Chapter 13- Genetic Engineering

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23 Οκτ 2013 (πριν από 4 χρόνια και 2 μήνες)

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1

Chapter 13
-

Genetic Engineering


13
-
1

*
What do Goldendoodles, Labradoodles, and Puggles have in
common?


*
All are a result of
Selective Breeding
-

allowing only animals with
desired characteristics to produce the next generation.

Nearly all domestic animal
s (cats, horses, etc) and lots of crop plants
have been produced by selective breeding

*
Important Historical Example: Luther Burbank

(American)

-
developed disease
-
resistant Burbank potato


-
exported to Ireland to help fight potato blight and


other diseas
es


Hybridization
-

crossing similar organisms to bring together
the best of both organisms


Hybrids produced are often hardier than parents


Inbreeding
-
continued breeding of individuals with similar
characteristics


good
-

maintaining certain characteristic
s

bad
-

genetic defects
-

greater risk of recessive alleles
joining and causing problems (ex: blindness, hip
problems)

Reminder: What is a mutation?


-
changes in genetic material

-
Mutation
s:

-
ultimate source of genetic variation.

-
inheritable changes in DNA

-
Breeders can increase genetic variation in a population by
increasing mutations.


-
Mutations occur spontaneously


-
can increase rate by using radiation and chemicals





2

New Bacteria

-
small: millions can be treated with radiation or chemicals
at same tim
e



-
increases chance of producing useful mutant

-
ex: produced bacteria that digest oil


used to clean
up oil spills


New Kinds of Plants


-
Polyploidy
-
organism w/extra set of chromosomes



-
usually fatal in animals


-
Plants=
larger and stronger


-
ex: cro
ps
-

bananas and many citrus fruits


13
-
4 Genetic Engineering

Genetic Engineering makes it possible to transfer DNA
sequences (including whole genes) from 1 organism to
another


From animals to plants????



1986
-

scientists isolated gene for luciferase




-
enzyme
-

makes fireflies glow




-
inserted into tobacco cells




-
plant glowed in dark

-
showed basic mechanisms of gene expression are
shared by plants and animals


Transgenic Organisms
-

contain genes from other species


Biotechnology
-

manipulation of organ
isms to do practical
things and to provide useful products


Transgenic Microorganisms

-
Proteins:
insulin, growth hormone, clotting factor

-
used to treat serious human diseases and
conditions


3



-
used to be expensive and rare

-
Bacteria transformed with human

protein now
produce these compounds

-
now
cheaper and easier


Transgenic Animals


-
used to study genes and improve food supply

-
mice
-

immune systems made to act like human
immune systems


-
allows scientists to study effects of diseases

-
livestock (cattle,

pigs)
-

some now have extra copies
of growth hormone genes


-
grow faster
;
produce leaner meat (less fat)

-
Researchers trying to produce chickens resistant to
bacteria that causes food poisoning.


Transgenic Plants

(also called Genetically Modified
-
GM)

-
Ye
ar
2000
-

52% of soybeans and 25% corn grown in U.S.
were

transgenic or genetically modified (GM)


-
contain natural insecticide

-
resist chemicals

kill weeds w/out hurting crop

-
Rice with Vitamin A
-

important for human health


-
some countries rely on rice a
s main food



= sure to get vitamin = improve health?

Cloning

-
clone
-

member of
a population of genetically identical
cells produced from a single cel
l

-
bacterial clones
-

easy to grow
;
-
multicellular clones
(animals)
-

more difficult


-
1997
-

Dolly

the sheep
;
scientist Ian Wilmut

-
figure 13
-
13


-
cloning may help save endangered species


-
problems: genetic defects and healt
h problems