Download Genetics 314 – Spring, 2005

Name:__________________________________
Genetics 314 Spring, 2007
Final Exam – 150 points
1. You have been asked to assist in organizing a DNA sample library for the local public
school district. The problem is that they are short of funds and the previous person
forgot to label the samples as to DNA source (virus, bacteria or eukaryote). They ask
if you could separate the samples just by heating and cooling the samples.
a) Could you generate this data just by heating and cooling the samples?
b) Would heating the samples help in determining the general DNA sources? Why or
why not?
c) After heating the samples would letting them cool help you separate the samples
into their various sources (virus, bacteria or eukaryotic)? What would you look for
and how could you differentiate virus DNA, bacterial DNA, and eukaryotic DNA?
2. You are given a DNA sequence for a nine amino acid polypeptide. The DNA
sequence is shown below:
3’ TAC GAC AAA CCG CCA TTC TGC GCT CAT ATT 5’
a) What would be the mRNA sequence based off this DNA sequence?
b) Based off your mRNA sequence what is the amino acid sequence.
c) If there are nine amino acids why are there 10 codons?
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3. You want to express the DNA sequence in bacteria. Your friend says you need to add
additional sequences to get expression. What sequences do you need to add and what
are they needed for to allow expression of the DNA sequence in bacteria?
4. You are told that it is possible to make antibiotics that can target bacteria in your body
to halt transcription and/or translation without interfering with these processes in your
own cells. What makes this possible?
5. You would like to regulate expression of a gene inserted into bacteria. What are the
two general types of gene regulation in bacteria and which would be best if you wanted
to keep a constant level of expression of your gene? Briefly explain your answer.
6. You become interested in gene regulation and you discover that gene regulation differs
between prokaryotes and eukaryotes. What extra step is required in eukaryotes for
gene expression that allows for a form of gene regulation that is unique to eukaryotes?
Describe one form of regulation in eukaryotes that is related to this extra step.
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Name:__________________________________
7. You are hired to work in the Agricultural Biotechnology facility on campus and find
you are in a lab that works with mutagens. You observe that one set of researchers
work with mutagens that induce missense mutations while another group works with
mutagens that induce frameshift mutations. What is the difference in the two types of
mutagens and which one would have the greater potential to produce a non-functional
gene product? Briefly explain your answer.
8. You are asked to assist in the lab that is studying viral genetics. Your first job is to
determine if recombination can occur between virus.
a) What is required for viral recombination to occur?
b) Give one example of how viral recombination could occur?
c) extra credit – Why is this topic of such interest in the media throughout the world at
the moment?
9. You are transferred to the gene evaluation lab and you are assigned the responsibility
to move candidate genes into bacteria to test their expression. What are the forms of
bacterial recombination that are at your disposal to move the genes into bacteria and
which would be the easiest to use? Briefly explain your answer.
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Name:__________________________________
10. What are the three main differences between meiosis and mitosis that relate to genetic
recombination in eukaryotes?
11. You are studying a trait that is not following normal inheritance patterns. Some
generations the gene is expressed and in other generations it is not expressed. It does
not seem to be related to which parent donates the gene to the progeny and as time goes
on additional genes for other traits appear to be being turned off and on as the
generations’ progress. What could be causing this variation in expression and briefly
explain what is happening.
12. You have an allohexaploid with 72 chromosomes
a) What is the 2N somatic chromosome number?
b) What is the N gametic chromosome number?
c) What is the X monoploid chromosome number?
d) What can you say about the origin of the chromosome sets in this species?
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Name:__________________________________
13. You overhear an argument between a plant geneticist and an animal geneticist. A
new chemical has come on the market that can disrupt mitotic divisions in gametes
after meiosis. The plant geneticist is concerned about the chemical’s impact on the
world’s food supply but the animal geneticist feels the chemical will have little
impact on producing animals for food. Why the difference in concern? Briefly
explain your answer.
14. You are studying a genetic disorder in humans and discover that there are two
possible ways for the disorder to occur; trisomic for chromosome 16 or a
translocation involving chromosome 16.
a) How is it possible for both conditions to result in the same genetic disorder?
b) If a couple produced a child with the disorder due to the translocation of chromosome
16, what would be the potential for the couple’s next child to have the same disorder?
Briefly explain your answer.
15. What are Mendel’s two laws and how do they relate to chromosome behavior in
meiosis?
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16. You are studying a trait and observe an odd expression in the females. There appears
to be a random expression of a trait with parts of the animal showing one allele and
other parts of the animal showing expression of the other allele. You never see this
type of expression in males. A friend says it could be explained if the gene was on
the sex chromosomes. Could this be the answer and if so, how would it explain the
expression observed in the females and males for this trait?
17. You are studying two mutant plants that are much shorter than the normal plants and
you wonder if the mutations are in the same gene or different genes that affect height.
a) What cross would you make to determine if the mutations are in the same gene or
different genes?
b) What would you expect to observe in the progeny for height if:
1) The mutations were in the same gene
2) The mutations were in different genes?
17. You are studying traits that appear to be under the control of two genes but the ratios
you recover are odd.
a) The first ratio is not the expected 9:3:3:1 but instead is a 9:6:1. How is this possible
and what is this modified ratio due to?
b) The second ratio is a 15:1 instead of a 9:3:3:1 ration. Again, how is such a ratio
possible and what is the modified ratio due to?
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18. Molecular markers are being viewed as a critical tool in the area of proactive
medicine where genetic disorders are diagnosed before they occur and preventative
measures can be taken to mitigate the health issues associated with the genetic
disorder. Key to the success of such an approach is having a molecular marker
system that is highly accurate.
a) What aspect of genetic linkage can be used to improve the accuracy of molecular
markers for diagnosing the presence of a gene for a genetic disorder?
b) Give an example on how such a system would reduce the probability of a
misdiagnosis.
19. What is the difference between a trait being under quantitative genetic control and a
trait under qualitative genetic control?
20. What two factors control the heritability (h2) of a trait? How does this influence the
rate of genetic gain you can expect when doing selection for improving a trait?
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Name:__________________________________
21. There are four evolutionary forces that can keep a population out of Hardy-Weinberg
equilibrium. What are they and which one do you feel has the greatest effect on
speciation? Briefly explain your answer.
20. What conditions are needed for speciation to occur?
21. You find two flowering plants that phenotypically appear to be closely related. You
cross them and recover viable F1 progeny. When you try to cross the F1 plants you
discover they are sterile. You look at the meiotic cells in the flowers and observe
several rings of 4 at metaphase I and two dicentric bridges when the homologous
chromosomes attempt to separate at anaphase I.
a) What is causing the abnormal chromosome pairing and separation in the F1 plants?
b) Could this be the reason for the sterility that you have observed in the F1 generation?
Briefly explain your answer.
c) Would these two flowering plants be considered different species and if so what type
of isolation is being demonstrated that justifies the species designation?
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Name:__________________________________
Extra Credit – 15 points
1. For the following evolutionary forces what are the two factors that affect the level of
impact the force has on changing the allelic frequencies:
a) migration
b) genetic drift
2. What are the three types of selection and how does each change a population (can use
graphs)?
3. What is meant by the term genetic load and is it good or bad to be considered a
genetic load on a population?
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