Human Genetics and Medicine - BIOL 72 EXAM III -
April 14, 2011 NAME:
DO NOT USE ANY OTHER PAPER AT ANY TIME WITHOUT INSTRUCTOR PERMISSION
Part I: [46 points] Choose the one BEST answer. Circle
its letter. Read each question and all 5 choices carefully because
more than one answer might seem correct at first glance. 1.5
pt each
1. A locus is a
a. insect that eats crops
b. gene
c. allele
d. position on a chromosome
e. base pair
2. A gene determines an individual's potential to develop a
particular phenotype. This potential may be affected by
a. other genes
b. environment
c. evolution
d. a and b
e. all of the above
3. In humans, the dominance relationship between the IA and IB
alleles of the ABO blood group gene is an example of
a. complete dominance
b. codominance
c. incomplete dominance
d. epistasis
e. pleiotropy
4. The correlation between recombinant frequency and the
distance between genes can be used to construct a
a. linkage map
b. Punnett square
c. dihybrid cross
d. recombinant DNA
e. transcription
5. A genotype is incompletely penetrant if some
individuals do not express the expected
a. genotype
b. allele
c. phenotype
d. illness
e. disease
6. The process in which DNA is copied into messenger RNA is
called
a. reverse transcriptase
b. translocation
c. translation
d. transcription
e. transliteration
7. The stages of polymerization are (in order)
a. initiation, polymerization, termination
b. initiation, elongation, termination
c. elongation is the only step that is
always required; other processes may or may not occur
d. replication, transcription, translation
e. monomer, dimer, polymer
8. Incomplete penetrance can be observed
a. only in a population
b. in an individual whose genotype is known
c. only using biochemical analysis
d. a and b
e. all of the above
9. Which of the following does NOT correctly describe the
human genome?
a. ~ 46 miles of DNA in the haploid genome
b. 46 chromosomes
c. 22 pairs of homologous chromosomes + X +
Y
d. ~ 20,000 - 100,000 genes (depending on
who is counting)
e. 23 pairs of chromosomes
10. An SP/sp female that underwent one crossover event during
meiosis could produce which of the following gametes?
a. Sp and sP
b. SP and sp
c. Ss and Pp
d. a and b
e. all of the above
11. For the given DNA strand 5'-3' ATCGTCGATAGG the
corresponding 3'-5' RNA would be
a. GCACAGACTACC
b. TAGCAGCTATCC
c. UAGCAGCUAUCC
d. UAGCAGATAAGG
e. UAGCAGCTATCC
12. A man with a rare recessive disorder marries a woman who
is phenotypically normal. If the woman is homozygous at that
locus, the probability that their offspring will have the disorder
is
a. 0% because the disease is rare
b. 0% because the child will receive a
dominant allele from the mother
c. 100% because the child would receive the
trait from the father
d. 50%
e. 25%
13. A child of the parents described in #12 marries a heterozygote
at this locus. The probability that they will have a child with the
disorder is:
a. 0% because the disease is rare
b. 0% because the child will receive a
dominant allele from the mother
c. 100% because the child would receive the
trait from the father
d. 50%
e. 25%
14. The expected frequency of recombinant offspring from a
dihybrid testcross of 2 genes estimated to be 30 centiMorgans apart
is
a. 10 %
b. 20%
c. 30%
d. 40%
e. 50%
15. In the example above, the frequency of crossing over
during meiosis was probably about
a. 5 %
b. 15%
c. 30%
d. 45%
e. 60%
16. The example above
a. could only be seen in non-humans because
humans do not have recombinant offspring
b. could only be seen in non-humans because
humans do not do dihybrid crosses
c. could only be seen in
non-humans because humans do not do dihybrid crosses with enough
offspring to analyze in this way
d. is often observed in humans, for
example, when siblings look different
e. could only be
observed and analyzed in humans in small interbreeding populations,
e.g. on an isolated island
17. The two sugars found in nucleic acids are
a. uracil and thymine
b. glucose and fructose
c. deoxyribose and ribose
d. lactose and sucrose
e. glucose and sucrose
18. Copying a portion of DNA, but not all the DNA, is
a. replication
b. transcription
c. translation
d. not done in normal cells
e. duplication
19. Incomplete expressivity can be observed
a. only in a population
b. in an individual whose genotype is known
c. only using biochemical analysis
d. a and b
e. all of the above
20. The heterozygous phenotype being intermediate between that
of either homozygote illustrates
a. complete Dominance
b. co-dominance
c. lethality
d. incomplete dominance
e. all of the above
21. Haploid cells include
a. gametes
b. sperm
c. ova
d. a and b
e. all of the above
22. Which of the following best describes the general flow of
information?
