Chapter 15 Genetic Engineering Notes

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Oct 23, 2013 (3 years and 7 months ago)

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Honors Biology Chapter 15


Genetic Engineering


I.

Genetic Engineering and V
ariation

a.

Mutations are the source of biological diversity.

b.

Introduce mutations into populations to increase genetic variation.

c.

Biotechnology

is the application of a technological process, invention, or method to
living organisms.

i.

Selective Breeding


1.

H
umans choose organisms with wanted characteristics to produce the
next generation.

2.

This takes advantage of natural variation among organisms and

passes
wanted traits to offspring.

a.

breeds of dogs

b.

varieties of crop plants

ii.

Hybridization

crosses dissimilar individuals to bring together the best of both
parents in the offspring.

1.

Inbreeding

is the continued breeding of individuals with selected
chara
cteristics.

2.


It ensures that wanted traits are preserved, but can also result in
defects being passed on.

iii.

Radiation and chemicals can increase the mutation rate.

1.


Diverse bacterial strains have been bred from mutated lines.

2.

Drugs can prevent the separation

of chromosomes during mitosis,
leading to polyploidy in plants. Such plants may be larger or stronger
than their diploid relatives.

iv.

Copying DNA

1.


Genetic engineers can transfer a gene from one organism to
another to achieve a goal, but first, individual ge
nes must be
identified and separated from DNA.

2.

The original method (used by Douglas Prasher) involved several
steps:

a.

Determine the amino acid sequence in a protein.

b.

Predict the mRNA code for that sequence.

c.

Use a complementary base sequence to attract the
predicted
mRNA.

d.

Find the DNA fragment that binds to the mRNA.

3.

Once scientists find a gene, they can use a technique called the
polymerase chain reaction

to make many copies.

a.

Heat separates the DNA into two strands.

b.

As the DNA cools, primers are added to
opposite ends of the
strands.

c.

DNA polymerase adds nucleotides between the primers,
producing two complementary strands. The process can be
repeated as many times as needed.

II.

Changing DNA

a.

Recombinant DNA

molecules contain DNA from two different sources. Rec
ombinant
-
DNA technology can change the genetic composition of living organisms.

i.

Plasmids

are circular DNA molecules found in bacteria and yeasts; they are
widely used

by scientists studying recombinant DNA, because DNA joined to a
plasmid can be replicated
.


ii.

A
genetic marker

is a gene that is used to differentiate a cell that carries a
recombinant plasmid from those that do not.

b.

Transgenic Organisms

i.

Transgenic

organisms contain genes from other species.

ii.

They result from the insertion of recombinant DNA in
to the genome of the host
organism.

iii.

A
clone

is a member of a population of genetically identical cells.

c.

Agriculture and Industry

i.


Genetic engineers work to improve the products we get from plants and
animals.

1.

Plants

a.

Genetically modified crops may be more nutritious or higher
yielding.

b.

They may be resistant to insects, diseases, or spoilage.

c.

Some can produce plastics.

2.

Animals

a.

Genetically modified animals may produce more milk, have
leaner meat, or contain higher leve
ls of nutritious compounds.

b.

Transgenic salmon grow rapidly in captivity.

c.


Transgenic goats produce spider silk in their milk.

d.

Health and Medicine

i.

Recombinant DNA studies are leading to advances in the prevention and
treatment of disease.

1.

Examples

a.

vitamin
-
rich rice,

b.


human proteins made in animals,

c.

animal models of human disease (for research),

d.

bacteria that produce human insulin.

e.

Gene therapy

is the process of changing a gene to treat a disorder.

i.

G
ene therapy is still an experimental and high
-
risk techn
ique.

ii.

Genetic testing can identify hundreds of inherited disorders.

iii.

Not all genes are active in every cell.

iv.

DNA microarray

technology lets scientists study thousands of genes at once to
determine their activity level.

III.

Personal Identification

a.


DNA
fingerprinting

analyzes sections of DNA that may have little or no function but
that vary from one individual to another.

b.

DNA fingerprinting is used in
forensics

the scientific study of crime
-
scene evidence


to identify criminals. It is also used to identi
fy the biological father when paternity is in
question.

c.

Common ancestry can sometimes be determined using mitochondrial DNA (mtDNA) and
Y
-
chromosome analysis.

IV.

Profits and Privacy

a.


Most of the research in genetic engineering is done by private companies.

i.

They patent their findings and inventions to protect their investment and make
a profit.

ii.

The patents block other scientists from pursuing certain lines of research.

b.

In 2007, the Genetic Information Nondiscrimination Act was signed into law in the
United St
ates. It prohibits discrimination based on genetic information.



V.

Safety of Transgenics

a.

Proponents of genetically modified foods argue that GM crops are better, safer, and
higher yielding than conventional crops. GM crops require less land and energy to g
row,
and insecticides need not be applied to insect
-
resistant strains. Careful studies have
provided no support for concerns about the safety of GM crops.

b.

Opponents argue that the safety of GM crops has been neither adequately tested for
long
-
term use, nor

regulated. Patents on GM seeds may force small farmers out of
business. The resistance of GM plants to insects may harm beneficial insect species.
Resistance to herbicides may result in the overuse of toxic chemicals.

c.

Some states have introduced legislati
on to require that GM foods be labeled.

VI.

Ethics of the New Biology

a.


Few argue that gene therapy for curing disease is ethically wrong, but many ask the
question of how far genetic modification should go.

i.

Is it right to try to engineer children to have certa
in characteristics?

ii.

Should human cloning be allowed?