Section 27-3: Genetic Engineering - Vista del Lago High School

roachavocadoΒιοτεχνολογία

14 Δεκ 2012 (πριν από 4 χρόνια και 4 μήνες)

256 εμφανίσεις

Chapter 13: Genetic Engineering

Calif. grades 9
-
12 Biology/Life Science standard:
Genetics 5c,d,e

Review


kinds of mutations


causes of mutations


gene vs. chromosomal
mutations


Show how plant and animal
breeders improve crops and
animals.


Explain how organisms are cloned.


Show how genetic engineering
benefits people.

What we’ll
learn:

Man has been improving plants and
animals for thousands of years by
utilizing
genetic variation
.


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

13
-
1

To do this, he has used

selective breeding:

Selective breeding

Many years

To maintain the desired
characteristics of a line of
organism, breeders often use a
technique known as:

Inbreeding

= continued
breeding of individuals with
similar characteristics.

13
-
1

Problem with inbreeding

Increases the chance of
bringing together 2
recessive alleles for a
genetic defect.

13
-
1

Problem examples:


Joint problems in German
Shepherds


Eye problems


Irish potato blight, U.S.
corn crop (reduced
variation in population)

13
-
1

Sterility problems, can’t reproduce



Extinction

Hybridization

Crossing dissimilar individuals
to bring together the best
of both organisms.

Hybrids are often

hardier than

the parents

13
-
1

Examples of hybrids


Mule (superior to parents
in endurance, strength,
disease resistance)


Most crop plants


Tangelo

13
-
1

Hybrids


mule (horse x male donkey)

x

13
-
1

Tangelo

Tangerine

X

Pumelo

×

Hybridization also can help
save endangered species:


Florida panthers x Texas
cougars

Liger:

a

cat born from
the breeding of
a
male lion

and a
female tiger
.

Zonkey

Gullamute

Increasing Variation


Selective breeding requires
genetic
variation
.


Variation can be increased by
inducing mutations.



Radiation


Chemicals

Mutations


Naturally occurring mutations can
be useful to plant and animal
breeders.

Parent Navel Orange Tree

20
-
2

Increasing Variation


New kinds of bacteria






New kinds of plants


Polyploidy usually fatal in animals,
but produces larger and stronger
plants.

Tetraploid (4n) hybrid Easter Lily

13
-
2: Manipulating DNA

13
-
2

Scientists use their
knowledge of the
structure of DNA and
its chemical properties
to study and change
DNA molecules.


Scientists use different 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


13
-
2

The Tools of Molecular
Biology


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.


When the power is turned on, the
negatively
-
charged DNA molecules
move toward the positive end of the
gel.

13
-
2

The Tools of Molecular
Biology


Gel electrophoresis can be used to
compare the genomes of different
organisms or different individuals.


It can also be used to locate and
identify one particular gene in an
individual's genome.

13
-
2

The Tools of Molecular
Biology

Gel Electrophoresis

13
-
2

The Tools of Molecular Biology

First, restriction
enzymes cut
DNA into
fragments.


The DNA
fragments are
poured into wells
on a gel.

The Tools of Molecular Biology


An electric voltage
is applied to the gel.
This moves the DNA
fragments across
the gel.


The smaller the
DNA fragment, the
faster and farther
it will move across
the gel.

The Tools of Molecular Biology


Based on size,
the DNA
fragments make a
pattern of bands
on the gel.


These bands can
then be compared
with other
samples of DNA.

Using the DNA Sequence


Making Copies



Polymerase chain reaction (PCR)

is a
technique that allows biologists to
make copies of genes.


A biologist adds short pieces of DNA
that are complementary to portions of
the sequence.

13
-
2

Using the DNA Sequence


DNA is heated to separate its two
strands, then cooled to allow the
primers to bind to single
-
stranded
DNA.


DNA polymerase starts making copies
of the region between the primers.

13
-
2

DNA heated to
separate strands

PCR cycles

DNA copies

1

2

3

4

5 etc.

1

2

4

8

16 etc.

Polymerase Chain Reaction (PCR)

DNA polymerase adds
complementary strand

DNA fragment
to be copied

In
genetic engineering (GE)
,
biologists make changes in
the DNA code of a living
organism.


13
-
3

3 major steps in GE:


1. Isolate a gene


(find a gene you want and take it out
of host DNA)


2. Make recombinant DNA


(put the gene into another piece of
DNA)


3. Insert the DNA


(put the new DNA into something
that can transcribe it and make the
protein)


1. Isolate gene

2. Make recomb. DNA

3. Insert DNA

Make copies

13
-
3

Step 1: Isolating a gene

Restriction enzyme =
Proteins

used to cut DNA
molecules at specific places.

13
-
3

Each
restriction enzyme

cuts DNA at a
specific sequence of nucleotides.


Step 2: Making recombinant DNA

DNA fragment must be
combined with something for
it to work.

Plasmid

= small ring
-
shaped
bacterial DNA segment.

13
-
3

Plasmid

Gene of interest

13
-
3

Plasmids

Step 2: Making recombinant DNA

DNA fragment inserted into plasmid.

DNA is now

recombinant DNA


13
-
3

Recombinant DNA

DNA combined from 2 different
sources.


(example: Human + bacteria)


Step 3: DNA Insertion

Plasmids inserted into bacteria
which multiply into large numbers.



Clone

= genetically identical cells or
organisms

13
-
3

Applications/examples of
genetic engineering


Human insulin, clotting factor


Anti
-
viral drugs like
interferon


Correcting genetic disorders
(gene therapy)


Transgenic crop plants
(tomatoes that ship better)

13
-
4

Applications


Forensics


Solving crimes


Identifying bodies, familial
relationships

13
-
4


Would it be right for parents to
engineer children’s physical and
intellectual traits?


Who decides what traits are right?


Some insurance companies
already deny coverage for people
with
predisposition

to disease.

Ethics:

Restriction enzymes are used to



extract DNA.



cut DNA.



separate DNA.



replicate DNA.


During gel electrophoresis, the
smaller the DNA fragment is, the



more slowly it moves.



heavier it is.



more quickly it moves.



darker it stains.


The DNA polymerase enzyme Kary
Mullis found in bacteria living in the
hot springs of Yellowstone National
Park illustrates


genetic engineering.



the importance of biodiversity to
biotechnology.



the polymerase chain reaction.



selective breeding.

A particular restriction enzyme is
used to



cut up DNA in random locations.



cut DNA at a specific nucleotide
sequence.



extract DNA from cells.



separate negatively charged DNA
molecules.


During gel electrophoresis, DNA
fragments become separated
because



multiple copies of DNA are made.


recombinant DNA is formed.



DNA molecules are negatively
charged.



smaller DNA molecules move
faster than larger fragments.