name:_______________________
student ID:_____________________
Genetics L311 exam 3
November 11, 2016
Directions: Please read each question carefully. Answer questions as concisely as possible.
Excessively long answers, particularly if they include any inaccuracies, may result in deduction
of points. You may use the back of the pages as work sheets, but please write your answer in the
space allotted. However, you must show all your work. Clearly define your genetic symbols.
We will not make guesses as to what a particular symbol is intended to mean. Also, don’t assume
that strains are true-breeding unless this is stated in the question. Finally, show all your work.
Good luck.
page 2
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(20 points possible)
page 3
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(21 points possible)
page 4
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(26 points possible)
page 5
_______
(26 points possible)
page 6
_______
(7 points possible)
total
_______ (of 100 points possible)
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name:_______________________
student ID:_____________________
1. Short answers (2 points each, 20 points total)
A. The procedure whereby DNA is cut with a restriction endonuclease, separated by
agarose gel electrophoresis, transferred to membrane and incubated with a specific probe
is often referred to as a(n) Southern blotting .
B. A cell or individual with some deviation from a whole multiple of the haploid or
monoploid chromosome complement (eg. having one extra chromosome or missing one
chromosome) is said to be aneuploid .
C. An enzyme that binds a specific sequence of DNA and then cuts the DNA at that site
is called a(n) restriction endonuclease .
D. The ability of some bacteriophage to transfer any sufficiently small portion of
bacterial chromosome from one strain to another is generalized transduction .
E. The bacterial system that can be used either to produce a mutation in a specific gene or
to correct a mutation that is already present is called CRISPR/Cas9 .
F. In autopolyploidy the duplicate chromosome complement is composed of multiple
sets of chromosomes derived from a single species.
G. A(n) Robertsonian translocation is a special type of rearrangement in which the
long arms of two acrocentric chromosomes fuse.
Please provide concise definitions of the following terms:
H. episome: A DNA element that can be maintained independent of the host
chromosome.
I. reverse genetics: The general approach of creating a mutation in a specific, cloned
gene.
J. nucleoid: The general region in which prokaryotic DNA is found.
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name:_______________________
student ID:_____________________
2. In the rare South American flying lion tamarin, D. webbae, you observe two distinct
phenotypes: full mane and short mane. To study the transmission of this trait you perform
crosses that yield the results shown below.
full-maned female X short-maned male
All full mane
Cross siblings
All full mane
Cross siblings
full mane and short mane
A. Name and briefly describe the type of inheritance determining the type of mane in these
animals (6 points).
This looks like a maternal effect gene controls fur color. In maternal effect, the
mother’s genotype determines the offspring’s phenotype through factors deposited
in the egg either as RNA or protein.
B. What phenotypic ratio is observed in the F3 generations (4 points)?
3:1
3. You are studying the stinging sea anemone, O. nwosuae. You want to find out why these
creatures sting their neighbors relentlessly. You manage to isolate chromosomes from several
different populations of these animals and find that different populations have different forms of
chromosome 2 present. A. Determine the order in which the changes occurred and the name of
the rearrangement (8 points).
original
original
duplication
chromosome
strain III
strain I
pericentric inversion
strain II
deletion
strain II
strain I
paracentric inversion
strain III
strain IV
strain IV
B. Please diagram synapsis of chromosome 2 in an individual heterozygous for a strain II and a
strain III chromosome (3 points).
This is hard to draw on the computer. See your lecture notes, your UTA, the AI or me if
you have questions.
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name:_______________________
student ID:_____________________
4A. Your studies of magical talent in British Potter family leads to a remarkable discovery. You
find that a single gene, mgc, confers magical abilities. Miraculously you manage to purify the
MGC protein and obtain amino acid sequence of a portion of the protein. Name the strategy that
you will use and briefly (I just need the 3 or 4 key steps here) explain how you would go about
cloning the mgc gene (5 points)? This is cloning using degenerate primers. Prepare
degenerate primers based on the amino acid sequence. You would make a cDNA or
genomic library and perform a colony lift using the degenerate primers.
B. After cloning the mgc gene you want to know where it is expressed. You cannot easily
address this question in humans so you clone the mouse mgc gene. Explain how you would use
the mouse mgc gene to study where it is expressed in mouse. Include the relevant steps and
diagram the vector (5 points). You could fuse either the full length mgc gene or just its
promoter to a reporter such as gfp. Put your reporter transgene onto a retroviral vector
that includes neoR and transfect ES cells from a black mouse. Select for cells that receive
the transgene (verify by PCR). Introduce those cells into an embryo from a while mouse,
implant and wait for birth of chimeric mice. Chimeric mice are crossed with white mice.