a. DNA –> protein –> RNA
–>translation –> transcription
b. DNA –> transcription –> RNA –>
translation –> protein
c. RNA –> transcription –> DNA –>
translation –> protein
d. DNA –> transcription –> RNA –>
protein –> translation
e. RNA –> DNA –> protein –>
translation –> transcription
23. An environmentally caused phenotype that appears to be
inherited is called a (an)
a. pleiotropic gene
b. penetrant gene
c. expressed gene
d. phenocopy
e. dominant
24. Initiation is the first step in
a. translation
b. transcription
c. making a plastic polymer such as latex
d. a and b
e. all of the above
25. A nucleotide consists of
a. base + sugar + phosphate group
b. base + phosphate group
c. base + phosphate group
d. amines + sugars
e. Deoxyribonucleic acid
26. Given the gene sequence ABCDE, crossing over is expected
occur most frequently between
a. A – B
b. B – D
c. C – E
d. D – E
e. A – E
27. An allele that is expressed whenever it is present in a genome
is called
a. recessive
b. dominant
c. an example of the "doctrine of use and
disuse"
d. epigenesis
e. wild type
28. Characteristics of a normal human karyotype include
a. 23 chromosomes per haploid genome
b. 46 chromosomes per somatic cell
c. 24 different types of chromosomes
d. a and b
e. all of the above
29. Genetic variation results from
a. mutation
b. random segregation of chromosomes to
daughter cells during meiosis
c. crossing-over resulting in recombination
d. a and b
e. all of the above
30. The genetics of the human ABO blood types can be
used to illustrate
a. epistasis
b. codominance
c. incomplete dominance
d. a and b
e. all of the above
31. Some people with polydactyly have an extra toe;
others have an extra finger, illustrating a gene that
a. is incompletely penetrant
b. is variably expressed
c. has multiple alleles
d. is pleiotropic
e. this trait is really a phenocopy created
by surgeons
bonus: Write a question that you studied for, and forgetful me, I
neglected to ask. Answer your question. PLEASE ask
yourself something you can answer well! PLEASE answer the
question you actually ask. [up to 5 points awarded based on
question & answer]
Part II. 15 points each
1. a. Define linkage as it pertains to
genes, that is, what does it mean when we say that genes are linked
or not?
b. How do we determine whether or not genes
are linked?
c. Why is it true to say
that sometime linked genes (they really are linked) do not appear to
be linked. That is, when we try to observe them, they “behave”
as though they are not linked when really we know they are.
d. What would we need to do, in a case as
described in (c), to demonstrate that the genes really are
linked? 2. What information would you need to have, to answer
the following questions? What would be the likely answers, if
you knew that information? For example, if the question were
“Will Bill catch his early morning plane” your answer might be “need
to know if he has an alarm clock: he will catch the plane if he has
the clock set, and will not catch the plane if he
doesn’t”. Explain your answer.
a. the probability that a child will be Rh-
if the mother is Rh- and the father is Rh+
b. might Charlie be the
father of an A- (blood type, not grade) child if Charlie and the
mother are both O+? [She says he is, but he doesn’t want to pay
child support]
c. was there a
spontaneous mutation when a 5'1" mother and a 5'4" father had a 6'7"
basketball playing son? What else might explain it?
Part III. 24 pts Fill in the following table. Show
your work for possible partial credit; be sure that your work
is legible and labeled sufficiently clearly to be understood by
someone other than yourself. Be sure to list the genotypes
& phenotypes in a sensible order in the first column and put
only numbers in columns 2-4, so you use the table as a table.
genotypes AaBb x AaBb AB/ab x
Ab/aB Ab/aB b x Ab/aB
phenotypes