ALE #7
Ch.11 & 12: Gene Regulation & DNA technology
Name__________________________________________
1. Please define the following important players in eukaryotic gene regulation:
a. transcription factors – regulatory proteins that help RNA polymerase bind to the
promoter. Thus they promote transcription.
b. Activators - regulatory proteins that bind to enhancer sequences, interacting with
transcription factors to promote transcription.
c. Silencers - regulatory proteins that inhibit transcription.
d. Promoters – a section of DNA that indicates the start of a gene. When RNA
polymerase binds to a promoter, transcription occurs
e. Enhancers – these are sections of DNA that play a role in the regulation of gene
expression. When activator proteins bind to enhancers, they assist other
transcription factors to bind to RNA polymerase. This helps to promote
transcription
2. Please describe how each of the following processes exerts control over eukaryotic
gene expression:
a. DNA packing –during prophase of mitosis and meiosis, chromatin becomes tightly
packed by wrapping itself around histone protein and coiling into tight helical fibers and
supercoils. In this highly packaged state, transcription is nearly impossible. RNA
polymerase will be blocked from binding to promoters
b. X chromosome inactivation – early in embryonic development of female mammals,
one of the two X chromosomes in each cell becomes highly compacted and
(permanently?) inactive, preventing transcription of genes on the inactive X chromosome.
c. alternative RNA splicing – removal of some exon (coding) material along with the
non-coding introns can result in the production of different kinds of proteins from one
gene.
d. RNA interference – small, complementary RNA strands bind to mRNA transcripts,
thus blocking the translation of a gene.
3. Read the short article attached from AICR (American Institute for Cancer Research)
Science Now titled Epigenetics: A New Frontier in Cancer Research from the Spring
2007 Issue then answer a-c below
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a. What are the two most widely known epigenetic processes?
1.DNA methylation – adding methyl groups to DNA to turn genes on or off without
mutating the gene itself.
2. Histone modification – loosens the DNA coils to enhance transcription of genes.
b. How does lunasin kill cancer cells?
It modifies histones in cancers cells, and this prevents DNA coil unwinding. This has the
effect of killing the cancerous cell.
c. How did the four nutrients given to pregnant agouti mice change their babies
chance of obesity, cancer and diabetes?
The nutrients cause methyl groups to attach to the agouti gene, thereby silencing it
(turning off transcription). This had the effect of changing fur coat color and
decreasing appetite.
4. What is the difference between reproductive cloning and therapeutic cloning?
Reproductive cloning involves implanting a cloned embryo into a surrogate mother for
the purpose of creating an entire new organism. The purpose of this would be to create
domestic animals with desired traits or to reintroduce extinct or endangered organisms.
Therapeutic cloning involves the creation on an embryo clone in culture in order to
induce the stem cells to create new tissues or organs, etc for the individual from which
DNA was derived. This could be used to cure many diseases and to fix damaged body
parts, without having to grow an entire new organism just for harvest.
5. In the table below, list the pros and cons of cloning. Be prepared to share these in
class.
Pros
Cons
 Agriculture: produce livestock or
 Clones are not really clones!
crops with desirable traits,
Epigenetics tells us that even
potentially decreasing the need for
though the genes of two organisms
antibiotics, herbicides, pesticides,
might be the same, that does not
increasing crop yield, etc.
mean their gene expression will be
the same.
 Medicine: create animals that
would secrete certain desired
 In fact, we see that many cloned
proteins in their milk
animals have reduced viability.
 Increasing the population of a rare
 Cloning reduces genetic variability,
or endangered plant or animal
which many reduce the
population’s ability to adapt to its
 Therapeutic cloning has the
environment
potential to cure almost any disease,
and to eliminate the need for organ
 Disadvantages of therapeutic
donation. Patients could be given
cloning? For humans, some people
stem cell transplants without any
will always object to the use of
chance of rejection.
human embryos for scientific
research (controversial). However,
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if scientists are trying to induce
other kinds of stem cells (cord
blood, bone marrow) to grow into
various tissues.
6. List the pros and cons of genetically modified (transgenic) organisms in the table
below. Be prepared to share these in class.
Pros
Cons
 Plants: create plants that are
 Plants: transgenes can be
resistant to bugs or disease, thus
transferred into the environment
reducing the need for herbicides
and hybridize with native plants.
and pesticides
This could create invasive weeds,
which are extremely harmful to our
 Improved nutritional quality of
environment and economy
crops can save millions of
malnourished people worldwide.
 Once the transgenes have
“escaped”, there is not way to get
 Improved water use efficiency and
them back.
nitrogen use efficiency can reduce
our environmental (and carbon!)
 Could introduce new allergens into
footprint on the earth.
nature or our food supply.
 Animals: Easy creation and harvest

of pharmaceuticals – especially
beneficial would be the production
of human proteins needed for
medicine (insulin).
 Creation of domestic
animals/livestock with superior
traits, reducing the need for
antibiotics, etc.
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