA Fingerprinting

Discovered in 1985 by Sir Alec Jefferys

The background of these slides is an image of a DNA

DNA fingerprinting is used to determine criminals and
victims from DNA samples

It can be used to identify babies in paternity cases

DNA can also be used to identify dead bodies

Very little DNA is necessary for a fingerprint thanks to the
Polymerase Chain Reaction


Let’s see how it works

PCR uses very small amounts of DNA, a polymerase
enzyme, and free nucleotides to make many copies of a
segment of DNA

DNA Fingerprinting

How it works

DNA is negatively charged (because of the phosphate
sugar backbone)

Gel electrophoresis

is the process of moving electrically
charged DNA through an agarose gel using an electric

Steps to creating a DNA fingerprint:

1. Obtain DNA sample

2. Use PCR to create numerous amounts (purify)

3. Cut the DNA using restriction enzymes (RE)

4. Place DNA fragments in a gel

5. Provide current to move the DNA from


6. Smaller fragments move farther/faster

DNA Fingerprinting

DNA Fingerprinting

DNA Fingerprinting

Let’s take a look at a virtual extraction lab

There are different methods of cutting the DNA


RFLP (1980s


AFLP (1990s


STR (current)

How accurate is current DNA fingerprinting?

One out of a quintillion 1,000,000,00

Seeing as how there aren’t even 7 billion people on this
planet, that makes it pretty accurate

DNA Fingerprinting

Minisatellite DNA

are repetitive sequences found in
DNA that don’t code for a protein

Everyone in the world has their own pattern of this
type of DNA

When restriction enzymes cut up your DNA, the
number of pieces and the sizes of those pieces are
unique (like a regular fingerprint)

If your DNA strand is cut by restriction enzymes it
leaves behind pieces of DNA

Those pieces of DNA are different sizes

The sizes are measured in base pairs (bp)

The fragment sizes and number of fragments is
different from everyone else in the world

A sticky end with only one row has no base pairs

DNA Fingerprinting

How to count
base pairs: