Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
MCDB 1041 Class 30
Learning Goals
•  Review transgenic animals, how they are made
and distinguished from a normal animal, and why
they are useful
•  Describe the methods of cloning, distinguishing
between reproductive and therapeutic cloning
•  Compare a clone to the organism it was cloned
from: how are they similar and different.
Final project: discussion of project and time for
brainstorming
18-1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Transgenic animals can make human protein
A recombinant piece
of DNA is made
The DNA is injected
into an oocyte
The rabbit produces
protein, and that
protein can be given
to humans
Used for treating Pompe disease, heart failure due to accumulation of glycogen
18-2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Once a transgenic animal is born and can start
producing milk, you can do a protein assay on the milk
to see if it contains protein of interest (in the case
shown, that would be alpha-glucosidase)
However, you’d probably like to know if you’ve been
successful BEFORE waiting for the animal to grow up.
What could you do as soon as the animal is born to
determine if it is transgenic?
18-3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
When scientists isolate DNA and observe it on a gel
(after PCR), they include a “control” lane
In this case, an appropriate control should show you
that your PCR reaction worked, whether or not the
animal is transgenic.
What can you use as a control?
18-4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
A transgenic animal only has one copy of the
inserted gene (not two copies, as for all its normal
genes) and thus has more of its own proteins than
the human protein that has been introduced
If you mate a transgenic animal to a normal animal,
what percentage of their offspring are likely to be
transgenic?
a.  They will all be transgenic
b.  75% will be transgenic
c.  50% will be transgenic
d.  25% will be transgenic
e.  0% will be transgenic
18-5
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Making a transgenic animal is a lot of work
If one could generate clones of an animal, it would
save having to breed them
What is a clone?
•  A clone is an organism derived directly
from the cell of another organism.
•  Nuclear content is identical
18-6
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Remember these transgenic animals?
A human disease model: Transgenic pigs
that have the human Altzheimer’s
disease-causing allele used to study
Altzheimer’s and potential treatments
(cloned in 2007)
Human drugs: These clones were
made from a transgenic goat that
produces recombinant human
antithrombin III (rhAT) in their
milk. This protein prevents blood
from clotting.
(cloned in 1999)
18-7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Dolly, the first mammal cloned from an adult, somatic cell
18-8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
How to Clone an animal
Two basic techniques:
1. Embryo splitting (twinning)
Separate the two
cells from each
other
Each cell develops
into a complete
embryo
2. Nuclear fusion or injection
18-9
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nuclear injection technique
18-10
Egg and its surrounding
cells are removed
from the ovary
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Egg and its surrounding
cells are removed
from the ovary
Somatic cells to be cloned are separated
Nucleus of egg removed
by microsurgery.
18-11
Nucleus of cell removed
by microsurgery
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Egg and its surrounding
cells are removed
from the ovary
Cells separated
Enucleated egg
Nucleus removed
by microsurgery
Nucleus injected
into egg
18-12
Stimulate the egg
to fool it into
thinking it’s been
fertilized
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Egg and its surrounding
cells are removed
from the ovary
Cells separated
Nucleus removed
by microsurgery.
Nucleus removed
by microsurgery
Nucleus injected
into egg
Egg implanted into
surrogate mother
18-13
Twenty-one days later,
a cloned mouse is born.
Stimulate the egg
to fool it into
thinking it’s been
fertilized
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Are clones truly identical?
Dolly
Dolly and Bonnie
How are they different?
CC
(Copy Cat)
18-14
Rainbow
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Telomeres: regions of DNA at the end of chromosomes
These ends shorten every time the chromosomes replicate
A cell from a mature animal
will have shorter telomeres
than a cell from an embryo.
Take that cell and develop a
clone from it.
When clone is born, its
telomeres will be even
shorter!
18-15
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Mitochondria
A clone will contain mitochondria from:
a.  The egg that the nucleus came from (donor)
b.  The egg that the nucleus is transplanted into (host)
c.  Both the host egg and the donor egg
d.  Its own nucleus
18-16
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Notice that
Rainbow and her clone,
CC look very similar but
not identical
Rainbow
CC
CC is a clone of Rainbow
Why do they look different?
a.  Uterine environment differences impact hair color
pattern
b.  Different coat color alleles are active in different cells
in each cat
c.  One of them is heterozygous for the coat color gene;
the other is homozygous
d.  The expression of the coat color alleles is masked by
another gene
18-17
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
X inactivation occurs in an early stage XX embryo
•  One X chromosome is inactivated in every cell
So in fact, XX individuals have 2 X chromosomes but
only use one of them
•  Because black (XB) and orange (Xb) coat color is
determined by a gene on the X chromosome, a
heterozygous animal, XbXB will have patches of
orange and patches of black
•  Since X inactivation is random, the clone will not
have the same patches
(the white coat color is determined by an autosomal
gene)
18-18
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Why Clone?
Reproductive vs. Therapeutic Cloning
These techniques begin the same way: isolate genetic material
from a cell and replace the nucleus of an egg with this genetic
material
Reproductive Cloning
•  Grow a clone of an animal or human up to adulthood
•  Currently banned for humans in the US and Europe
Therapeutic Cloning: shows a lot of promise, but not in active use
•  Insert nuclear material from an individual human cell into an egg
•  Let egg grow to 8 cells, then culture the cells
•  The cells are now stem cells, and can be put back
into same person
18-19
Gene Therapy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Final projects: presented in the last week of class
1.  Determine a socially relevant goal for genetic
engineering/biotechnology
2.  Give a historical perspective on the goal you’ve
chosen.
3.  Identify a gene or genes of interest that might be
used to address your above goal
4.  Determine how you could manipulate this gene, and
where to express the gene(s) of interest to achieve
your goal.
Ideally, no more than 4 people in a group. See me if you have lost
a group member and no longer have two groups at your table.
The project is worth 50 points total: 40 for your group powerpoint
presentation, and an additional 10 for an individually written summary
18-20
of
your project
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Examples:
•  Get rid of wrinkles: engineer a collagen gene to be
easily taken up when applied to the skin, determine a
way to get the gene to be translated into collagen
protein once on the skin, put this into skin cream
•  Control fruit ripening: Engineer strawberries to
reactivate a gene that they do not normally express
but which is present in their genome. When activated
(by an increase in temperature, for example), the fruit
could be induced to ripen. Thus, strawberries could be
picked before they are ripe and then induced to ripen
after transport.
18-21
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
To develop and choose a project:
Right now: brainstorm with your group on
some ideas; feel free to use your
computers to look things up
Make a list of these ideas and turn them
into me before you leave. If you have
a favorite idea, or have already
decided on your topic, please indicate
this!
18-22