Download 5 POINT QUESTIONS 1. A. Give the anticodon sequences (with 5` 3

5 POINT QUESTIONS
1.
A. Give the anticodon sequences (with 5' 3' direction being indicated) of all possible Aspartic Acid
(Asp) tRNAs.
3’ CUA 5’ AND 3’ CUG 5’
B. Give the anticodon sequences of a minimum set of Aspartic Acid (Asp) tRNAs.
3’ CUU 5’
2.
For a UUU Phenylalanine (Phe) codon, how many of the transversion base pair substitution
mutations would be in each category below?
Silent
3.
__0___
Missense
__6___
Nonsense
___0__
Briefly describe the structure of the primary DNA lesion produced by exposure to ultravioltet (UV)
light.
Two adjacent thymines in the same strand are crosslinked by two covalent bonds to produce a
“cyclobutane pyrimidine dimer”.
See diagram in Fig. 18.15.
4.
A. Identify the primary DNA lesion that results from the deamination of Cytosine.
A GU m mismatch.
B. Identify the primary DNA lesion that results from the deamination of 5-Methyl Cytosine?
A GT mismatch.
5.
What is a "two-way" mutagen?
Two way mutagens are capable of inducing several types of mutation that will reverse each
other’s effects.
i.e. BOTH AT - GC AND GC - AT.
6.
Give one specific example each of
constitutive heterochromatin: centromeres; Y chromosomes of Drosophila and humans
facultative heterochromatin: Barr Bodies (inactive X chromosomes); mentioning Bar Eye in
Drosophila or "position effect variegation"
7.
8.
For each human karyotype shown below state the biological gender and the # of Barr bodies.
Karyotype
Gender
# Barr Bodies
XYY
MALE
0
XXY
MALE
1
XXXX
FEMALE
3
Describe the molecular structure of a nucleosome.
A nucleosome consistes of about 2 turns of double helix wound around a core consisting of 2
molecules of each histones H2A, H2B, H3 and H4. One molecule of histone H1 attaches outside
the core.
See text Fig. 12.5.
9.
In a certain eukaryotic species, the DNA sequence found at the right-hand ends of chromosomal
DNAs is:
- - - A T A G G C G A T A G G C G A T A 3'
- - - T A T C C G C 5'
Predict (below) the sequence of the telomerase-associated RNA:
5' - U A U C G C C U A U - 3'
10.
Which two of the processes of bacterial gene transfer would NOT be inhibited by the presence of
DNA degrading enzymes (DNases) in the exterior environment?
1: CONJUGATION
2: TRANSDUCTION
11.
The diagram shows the genetic map of a bacterial
genome with the locations of genes A, B, and C
indicated.
B
C
Bacteriophage X can transduce any of the 3 genes to
recipient cell.
a
Bacteriophage Y can transduce only gene A to a
recipient cell.
Explain fully the basis for the difference between
bacteriophage X and Y.
A
Bacteriophage Y carries out GENERALIZED TRANSDUCTION.
Bacteriophage X is a temeperate phage and carries out SPECIALIZED transduction. Its
chromosomal insertion site is near genes B and C.
12.
An F+ E. coli cell is not able to transfer bacterial genes to a recipient by conjugation. Describe
what must happen in an F+ cell to convert it to an Hfr strain that would be capable of
transferring bacterial genes.
The F DNA must undergo homologous recombination with a complementary sequence (IS
element or transposon) in the chromosome so that the 2 DNA molecules fuse.
13.
The DNA sequences recognized by regulatory proteins such as the Lac Repressor protein often
share a certain feature with the DNA sequences recognized by restriction enzymes. What common
feature do they share, and why is this the case?
The sequences are often inverted repeats because the proteins that bind to them are dimers
of 2 identical subunits that are oriented in opposite directions.
14.
Assume that there is a single base pair mismatch (SNP) between a 40 base nucleotide hybridization
probe and its complementary target DNA sequence. What factor will primarily determine the
thermal stability of the hybrid between the probe and its complementary sequence?
The position of the mismatch along the length of the double-stranded hybrid ("effective
length") determines the thermal stability.
15.
A. InDel polymorphisms are detected by two different molecular methods. What are they?
1. ASO hybridization
2. PCR of the InDel region followed by gel electrophoresis
B. What factor determines which of these two methods of detection (above) would be
appropriate for a given InDel?
Length or size of the InDel. Smaller InDels (1-2 bp) are detected by ASO hybridization. Larger
InDels are detected by PCR amplification of the InDel region followed by gel electrophoresis.
10 POINT QUESTIONS
1.
A woman is born with Turner Syndrome (an aneuploid condition) and red-green color blindness;
associated with expression of an X-linked allele. Both her parents had normal vision.
Explain as fully as possible.
The woman inherited the X-linked recessive allele from her mother, who was heterozygous for
the normal allele.
The father’s sperm did not contain either an X or a Y chromosome as the result of meiotic
non-disjunction. It is not possible to determine whether the non-disjunction occurred at the
first or second meiotic division.
2.
The genomes of three species D, E, and F all have the same basic number of chromosomes, x=7.
These genomes were originally derived from an ancestral plant species, and they diverged from
each other sufficiently long ago so that the chromosomes from one genome no longer pair with
chromosomes from the other species at meisosis. For plants with the following chromosome
complements state (a.) the number of chromosomes, (b.) the appropriate term to describe the
plant's genetic makeup, (c.) whether or not the plant is likely to be fertile, and (d.) the #
chromosomes in the gametes.
