Bio 4564/6564 Advanced Genetics Spring, 2023
Test I
Name__________________ Student ID:
_______________
Section 1 (30
pts.)
Unless stated otherwise
each question in this section is worth 2 pts. Please circle the letters that
precede the most appropriate answer(s) to the question asked. Circling more
than one letter in answering any given question will count against you.
1. Mendel’s 2nd law states that:
A. During gamete formation the segregation
of one gene pair is independent of all other gene pairs
B. Two members of a gene pair segregate from each other into
the gametes, whereby one half of the gametes carries one of the traits, the
other half carries the other
C. The union of one gamete from each parent
to form a resultant zygote is random with
respect to that particular characteristic.
D. Like
all things biological, genes come in pairs.
E.
When fertilization occurs, the
zygote gets one half of its chromosomal set from each parent, thus restoring
the pair.
2. Which of the following methods was not used by Mendel in his
study of the genetics of
garden peas?
A. maintenance
of “true-breeding” lines.
B. cross-pollination.
C. basic microscopy.
D. production
of hybrind plants.
E. quantitative
analysis
3. When a given trait is the
result of multigene action, one of the genes may mask the expression of one or all other genes. This phenomenon
is termed
A. epigenesis.
B. non-dysjunction.
C. overdominance
or heterosis.
D. epistasis.
E. incomplete
dysgenesis
4. Given that non-albino mice that lack the
dominant agouti allele at the B locus are black.
An agouti mouse that is
heterozygous at the agouti and albino loci (Aa
Bb) is mated to an albino mouse that is heterozygous at the agouti locus (aa Bb).
What percent of the progeny do you expect
to be agouti?
A. 0
B. 12.5
C. 37.5
D. 50
E. 100
5. What
percent of the progeny would you expect to be albino?
A. 0
B. 12.5
C. 37.5
D. 50
E. 100
6. “Recessive suppression” is an extension of
Mendelian genetics where:
A. each gene suppresses the other
B. recessive
suppression gives rise to a 15:1 ratio of one trait over the other when two
strains, heterozygous for each are mated.
C. a masking
of one of the phenotypes when the suppressor allele is suppressed
D. recessive
suppression gives rise to a 9:7 ratio of one trait over the other when two
strains, heterozygous for each are mated
E. recessive suppression gives rise to a 13:3 ratio of one trait over
the other when two strains, heterozygous for each are mated
F recessive
suppression is a condition when one of the alleles is lethal only when the
suppressor is present in the recessive state.
7. Which
of the following statements about Mendelian genetics need not be true?
A. Alternative
forms of genes are called alleles.
B. A locus is
a gene’s location on its chromosome.
C. Only two alleles can exist for a given gene.
D. A
genotype is a description of the alleles that represent an individual’s genes.
E. Individuals
with the same phenotype can have different genotypes.
8. Given
that, in dogs, the two traits of erect ears and large canines are due to
dominant alleles; and consequently -droopy ears and small canines are due to
recessive alleles. A dog homozygous dominant for both traits is mated to a
droopy-eared, small canine dog
If the two genes are
unlinked, the expected F1 phenotypic ratios should be
A. 9:3:3:1.
B. 1:1.
C. 16:0.
D. 1:2:1.
E. None of
the above
9. If NCO = 1 - (SCO +
DCO) then in yeast formation of haploids from meiosis:
A. NCO = 1 - 2(4NPD) + 0.5 x (T-2NPD)
B. NCO = 1 - (T-2PD) + 2(4PD)
C. m = 0.5 x (T-2NPD) + 2(4NPD)
D. NCO = 1 - (T-2NPD) +
2(4NPD)
E. NPD = 1 - (T-2PD) + 2(4PD)
D. m = T+ 8NPD
10. “B form DNA: is
said to be a right handed double
helix in which the bases are perpendicular to the helical axis, with ~11 base pairs per turn, contains
clearly defined major and minor grooves, C2'-endo pucker
preferred, and where the bases adopt an anti- configuration.”
Please
indicate (1) which part of the previous statement is NOT true by underlining
the phrase that is incorrect and then (2) choosing the appropriate (correct?) statement
below.
A. B form DNA is a right -handed helix.
B. B form DNA is a left handed helix.
C. B form DNA has a clearly defined major and
minor groove.
D. The
bases in B form DNA adopt an syn- configuration
E. There are ~10 bases per turn in B form DNA
F C3’-endo ring
pucker is preferred in B DNA
11. The
ABO blood groups in humans are determined by a multiple allelic system in which
IA and IB are codominant and are
dominant to iO.
If an infant girl born to a “type A” mother is found to be type AB, possible
genotypes for the father include
A. O or A only.
B. B or AB only
C. B only.
D. O, A, or B.
E. impossible
to determine.
