Blueprint of Life
Topic 22: Cloning
Biology in Focus, HSC Course
Glenda Childrawi, Margaret Robson and Stephanie Hollis
DOT POINT(s)
 identify how the following current reproductive
techniques may alter the genetic composition of a
population:
 artificial insemination
 artificial pollination
 Cloning (we will discuss this today)
 Process information from secondary sources to describe a
methodology used in cloning
Introduction
Taking the ‘unknown’ out of selective breeding
Selective breeding relies to some extent on ‘trial and error’—
hoping that the desired combination of favourable genes ends up
in some individuals, which can then be selected and interbred.
www.bbc.co.uk
Introduction
Two modern-day technologies that take care of the trial and error
nature of selective breeding are cloning and genetic engineering
(genetically modifying organisms).
technode.com
Genetic Engineering
Genetic engineering involves
adding a desirable gene to the
DNA of an individual or
removing and substituting a
gene and then ensuring that,
when it reproduces, it passes
this gene on with all of its other
genes, creating a transgenic
species.
www.earthtimes.org
Types of Cloning
Cloning involves the production of an individual that is genetically
identical to one that already exists.
There are three types of cloning:
someinterestingfacts.net
Types of Cloning
1. Reproductive cloning involves creating a genetically
identical, fully developed organism, using a cell (or a few cells) from
another mature organism. This whole organism cloning is a form of
asexual reproduction and so it is considered to be a reproductive
technology.
www.bioethics.ac.uk
Types of Cloning
Reproductive cloning is a technology used to generate an animal
that has the same nuclear DNA as another currently or previously
existing animal. Dolly was created by reproductive cloning
technology.
www.freewebs.com
Types of Cloning
In a process called "somatic cell nuclear transfer" (SCNT),
scientists transfer genetic material from the nucleus of a donor
adult cell to an egg whose nucleus, and thus its genetic material,
has been removed.
evolution.berkeley.edu
Types of Cloning
The reconstructed egg containing the DNA from a donor cell must
be treated with chemicals or electric current in order to stimulate
cell division. Once the cloned embryo reaches a suitable stage, it is
transferred to the uterus of a female host where it continues to
develop until birth
www.geneticsandsociety.org
Types of Cloning
Dolly or any other animal
created using nuclear transfer
technology is not truly an
identical clone of the donor
animal. Only the clone's
chromosomal or nuclear DNA is
the same as the donor. Some of
the clone's genetic materials
come from the mitochondria in
the cytoplasm of the enucleated
egg.
www.odec.ca
Types of Cloning
Dolly's success is truly remarkable
because it proved that the genetic
material from a specialized adult cell,
such as an udder cell programmed to
express only those genes needed by
udder cells, could be reprogrammed to
generate an entire new organism. Before
this demonstration, scientists believed
that once a cell became specialized as a
liver, heart, udder, bone, or any other
type of cell, the change was permanent
and other unneeded genes in the cell
would become inactive.
www.geneticsandsociety.org
Types of Cloning
2. Therapeutic cloning
involves using cells from an
individual to produce a cloned
early embryo, which is then
used as a source of embryonic
stem cells to replace
degenerating adult tissues or to
repair damage.
science.howstuffworks.com
Types of Cloning
The purpose of therapeutic cloning is not to produce a new
animal or plant, but to provide a source of cells that can be used
to repair adult tissue that has been damaged (e.g. by degenerative
disease).
www.arhp.org
Types of Cloning
Stem cells are important to
biomedical researchers because
they can be used to generate
virtually any type of specialized
cell in the human body. Stem
cells are extracted from the
egg after it has divided for 5
days.
cloningbasicsforkids.wordpress.com
Types of Cloning
The extraction process destroys
the embryo, which raises a
variety of ethical concerns.
Many researchers hope that one
day stem cells can be used to
serve as replacement cells to
treat heart disease, Alzheimer's,
cancer, and other diseases.
commons.wikimedia.org
Types of Cloning
3. Gene cloning occurs at a cellular level and involves
producing identical copies of a gene. It is an important step in the
process of genetic engineering.
www.abfrontier.com
Cloning—a contentious issue?
Cloning is not a new phenomenon— identical twins are naturally
produced genetic clones and occur in every animal species
studied for this phenomenon. Cloning is also common in
plants—botanists have been using cuttings, the splitting of bulbs
and other forms of asexual reproduction to propagate plants over
many centuries.
multiples.about.com
Cloning—a contentious issue?
Animals were first cloned a century ago when two-celled
embryos of sea urchins and salamanders were split. Bananas are
also clones of each other and vastly different from their ancestral
stock. They have a very limited gene pool.
firstivf.net
Cloning—a contentious issue?
Embryo-splitting leading to multiple births occurs naturally and
can be fairly easily replicated in a laboratory. However, cloning
from adult cells (of living or even deceased organisms) is not a
phenomenon that occurs in nature.
www.hoglezoo.org
Advantages of Cloning
Cloning is used as a form of selective breeding once an ‘ideal’
hybrid has been obtained.
 Cloning reduces the ‘unknown’ element in selective breeding—
the characteristics being bred can be precisely controlled.
This type of artificial selection occurs in growing seedless grapes
and bananas.
endtimeinfo.com
Disadvantage of Cloning
 If all members of a species are
identical, the population is less
likely to survive sudden
environmental changes and
would be vulnerable to foreign
pathogens.
If many clones are produced
from one parent organism, the
effect would be to reduce the
variability of the population as all
organisms would have identical
DNA.
www.immortalhumans.com
Natures Way
In nature, genes are conserved by
evolution only if they serve an
essential function for the
organism. For example, the genes
for cytochromes (proteins that are
essential for chemical respiration) are
conserved because, if they are
altered by mutation, the
individual cannot survive.
Therefore a mutation in such a
gene, which alters the protein,
will not be passed on.
evolution.berkeley.edu
Activity/Homework
-Students to complete DOT Point 5.1
a