1
A sequence of DNA is shown.
5’TAAGAATAACTCCGGCTACGGACTTAGCGCTATTGACGA3’
3’ATTCTTATTGAGGCCGATGCCTGAATCGCGATAACTGCT5’
How many polypeptides can this segment of DNA code for (with a specific start and stop
codon)
zero
+
2
A sequence of prokaryotic DNA is shown. Write the protein sequence (NH3 to –
COO terminus), as well as the RNA sequence (5’ to 3’) coded by this segment of DNA.
Mark the putative transcription start site (AT) and TATA box (TATAAA).
5’ CTAGCGCTTAAAACCCGGGCATCGCCCATCGCCGGCGGCTTTATACGCGTACCGGC 3’
3’ GATCGCGAATTTTGGGCCCGTAGCGGGTAGCGGCCGCCGAAATATGCGCATGGCCG5’
RNA sequence:
5’TGGGCGATGCCCGGGTTTTAAGCGCTAG 3’
Protein sequence:
N-Met-pro-gly-phe-C
3
Shown below is the DNA sequence of a gene from a virus that encodes a
short viral peptide, and also the sequence of the mRNA synthesized from this
gene. genomic DNA sequence:
5'-AGCTCATGTGCGAGTCCTGACGCTGACGTAGG-3'
3'-TCGAGTACACGCTCAGGACTGCGACTGCATCC-5'
Mature mRNA sequence:
5'-UCAUGUGCGAACGCUGACGUAGG-3'
i) In the genomic DNA sequence shown above, draw boxes around the exons.
+
ii) Write the sequence of the peptide encoded by this gene. Indicate the NH3 and
the -COO ends of the peptide.
4
Gene Promoters in prokaryotes interact with what proteins? Gene enhancers in
eukaryotes interact with what class of proteins? Gene promoters in eukaryotes interact
with what proteins?
1
In man, brown eyes (B) is autosomal dominant over blue eyes (b).
A heterozygous brown eyed woman marries a blue eyed man. What will be the
genotypes, phenotypes (ratios) of the children.
Bb
x bb
F1 Bb bb
1 1
In man, brown eyes (B) is autosomal dominant over blue eyes (b).
In a family of nine children, two have blue eyes and seven have brown eyes. What is the
most likely genotype and phenotype of the parents
Bb and Bb
2
You are given a red-eyed male fly. The genotype of this fly is not known.
Red eye is an autosomal dominant trait and in the lab you have true breeding red-eyed
and white-eyed flies. Diagram a single cross you would need to do and the expected
results you would get in order to unambiguously determine the genotype of the red-eyed
fly.
TEST cross with white eyed female.
If male is homozygous all F1 will be red eyed
If male is heterozygous 50% in F1 will be red eyed and 50% will be white
3
An X-linked dominant allele of a gene causes high blood pressure in humans. A
man with high blood pressure marries a woman with normal blood pressure. What
proportions of their sons will have high blood pressure?
H= high blood pressure h= normal blood pressure
Cross is H/Y x h/h
Progeny H/h females and h/Y males. Answer is zero.
4
Two genes T and S code for height and skin tone in vampires. (T=tall, t=short;
S=smooth, s=wrinkled). A heterozygous TtSs individual mates with a homozygous ttss
individual. They have progeny: 39 tall wrinkled; 40 short smooth; 9 tall smooth; 10 short
wrinkled. Are the two genes linked or on separate chromosomes. If linked what is the
distance between these two genes.
If the two are not linked then you should see 1:1:1:1 of the four classes. You don’t.
Therefore the genes are linked.
Parental class should be at least 50%. Therefore 39 and 40 are parental class and 10
and 9 are recombinant. MU= 19/98 19%
5
How many different kinds of gametes can a AaBbcc individual form
4
How many types of gametes will an individual of the genotype AaBBCcDDEEFfGG
produce?
8
6
Autosomal genes B and F are separated by a distance of 15 MU. Female
Drosophila with one homolog bearing the B---f alleles and the other homolog bearing the
b----F alleles are crossed to males doubly homozygous for the recessive alleles of these
genes.