Genotype
EEE
DEF
FFFF
DD FF
DD E FF
a.
# Chromosomes
21
21
28
28
35
b.
autotriploid
allotriploid
autotetraploid
allotetraploid
allopentaploid
c.
Fertile?
NO
NO
FERTILE
FERTILE
NO
b.
# Gametic
Chromosomes
14
14
3.
A. For each of the 2 diploid genotypes below for the Lac Operon, determine whether the gene
products will be made in the presence of and absence of, the inducer (lactose). Give your answers
by filling in the 4 boxes with "+" or "-" (See example.)
B. Give the overall cell phenotype. The possibilities would include
Wild-type (Lac+ regulated = Lac+ inducible)
Lac+ unregulated (constitutive)
LacEXAMPLE:
GENOTYPE
I+ P+ O + Z + Y+
I+ P+ O + Z + Y+
No Inducer
I- P+ O + Z + Y+
Inducer
Present
No Inducer
Inducer
Present
DIPLOID
GENOTYPE
I- P+ O + Z + Y+
I- P+ O c Z + Y-
Permease
[LacY]
-
-
Cell Phenotype
Wild-Type
DIPLOID
GENOTYPE
I- P+ O + Z - Y-
b-Galactosidase
[LacZ]
No Inducer
Inducer
Present
+
+
b-Galactosidase
[LacZ]
Permease
[LacY]
+
+
+
+
b-Galactosidase
[LacZ]
Permease
[LacY]
+
+
+
+
Cell Phenotype
Lac+
unregulated
(constitutive)
Cell Phenotype
Lac+
unregulated
(constitutive)
4.
The genome of the bacterial virus Lambda is 50 kilobases of linear double-stranded DNA.
The overall base composition is 50%GC:50% AT.
Predict the number and the size of restriction fragments obtained by digestion of Lambda DNA
with the restriction enzyme BssHI (5' GCGCGC 3').
A. SIZE of fragments = 46 = 4,096 base pairs
B. NUMBER of fragments = 50kb / 4.096 kb = 12 fragments
C. You isolate the double-stranded DNA genome of a different, unrelated bacterial virus that is
also 50 kb in length. When you digest this DNA with BssHI you several times more restriction
fragments, with much smaller sizes, than you get from Lambda DNA. Propose a simple explanation
for why 2 genomic DNAs of the same size would give very different numbers of fragments when
they are cut with the same restriction enzyme.
CREDIT FOR EITHER ANSWER:
The base composition of the second viral genome is lower %GC.
Some potential BssHI restriction sites in the Lambda DNA were blocked by methylation.
5.
A particular PCR reaction uses the 3 temperatures listed in Column A in the cycle.
The temperatures are not necessarily given in the correct order. In Column B, number the steps 1,
2, and 3 in their proper sequence assuming that you have just mixed the reaction components
together and started the thermocycler.
In Column C, indicate what is actually happening in the reaction at each temperature by using the
appropriate choice from Column D.
A
Cycle
Temperature
55 °C
B
Sequence #
C
D
Choices for Column C
2
b.
72 °C
3
c.
95 °C
1
a.
a. Denaturation (separation) of
double-stranded
template DNA
b. Hybridization of primers
with complementary
sequences in the
template DNA
c. Synthesis of DNA by Taq
polymerase
6.
The diagram below is a restriction map of a gene containing 2 introns.
The vertical arrows indicate the location of restriction enzyme cut sites for a certain restriction
enzyme. The number give the distance between the cut site in nucleotide base pairs.
220
120
115
110
80
200
160
130
The dark horizontal arrows show the binding sites for 2 PCR primers used to amplify a portion of
the gene.
A. Predict the size of the PCR product in kb. __________800 kb__________kb
B. The PCR product is digested with the restriction enzyme whose cut sites are shown, and the
fragments are separated by agarose gel electrophoresis. Sketch in the appropriate # of DNA
bands you expect to see, in the appropriate locations in the gel, relative to the MW size
standards.
C. You transfer the restriction fragments from the gel to a membrane and perform a Southern Blot. The
hybridization probe is a synthetic oligonucleotide whose sequence determined by "reverse
translation" of the first 20 amino acids in the protein sequence. Label the bands that would
contain DNA sequences that would hybridize with this probe.
250
200
200
160
150
130
120
100
100
110
80
Label
7.
Transformation
C.
A.
Conjugation
H.
B.
Telomerase
E.
C.
GATC
J.
D.
Intercalating
Agent
D.
E.
Minisatellite
I.
F.
300 Angstrom
Fiber
B.
G.
Wobble
A.
H.
Operator
K.
I.
cAMP
G.
J.
Microsatellite
F.
K.
A special set of base pairing rules
that apply to the interaction of the
3' base of a codon with an anticodon.
The DNA sequence to which a
trtanscriptional repressor protein
binds.
A process of gene transfer involving
the uptake of fee DNA from solution.
Mutagenic chemical that inserts
between DNA base pairs to cause
InDel mutations.
DNA sequence that is used in E. coli
to determine the relative age of DNA
strands.
Genetic variant that is hypervariable due to high frequency of
slipped mis-pairing during DNA
replication.
Molecule involved in positive
regulation of the E. coli Lac operon in
response to glucose levels.
A process of DNA transfer involving a
DNA element known as a "plasmid".
The copy number variant used for
forensic DNA fingerprinting.
An enzyme that is found in germ-line
cells and some cancer cells, but not
ordinarily in somatic cells of humans.
Formed by the association of nuclear
DNA with histones.