Download Genetic Engineering Notes 2017

GENETIC ENGINEERING
Chapter 9
CHANGING THE LIVING WORLD

Selective Breeding
Allows only those organisms with desired characteristics
to produce the next generation
 Nearly all domestic animals and most crop plants have
been produced by selective breeding.


Hybridization
Crossing of dissimilar individuals to bring together the
best of both organisms
 Hybrids, the individuals produced by such crosses, are
often hardier than either of the parents.


Inbreeding
Continued breeding of individuals with similar
characteristics
 Helps to ensure that characteristics that make each
breed unique will be preserved
 Serious genetic problems can result from excessive
inbreeding.

CHANGING THE LIVING WORLD

Increasing Variation
Accomplished by inducing mutations into a population
 Mutations occur spontaneously, but breeders can
increase the mutation rate by using radiation and
chemicals.
 Breeders can often produce a few mutants with desirable
characteristics that are not found in the original
population.
 Beneficial?


Introducing mutations has allowed scientists to develop
hundreds of useful bacterial strains, including bacteria that can
clean up oil spills.
MANIPULATING DNA

Scientists use different kinds of techniques to:
extract DNA from cells
 cut DNA into smaller pieces
 identify the sequence of bases in a DNA molecule
 make unlimited copies of DNA


Genetic Engineering:

biologists make changes (alterations) in the DNA code of
a living organism
MANIPULATING DNA

DNA Extraction


The cells are opened and the DNA is separated from the
other cell parts through a simple chemical procedure.
Cutting DNA
Most DNA molecules are too large to be analyzed, so
biologists cut them into smaller fragments using
restriction enzymes.
 Each restriction enzyme cuts DNA at a specific sequence
of nucleotides.

Recognition sequences
DNA
sequence
Restriction enzyme EcoR I
cuts the DNA into fragments
Sticky end
MANIPULATING DNA

Separating DNA

In gel electrophoresis, DNA fragments are placed at one
end of a porous gel, and an electric voltage is applied to
the gel
Power
source
DNA plus restriction
enzyme
Longer
fragments
Shorter
fragments
Mixture of
DNA
fragments
Gel
Gel Electrophoresis
•First,
restriction
enzymes cut DNA into
fragments.
•The DNA fragments are
poured into wells on a
gel.
DNA plus
restriction
enzyme
Mixture of
DNA
fragments
Gel Electrophoresis
Gel
•An
electric voltage is
applied to the gel.
•The
smaller the DNA
fragment, the faster
and farther it will move
across the gel.
Power
source
Power
source
Longer
fragments
Shorter
fragments
Gel Electrophoresis
MANIPULATING DNA

Making Copies of DNA
Polymerase chain reaction (PCR) is a technique that
allows biologists to make copies of genes.
 Small amounts of DNA can be multiplied making it
easier to analyze.

CELL TRANSFORMATION

Transforming Bacteria
During transformation, a cell takes in DNA from outside
the cell. The external DNA becomes a part of the cell's
DNA
 Steps:


Foreign DNA is first joined to a small, circular DNA molecule
known as a plasmid.
 Found naturally in some bacteria
 Very useful for DNA transfer.
Recombinant
DNA
Gene for human
growth hormone
Gene for human
growth hormone
Human Cell
Bacterial
chromosome
Sticky
ends
DNA
recombination
Bacteria cell
Plasmid
Bacteria cell
containing gene for
human growth
hormone
DNA
insertion
APPLICATIONS OF GENETIC ENGINEERING

Transgenic Organisms
An organism described as transgenic, contains genes
from other species.
 Uses


Microorganisms
 Transgenic bacteria produce important substances useful for
health and industry.
 Inexpensive
 Easy to manufacture
 Have been used to produce:



insulin
growth hormone
clotting factor
APPLICATIONS OF GENETIC ENGINEERING

Transgenic Organisms

Uses

Animals
 Have been used to study genes and improve the food supply
 Mice have been produced with human genes that make their
immune systems act like those of humans.

Allows scientists to study the effects of diseases on the human
immune system without having to study them ON humans.
Researchers are trying to produce transgenic chickens that to
be resistant to bacterial infections that cause food poisoning.
 Plants
 Transgenic plants are now an important part of our food
supply.
 Many of these plants contain a gene that produces a natural
insecticide, so plants don’t have to be sprayed with pesticides.

APPLICATIONS OF GENETIC ENGINEERING

Cloning
A clone is a member of a population of genetically
identical cells produced from a single cell.
 In 1997, Ian Wilmut cloned a sheep called Dolly

Dolly and Bonnie