12. A centiMorgan
defines:
A.
B.
the
number of cents in a genetic unit, the
“Morgan”
C.
the
genetic distance between one chiasmatic event and the next
D.
the number of chrossovers that occur between two gene pairs in 100
recombinant individuals
E.
the
distance between two gene pairs as it relates to the frequency of crossover
events occurring between them
F.
a
physical map unit that is less than a microMorgan,
but more than a milliMorgan
G.
13. One of the following describes a Type I
restriction enzyme. Please choose the
most appropriate description.
A.
B. A restriction-modification enzyme with three functionally distinct subunits
C.
A
restriction-modification enzyme with two subunits
C. An enzyme that binds and cuts DNA within a
palindromic DNA sequence
D. An
enzyme that binds and cuts DNA upstream of a palindromic DNA sequence
E.
An enzyme
that also methylates a DNA palindrome.
14. In discerning
the correct interpretation for phenotypic variations in the yeast asci if two
genes are unlinked then
A. the number
of tetratypes is equal to the number of double
crossover events
B. the number
of parental ditypes underestimates the number of recombinants
C. the number
of non parental ditypes equals the number of tetratypes
D. the number of parental ditypes equals
the number of tetratypes
E. the
number of non parental ditypes would normally approximate
half the outcomes.
F. the number of
parental ditypes will be greater than the number of non
parental ditypes
15. What genetic disorder is most likely
represented in the pattern of inheritance depicted in the family tree below?
A. Huntington’s disease,
B. Leigh syndrome,
C. Lichen sclerosis,
D. Red-green colour blindness,
E. Hairy Ears
Section 2
(55 pts.)
Please answer the following
questions using relatively short, concise
answers.
2.1. Please
read the following information and then answer the attendant questions below.
The allele b gives the Drosophila fly “small bristles” on the thorax and b+ gives large bristles (the
wild-type phenotype). The allele vg of a completely separate gene vg gives “vestigial wings”, while the wings
of a vg+ fly are normal. The allele cn of a third independent gene gives “cinnabar eyes”, and cn+ gives the normal red
eye. A female which is heterozygous for
these three genes is test-crossed, yielding one thousand progeny, that were classified
as follows.
67 vestigial winged flies, cinnabar,
5 wild-type for each locus
6 small bristles, vestigial wings
and cinnabar
385 cinnabar;
49 vestigial winged flies
69 small bristles
43 small bristles, cinnabar
380 small bristles, vestigial wings
(a) (5
pts.) What are the parental
chromosomes in the triple heterozygote?
A. b+
vg+ cn+ and b vg cn
B.
b+ vg+ cn and b vg cn+
C. b+ vg cn+
and b vg+ cn
D. b+ vg+ cn
and b vg+ cn+
E.
Do not
have enough information.
(b)
(5 pts.) What would be the gene
order that would account for the distribution of recombinants?
A.
b
vg cn
B. vg b cn
C. b cn vg
D. cn vg b
E.
Do not have enough information.
2.2a. (5 pts.)
Given that RF =? x (1-e-m) and that the empirically defined
recombination frequency between two genes = 9%, what is the value of the
“ultimate mapping unit”?
A. 1 – 0.55
B. 1 + 0.33
C. 0.67
D. 0.8
E 0.4
F 0.2
F 0.1
An example of an empirically
defined RF as being 0.09 (9.0%). Plugging
this value into the equation => 0.09
= 0.5 x (1 - e-m ) =>
e-m = 1 - 0.18 = 0.82, then to get a
value for "m" go to
the log table
|
m |
e-m |
|
0.000 |
1.000 |
|
0.100 |
0.905 |
|
0.200 |
0.819 |
|
0.300 |
0.741 |
|
0.400 |
0.670 |
|
0.500 |
0.607 |
|
0.600 |
0.549 |
|
0.700 |
0.497 |
|
0.800 |
0.450 |
|
0.900 |
0.407 |
|
1.000 |
0.368 |
2.2b. (4 pts.) Now,
calculate the more accurately determined recombination frequency in
centi Morgans?
The more accurately determined distance between two loci that do
experience crossing over (in cM or map units) = 50 x m cM. .......50 * 0.2 = 10 cM,
which is slightly greater
than the original value 9.0 cM(?), that was
empirically deduced.
2.3. (5 pts.) What does the term ”haplotype” mean? Give a brief explanation as to how it can be
used.
A
haplotype typically reflects a unique combination of SNP or MNP variants
that reside near each other on a chromosome.
To defne changes in DNA
sequence over evolutionary time Y
chromosome
2.4. (5 pts) Briefly explain
the phenomenon of “Recessive
suppression”
2.5. (5
pts.) Give two similarities
between a YAC and a bacterial plasmid and three differences
-giving a brief explanation
as to the importance of each of your choices
