Bio 4564/6564 Advanced Genetics Spring, 2023
Name__________________ Student ID: _______________
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
A. maintenance of “true-breeding” lines.
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
C. overdominance or heterosis.
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?
5. What percent of the progeny would you expect to be albino?
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
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:
<![if !supportLists]>B. <![endif]>the number of cents in a genetic unit, the “Morgan”
<![if !supportLists]>C. <![endif]>the genetic distance between one chiasmatic event and the next
<![if !supportLists]>D. <![endif]>the number of chrossovers that occur between two gene pairs in 100 recombinant individuals
<![if !supportLists]>E. <![endif]>the distance between two gene pairs as it relates to the frequency of crossover events occurring between them
<![if !supportLists]>F. <![endif]>a physical map unit that is less than a microMorgan, but more than a milliMorgan
13. One of the following describes a Type I restriction enzyme. Please choose the most appropriate description.
<![if !supportLists]>A. <![endif]>
<![if !supportLists]>B. <![endif]>A restriction-modification enzyme with three functionally distinct subunits
<![if !supportLists]>C. <![endif]>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
<![if !supportLists]>E. <![endif]>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
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
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+
<![if !supportLists]>E. <![endif]>Do not have enough information.
(b) (5 pts.) What would be the gene order that would account for the distribution of recombinants?
<![if !supportLists]>A. <![endif]>b vg cn
B. vg b cn
C. b cn vg
D. cn vg b
<![if !supportLists]>E. <![endif]> 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
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
2.2b. (4 pts.) Now, calculate the more accurately determined recombination frequency in
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
Circular when not restricted…
Single origin of replication
Antibiotic resistance gene
Presence of centromere
Presence of telomeres
Presence of ARS or Yeast origin or replication.
2.6. (10 pts.) Explain what Z- DNA is and give a “specific” example of what might cause it,
what are the consequences (in your example) and where it might be found.
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2.7. (5 pts.) Briefly explain the phenomenon of “ring pucker” and how it might affect DNA structure.
_______________C2’ endo = B-form DNA ______________________________________________
_______________C3’ endo = A-form DNA ______________________________________________
_______________C2’ endo, C3’ endo = Z-form DNA ___________________________________________
2.8. 6 pts.) List FOUR discrete proteins or protein complexes that may be found in or around the DNA
replication fork of a EUKARYOTIC cell, and briefly explain their role(s) in DNA replication.
Be sure to mention whether they affect “leading strand” replication “lagging strand” replication or both.
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