Those that produce all black furred offspring are analyzed for presence of the mgc::gfp
transgene by pcr or Southern. Hets are crossed to establish a homozygous line.
C. You wish to study the function of mgc more fully by mutating the gene in mouse. Please
describe how you would go about producing mice homozygous mutant for the mgc gene. Please
include a diagram of any vector that you would use for this (5 points).
mgc 5’
neoR
mgc 3’
TK
1. Infect ES cells from black mouse using vector shown above. 2. Select for recombinants in
neomycin and ganciclovir. 3. Verify that recombinants had deletion within mgc by
Southern or PCR. 4. Mix engineered ES cells with embryo derived from white mouse. 5.
Implant into pseudopregnant mouse to produce chimeric mice. 6. Cross chimeric X white
to find those chimeric mice that produce all black offspring. Use Southern or PCR to ID
hets. 7. Cross hets to generate homozygotes.
D. While studying the magical world, you become interested in Hagrid and his extreme height.
Surprisingly you find that a single gene, that you named tall, accounts for much of his height.
You wish to clone the gene. You manage to show that it is tightly linked to hairy, a gene that
produces profuse hair growth. Please name and briefly describe the strategy (I just need the 3 or
4 key steps here) that you would use to clone tall (5 points). chromosome walk. Prepare a
genomic library and use colony lift with the hairy gene as a probe. Make a probe from the
end of the clone that you found and use that to re-screen the library. Repeat this until you
find tall. You need to have some way of recognizing when you’ve gotten the tall gene.
5. The production of transgenic crop plants, sometimes referred to as genetically modified plants,
is controversial in some parts of the world. Please list three potential benefits and three potential
concerns associated with their widespread cultivation (6 points).
Benefits include: better yield, better crop, reduced pesticide use, reduced herbicide use
Drawbacks include: spread of herbicide resistance, spread of pesticide resistance, possible
environmental damage, unknown human health risks including the possibility of allergic
response in some individuals
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name:_______________________
student ID:_____________________
6. While exploring an island off the coast of Costa Rica, you discover a dinosaur thought long
extinct, called Janardanasaurus rex, which you take home as a pet. After growing attached, you
decide to clone him. Assume you have access to all things you need to do this and that the
method discussed in class will work with dinosaurs.
A. Briefly explain how you would go about cloning this animal (5 points). Obtain an egg
suitable for Janardanasaurus development, ideally from Janardanasaurus. You would
remove the nucleus and introduce a nucleus from your pet, probably by fusing one of her
somatic cells with the enucleated egg. The egg then needs to be induced to develop and
incubated under conditions that permit the resulting embryo to develop (for a mammal this
would require implanting in a suitable host).
B. List four reasons why the clones won’t be exactly identical to your original pet dino (5
points).
The clone will be younger
Extranuclear genomes will differ
Random developmental events can’t be duplicated
The environment in which the clone lives will differ
C. You manage to make several clones of Janardanasaurus rex. Surprisingly a karyotype
analysis of your clones found some with unusual chromosome counts. J. rex normally has 40
pairs of chromosomes (i.e. 2n = 80). Fill in the blanks for each of the variants in the table below
(10 points):
ploidy of
# chromosomes
individual
81
trisomy
triploid
120
40
monoploid
tetraploid
160
monosomic
79
7. Imagine that you are counseling a couple who have just had a child born with Patau syndrome,
which results from trisomy 13. The couple’s first child was also affected by Patau syndrome.
When you examined the child’s karyotype you find 46 chromosomes.
A. How might you explain this result (4 points)?
The most likely explanation is that the child has a Robertsonian translocation involving
chromosome 13.
B. The couple wish to have another child. Which of the following provides the best estimate of
the probability that the couple’s next pregnancy will be affected by Patau syndrome (2 points)?
i. the couple’s next pregnancy is certain to be affected by Patau syndrome (probability = 1)
ii. the couple’s next pregnancy is certain not to be affected by Patau syndrome (probability = 0)
iii. the probability is the same as for the general population, which is ~1/25,000
iv. the probability is significantly higher than the general population risk
v. based on Mendelian principles, the probability is exactly 1/2
8. In an interrupted mating experiment, you obtain the data shown below for the time of entry.
5
name:_______________________
student ID:_____________________
Hfr1
gal
arg
thr
val
met
5 min
8 min
15 min
20 min
30 min
A. Show the genetic map for each of these genes on the circular chromosome. Indicate the
location of each origin and the direction of transfer (4 points).
5 gal
3
arg
hfr1
7
thr
5
val
10
met
B. Please describe briefly how you would identify the gal and arg wild-type recombinants that
you see in part A of this question (3 points).
After allowing conjugation to occur, cells would be plated on plates that lack gal and
include streptomycin and on plates that lack arginine and include streptomycin.
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