The exam has 100 possible points. There are 10 points per short answer/word
problem. This exam is due by December
17, 2015 at 9:15pm. You may turn it in
to the Biology Department office: Science Center 234, Montgomery
College-Rockville campus or turn it in to your instructor in person on December
17 from between 7:15pm-9:15pm.
have crossed true breeding purple peppers (AABB) with true breeding yellow
peppers (aabb). The resulting F1
progeny were all purple. When you
intercrossed two of the F1 plants, you got the following
results: 26 blue 46 purple 8 yellow. A
testcross of a F1 plant to a true-breeding yellow pepper resulted in
the following numbers of peppers of each genotype: 8 AaBb, 11 aaBb, 12 Aabb,
and 9 aabb.
(3 pts) Are the genes that control pepper color
linked? Perform a chi-square test to
(3 pts) Is the color of peppers due to a dihybrid
interaction where the double homozygous recessive phenotype is lethal? Perform a chi-square test to determine this.
(4 pts) Devise an alternative hypothesis for
inheritance of pepper color. Perform a
chi-square test to determine if your hypothesis should be rejected or not. If your hypothesis was rejected, continue to
devise other hypotheses until you have a hypothesis for inheritance that is not
rejected by your chi-square analysis.
and Bill have two male children. One of
their children has a genetic disorder that results in immune system deficiency,
while the other child has dwarfism.
Neither Bill nor Mary are affected by dwarfism, and neither of them have
immune system deficiency.
On Mary’s side of the family, her brother has immune system
deficiency. Also, Mary’s father, mother
and maternal grandmother do not have immune system deficiency, but Mary’s
maternal grandfather does. Additionally,
Mary’s mother has two brothers and one sister, and none of those siblings have
immune system deficiency. Mary’s
mother’s older sister has four children, 2 boys and 2 girls. One of these boys has immune system
deficiency but none of the other children do.
On Bill’s side of the family, Bill has a younger sister with
dwarfism and a younger brother that is not affected. Bill’s father was not affected by dwarfism,
but his mother does have dwarfism.
Bill’s mother has a younger brother who also has dwarfism and a younger
sister who does not. Finally, Bill’s
maternal grandfather had dwarfism, but Bill’s maternal grandmother did not.
points) Draw a pedigree for Mary’s family
point) What is the most likely explanation for the genetic inheritance of
immune system deficiency?
(3 points) Draw a pedigree for Bill’s family
point) What is the most likely explanation for the genetic inheritance of
points) If Bill and Mary have another child, what is the probability that this
child will have both immune system deficiency and dwarfism?
(2 points) If Bill and Mary’s third child does have
immune system deficiency and dwarfism, what is the probability that they have
that exact set of three children?
mice, genes for albinism (a), chronic inflammation (i), and reduced sense of
smell (r) are linked. You initially
crossed a mouse that is homozygous dominant for all three traits with a mouse
that is homozygous recessive for all three traits. You then crossed several of the resulting F1
offspring to mice that are homozygous recessive for all three traits. You observe the following phenotypes in the
colored, healthy, normal smell sense albino, chronically
inflamed, reduced smell sense colored, chronically inflamed, reduced smell
sense albino, healthy, normal smell sense colored, healthy, reduced smell sense
albino, chronically inflamed, normal smell sense colored, chronically inflamed,
normal smell sense albino, healthy, reduced smell sense
pts) Diagram a map between the genes and calculate the map distances.
pts) If the interference of these genes is 0.43, how many more F2
progeny will you need to observe to see at least 2 of each double recombinant?
pts) What are your expected numbers of each single crossover after you have
observed the total number of mice calculated in part (b)?
pts) If a fourth gene (z) exhibits 54% recombination with gene i, 35%
recombination with gene a and 51% recombination with gene r, will this gene be
on the same chromosome or a separate chromosome? If gene z is on the same chromosome as the
other three genes, indicate its location by copying and modifying your genetic
map from part (a).
how production of tryptophan is controlled in a bacterial cell.
the organization and function of the tryptophan operon. Describe what its default state is, and what
happens when tryptophan is present.
Include descriptions of the regulatory protein, the state of
transcription, and how that transcriptional state was achieved. (4 points)
what happens to the mRNA that is transcribed form the tryptophan operon when
tRNAs charged with tryptophan are present and when tRNAs charged with
tryptophan are are absent. Indicate which gene expression proteins or protein
complexes are involved. (3 points)
the processes in parts (a) and (b) occur in eukaryotes? Explain why or why not. (3 points)
and diagram transcription and RNA processing in eukaryotes. Indicate how these processes can results in 2
different mRNAs being produced from a single gene. Be specific about transcription initiation
and regulation, and be specific about what modifications are involved in RNA
processing and how they occur. (10 points)
humans, there are two primary types of colorblindness: red/green colorblindness
and blue/yellow colorblindness.
Red/green colorblindness is a sex-linked recessive trait and blue/yellow
colorblindness is a recessive autosomal trait.
Approximately 1 in 12 (8%) men and about 1 in 200 (0.5%) women are
affected by red/green colorblindness, while approximately 1 in 100,000 people
(0.001%) are affected by blue/yellow colorblindness. Fewer than 1 in 1 million
people (0.0001%) are affected by both red/green and blue/yellow colorblindness,
which results in the complete inability to see color, meaning they can only see
shades of grey.
Samuel (who is a red/green colorblind man) and Holly (a
homozygous normal woman) want to have children. Determine the possible
genotypes, phenotypes, and phenotypic frequencies (remember, gender is a
phenotype) for their children (2 points).
