Biology Chapter 12


14 déc. 2012 (il y a 8 années et 7 mois)

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Chapter 12

and Genomics



the production of genetically
identical copies of DNA, cells, or
organisms through asexual means

(i.e., single parent)

Plants are Cloned from a Single Cell

Cloning Carrots

Animals are Cloned Using

a Donor Nucleus

Reproductive cloning
produces individual
that are a genetic copy of the original

Therapeutic cloning

produces mature cells
of various cell types

Purposes of therapeutic cloning

learn more about how specialization of cells

provide cells and tissues that could be used
to treat human illnesses

Reproductive Cloning

Therapeutic Cloning

Animal Cloning has Benefits and

First mammal to be successfully cloned
was Dolly, the sheep

Since Dolly, mice, cats, dogs, and monkeys
have been cloned

Animal Cloning has Benefits and

Cloning Benefits

increases knowledge of gene interactions and
embryological development

may be the only way to save endangered

can be used to repair organs

combat cancer

fight disease

Animal Cloning has Benefits and

Cloning Drawbacks

because the donor’s mitochondrial DNA is not
passed to the clone, premature aging may

the “age” of the donor’s telomeres may also
cause premature aging

can concentration genetic defects

mutation rate is higher in clones

regulation of gene expression is abnormal

may create ethical issues

DNA can be Isolated and Cloned

Gene Cloning

produces many identical
copies of the same gene

recombinant DNA (rDNA)

has DNA from one or more different sources

To create rDNA a

is used to introduce
DNA into a host cell, which is often a

One common vector is a
a small
chromosomal piece of DNA found in







Specific DNA Sequences can be Cloned

Polymerase Chain Reaction (PCR)

create copies of a segment of DNA quickly
in a test tube

Commonly used to amplify small
amounts of DNA

Copies of DNA


per PCR cycle

one original

Specific DNA Sequences can be Cloned

DNA Fingerprinting

detects how many
times a short sequence is repeated

People differ by how many repeats they have
at particular locations

DNA fingerprinting of specific base repeat units at
different genome locations establishes paternity:

Male 1 is the father

Bacteria can be Genetically Modified to
Make a Product or Perform a Service

Organisms are genetically modified (GM)
in order to produce specific products

These are called transgenic organisms

They produce
biotechnology products

: insulin, human growth hormone,
and hepatitis B vaccine

Making Cheese via Genetic Engineering

making industry was dependent
upon rennet, which consists of two
enzymes: chymosin and bovine pepsin

Traditionally, rennet was collected from the
stomach lining of calves, but it became
scarce as veal industry declined

Making Cheese via Genetic Engineering

Gene responsible for formation of
chymosin was isolated from calf cells,
cloned and inserted into the genome of
several organisms

Cheese containing chymosin was the first
food dependent on genetic engineering in
U.S. history

Plants are Genetically Modified to Increase
Yield or to Produce a Product

Corn, potato, soybean, and cotton plants
have been engineered to be resistant to
insect predation or widely used herbicides

Crops with other improved agricultural and
quality traits are desirable

Soybeans have been developed that mainly
produce the fatty acid oleic acid, a change
that may improve human health

Genetically modified

crops of the future

Are Genetically Engineered Foods Safe?

FDA study

most people believe genetically
engineered foods might offer benefits, but feared
unknown long
term health consequences

Scientists are concerned about the potential
drawbacks to the planting of GM corn

Resistance among populations of the target pest

Exchange of genetic material between the transgenic crop
and related plant species

GM crops’ impact on nontarget species

Nonetheless, USDA reports that U.S. farmers in 2004
planted genetically engineered corn on 45% of all
corn acres

Animals are Genetically Modified to

Enhance Traits or Obtain Useful Products

is the use of animal
organs, instead of human organs, in
transplant patients

Pigs genetically modified so their organs are
less likely to be rejected by humans?

A procedure
for producing
many female
clones that
yield the same

GM mice showed

that male gender
is due to



A Person’s Genome can be Modified

Gene Therapy

insertion of foreign gene into
human cells for treatment of a disorder

Ex Vivo Gene Therapy

To treat SCID, bone marrow stem cells are removed
from the patient and infected with a virus that carries
a normal gene for the enzyme

In Vivo Gene Therapy

The gene needed to cure cystic fibrosis is sprayed
into the nose or delivered to the lower respiratory
tract by a virus or by liposomes

Limited success for these so far.

Sites of
ex vivo
in vivo
therapy to cure
the conditions

Gene Therapy Trials have Varying
Degrees of Success

Severe Combined Deficiency Syndrome (SCID)

Children able to soon go home

After three years, 3 of the 10 children developed
leukemia and needed chemotherapy

Skin Cancer

The skin cancer melanoma accounts for only
about 4% of skin cancer cases, but it is also the
most serious and most aggressive type.

After one year, 2 of 15 patients remained disease

A procedure for
modifying the
white blood cells
to fight cancer

The Human Genome Sequence

Human Genome Project (HGP)

determined the order of the 3 billion bases
in our
(all of

our genes)

How did they do it?

Developed a laboratory procedure to analyze
a short sequence of base pairs

Instruments were developed that increased

The Human Genome Sequence

Many small regions of DNA that vary among
individuals were identified during the HGP

Most of these are
single nucleotide
polymorphisms (SNPs)

Personal Genome Project

Sequence every person’s genome

Possible benefits and drawbacks?

New Cures on the Horizon?

Possibility A: Many new medicines

Now researchers can take a more systematic
approach to finding effective medicines

Possibility B: Medicines will be safer due
to genome scans

Use of a gene chip will quickly and efficiently
provide knowledge of your genetic profile

New Cures on the Horizon?

Possibility C: Longer and healthier life

Preembryonic gene therapy may become
routine once we discover the genes that
contribute to a longer and healthier life

Possibility D: Design your children

It may be possible to cure genetic disorders
before a child is born by adding a normal gene
to any egg that carries a mutant gene

Therapeutic Use of Stem Cells

Stem Cell


use of 11 yr old boys own stem cells

to rebuild damaged trachea

Proteomics and Bioinformatics are New


collection of all proteins in the

is the study of the structure,
function, and interaction of cellular proteins

Proteomics and Bioinformatics are New

is the application of
computer technologies to the study of the

Scientists hope to find cause
relationships between various genetic profiles
and genetic disorders caused by multifactorial


Research into the nature and organization of
genes in various organisms allowed
geneticists to produce recombinant DNA

A knowledge of transcription and
translation enables scientists to
manipulate the expression of foreign
genes in organisms


These breakthroughs have spurred a
biotechnology revolution

Bacteria and eukaryotic cells are now
used to produce vaccines, hormones,
and growth factors for use in humans


Although some people are fearful about the
consequences of biotechnology on
ecological and human health, no serious
problems have surfaced thus far

Biotechnology offers the “promise” of
curing some human genetic disorders,
such as muscular dystrophy, cystic
fibrosis, hemophilia, and many others