Chapter 12 - Genetic Engineering - Bizland.com

deadstructureBiotechnology

Dec 14, 2012 (4 years and 10 months ago)

175 views

Chapter 12


“Genetic Engineering”

Charles Page High School

Stephen L. Cotton

Section 12
-
1

Modifying the Living World


OBJECTIVES:


Describe breeding strategies
that have been used to
modify living things.

Section 12
-
1

Modifying the Living World


OBJECTIVES:


Explain how mutations in
organisms can be useful to
humans.

Section 12
-
1

Modifying the Living World


Humans are always trying to
improve the world around us


Farmers and Ranchers
-

have
tried to improve the organisms
with which they work


select the most productive
plants or animals

Section 12
-
1

Modifying the Living World


Selective Breeding can increase
productivity


Forms of selective breeding:


inbreeding and hybridization


Selective breeding is the oldest
and most obvious way to
improve a species

Section 12
-
1

Modifying the Living World


A few individuals are “selected”
to serve as the parents of the
next generation


these are individuals that have
some desirable characteristic


increase milk production in
cattle, or certain flower colors

Section 12
-
1

Modifying the Living World


Luther Burbank

(1849
-
1926) is
probably the world’s foremost
selective breeder


more than 250 new varieties of
fruit, but also included other
plants such as the daisy and
famous Burbank potato

Section 12
-
1

Modifying the Living World


Once a desirable trait is achieved,
the next step is to keep it


Inbreeding

is one way to do this


crossing individuals with similar
characteristics
-

“purebreds”


often closely related to each
other

Section 12
-
1

Modifying the Living World


Inbreeding useful; but certain risks


the chances of recessive genetic
defects showing up is much
greater


deformity in joints & blindness in
German shepherds and golden
retrievers from repeated use

Section 12
-
1

Modifying the Living World


Hybridization

-

a cross between
dissimilar individuals


may even involve crossing
different (but related) species


Hybrids

are often healthier than
the parents; this is known as
“hybrid vigor”

Section 12
-
1

Modifying the Living World


New hybrids may have:
a) increased disease resistance,
b) more yield per acre, and
c) more nutritional value


modern hybrid corn produces
as much as 10 times the yield
per acre of older varieties

Section 12
-
1

Modifying the Living World


Note Figure 12
-
2, page 248


As useful as selective breeding
is, it is confined to characteristics
that
already exist

in the
population


Mutations

can produce
new

inherited characteristics

Section 12
-
1

Modifying the Living World


If these new characteristics are
desirable, breeders can use
selective breeding to produce an
entire population

that have these
characteristics


But, can we always wait for a
beneficial mutation to appear?

Section 12
-
1

Modifying the Living World


We may increase the chances
(artificially) to cause a mutation


done with substances called
“mutagens”


examples include radiation and
certain chemicals

Section 12
-
1

Modifying the Living World


Many mutations are harmful; but
with luck a few mutants with
desirable characteristics may be
produced


Mutagenesis

(using mutagens to
increase mutation rate) is
particularly useful with bacteria

Section 12
-
1

Modifying the Living World


Their small size allows millions to
undergo mutagenesis, thereby
increasing the chance of
producing a useful mutant


many useful strains have been
developed, even bacteria that
can digest oil to help clean up
oil spills!

Section 12
-
1

Modifying the Living World


Note Figure 12
-
4, page 249
showing a) seedless oranges
and b) hairless mice