One of Samuel and Holly’s daughters is heterozygous for
the red/green colorblind allele and has children with a man who has normal
vision. What are the possible genotypes, phenotypes, and phenotypic frequencies
of their children? (2 points)
Nancy and Daniel have normal blue/yellow color vision,
but they have a child who is blue/yellow colorblind. What must be true about the genotypes of
Nancy and Daniel for this to be possible? (2 points)
Raphael (a blue/yellow colorblind, red/green normal
man) and Maria (a heterozygous blue/yellow, heterozygous red/green woman) want
to have children. What is the probability of Raphael and Maria having a
completely colorblind child? Will this child be male or female? (2 points)
What is the probability of Raphael and Maria having a
child with some form of colorblindness
(red/green, blue/yellow, or both)? (2 points)
humans, ABO blood type is controlled by a single gene with 2 codominant alleles
(IA and IB) and one recessive allele (i). The population of humans in the city of
Xanadu is 7568. 1874 of these people
have blood type O and 1243 of these people have homozygous blood type A.
(2 points) What are the frequencies of the IA,
IB, and i alleles assuming this population is randomly mating and
there is no significant mutation or natural selection?
(2 points) If a disease suddenly appears that kills 60%
of all people with type A blood, kills 40% of all people with type AB blood,
kills 10% of all people with type B blood, and kills 5% of all people with type
O blood, what is the relative fitness for each blood type?
(3 points) Using the relative fitness values you
calculated in part (b), determine what the allele frequencies of the IA,
IB and i alleles will be in the next generation.
(3 points) This same disease has affected a different
human population on the island of Atlantis.
This population is smaller and contains 1251 individuals. Of these, 398 are blood type O and 217 are
homozygous blood type B. This population
has been on the island for many generations, and therefore consists of
individuals that are related to each other by descent. The inbreeding coefficient in this island
population is 0.08. Assuming that the
disease kills the same proportions of people as in part (b), what will be the
frequencies of each blood type in this island population in the next
modifications to DNA sequences and resulting alterations in chromatin structure
can be analyzed by examining DNA methylation and histone modifications. To examine methylation of a DNA sequence, you
treat it with sodium bisulfite.
(2 points) If your original DNA sequence is:
ACAGTCCGTCGGAGCCTGCCAGTCGATCGCACCT and your sequence after treatment reads:
ACAGTTCGTCGGAGCTTGTTAGTCGATCGCACTT, which positions on the original DNA
sequence are methylated? (Indicate methylations with an * after the affected
(2 points) When this DNA sequence is replicated, which
of these methylations will be transferred to the new sequence? Indicate what the new sequence will be in the
standard 5’ ? 3’ direction.
(3 points) How does an increase in DNA methylation
affect chromatin structure and what does this do to gene expression? Be specific.
(3 points) Describe how chromatin structure is altered
in the process of X-inactivation and how the active X-chromosome prevents
itself from being inactivated. Include
the functions of Jpx, Xist, Tsix,
and describe what each of these gene products do. Be specific.
are investigating the heritability of tail length in cardinals (red
birds). To examine this, you have
analyzed tail length in many sets of parents and offspring. A table of this information is below. The following equations may be of use when
answering this question: H2 = VG/VP ; h2
= VA/VP ; h2 = b ; VP = VG + VE
+ VGE ; VG = VA + VI + VD
; R = h2 * S.
Tail length in Cardinals (measured in cm)
on this data set, what is the correlation coefficient for inheritance of tail
length? (2 points)
the correlation coefficient you calculated in part (a) strong or weak? Positive or negative? What does this tell you about the cause-and-effect
relationship between parental tail length and offspring tail length? (2
is the narrow-sense heritability of tail length? (2 points)
determining the heritability of tail length, you investigate the response to
selection. You determine that the
average tail length in the population is 5 cm and you select several birds with
longer tail lengths to mate. The average
tail length of the birds you selected is 7 cm.
What do you expect the average tail length of the offspring of these
birds to be? (2 points)
examine the effects of environmental factors on heritability of tail length,
you move several birds to a new location and examine their offspring over
several generations. You find that the
variance in tail length has increased due to the new environmental
conditions. What has this done to the narrow-sense
heritability of tail length? Explain. (2
Cheryl is a carrier of a Robertsonian translocation
between chromosomes 13 and 14. An
individual that has three copies of the genetic material on chromosome 13 will
be affected by Patau syndrome. Since
Cheryl is a carrier, she is normal and does not have Patau syndrome.
(3 points) If Cheryl wants to have children with
Stephen (a man who has a normal karyotype), what are the possible karyotypes in
their fertilized embryos? (Assume
chromosomes 1 through 12, chromosomes 15 through 22, and the X and/or Y
chromosomes are normal. You can express
your answer in numbers of chromosomes 13, 14, and the 13-14 translocation that
would appear in each zygote.)
(2 points) Zygotes that have three copies of the
genetic material on chromosome 14 are aborted and zygotes that exhibit monosomy
for either chromosome 14 or chromosome 13 are also aborted. If children born
with Patau syndrome typically die before the age of 3, what is the probability
that Cheryl and Stephen will have a daughter that lives until at least the age
(2 points) If the daughter from part (b) is a
translocation carrier like Cheryl, how many chromosomes does this daughter have
in each of his/her somatic cells?
(3 points) Cheryl and Stephen’s daughter becomes an
adult and attempts to have a child with Matthew. Matthew is heterozygous for a reciprocal
translocation between chromosomes 9 and 22, but otherwise has a normal karyotype. What is the probability that a viable zygote
will be made by fusion of the male and female gametes? What are the possible karyotypes for this
zygote? (Assume chromosomes 1 through 8, chromosomes 10 through 13, chromosomes
15 through 21, and the X and/or Y chromosomes are normal. You can express your answer in numbers of
chromosomes 13, 14, 9, 22, the 13-14 translocation, the 9-22 translocation, and
the 22-9 translocation that would appear in each zygote.)