A
list the genotypes and frequency of gamete classes produced by the male
Genotype= bbff
One gamete class= bf
B
list the genotypes and frequency of gamete classes produced by the female
Genotype=
B---f
b----F
gamete classes
Parental
B----f
b----F
recombinant B----F
b----f
0.425
0.425
0.075
0.075
C
What proportion of the progeny from this cross will be Bbff
bf
______________________________
0.425 Bf
Bbff
0.425 bF
bbFf
0.075 BF
BbFf
0.075 bf
bbff
0.425
D
E
7
What proportion of the progeny from this cross will be bbff
0.075
what proportion of the progeny from this cross will be BBFF
0
Diagram mitosis in haploid cells with 2 different chromosomes
8
Which events occur in both mitotic and meiotic cells while which events occurs
only in meiosis?
9
What is the Chromosome theory of inheritance?
What is the biological basis (mechanism) of Mendel’s law of independent assortment?
10
What are the characteristics of a X-linked trait?
11
Assume this is the pedigree of a family with retinitis pigmentosa.
What is the most likely mode of inheritance of this trait?
Y linked inheritance.
Can you determine if this trait is dominant or recessive? Explain your answer
If you can determine that the trait is dominant or recessive, what is it?
(You cannot determine if this is dominant or recessive)
Using the nomenclature R= normal allele and r = mutant allele
What is the genotype of individual :
II-1 (X/Yr),
III-2 (X/YR)
III-5 (X/Yr)
12
A farmer maintains two true-breeding lines of strawberries- sweet tasting strain
and a bitter tasting strain. He crosses these two strains and in the F1 obtains plants that
produce tangy tasting berries. He crosses the F1 to themselves in the hope of obtaining a
true-breeding tangy tasting berry. In the F2 only half the plants are tangy tasting. The rest
have either sweet or bitter tasting berries. Explain this pattern of inheritance.
Incomplete dominance
13
Consider the following data from F1-derived test-cross progeny from a cross of
two homozygous parents. Alleles in each parent are in coupling
Genotype
VvWw
Vvww
vvWw
vvww
No. of progeny
40
10
10
40
What are the recombinant genotypes
Vvww and vvWw
What is the percentage of recombination between the two loci
20%
14
An individual heterozygous for three genes (AaBbCc) is test-crossed to an aabbcc
individual and the progeny are classified by the gamete contribution from the
heterozygous parent as follows
a-b-c
158
A-B-c
299
A-B-C
142
a-B-c
48
A-b-C
51
A-b-c
8
a-B-C
10
a-b-C
282
A)
Are the three genes linked
YES
B)
Which alleles are present on each of the parental chromosomes. Show your
reasoning.
The most frequent classes represent parental class
Allelic configuration: ABc and abC
C)
What is the order of these genes on the parental chromosomes
Gene order is ABC
D)
Indicate map distance between these three genes
ABc
abC
299
282
P
abc 158
ABC 142
SCOII
aBc 48
AbC 51
SCOI
Abc
aBC
DCO
A to B
B to C
8
10
48+51+10+8/998 = 11.7
158+142+10+8/998 = 31.9
E) Is interference occurring
Expected DCO = 0.117 x 0.319 x 998 = 37
Observed DCO = 10+8=18
Yes interference is occurring. Observed is far less than expected.
15
What are the factors that alter recombination frequency?
________________________________________________________________________
_______________________________________________________________________
16
The diagram shows a biochemical pathway for flower pigment biosynthesis.
Normally, enzymes A, B and C cooperate to produce PURPLE flowers (i.e. PURPLE
results from a mixture of RED and BLUE pigments). In this case, very little of the
YELLOW pigment remains because it is all converted to RED or BLUE.
Assume that the genes for enzymes A, B, and C are unlinked.
--B-----Red
/
Precursor--A yellow|
+
=Purple
\
--C----Blue
A. You have true-breeding RED plants and true breeding BLUE plants. If these are
crossed,
What is the genotype of the parents?
The RED plants are AA BB cc.
The BLUE plants are AA bb CC.
What result (genotype and phenotypic ratios) do you expect in the F1 generation?
The F1's are AA Bb Cc.
ALL PURPLE
B. What phenotypic ratios do you expect in the F2 when the F1’s are self crossed?
9 PURPLE
3 RED
3 BLUE
1 YELLOW
17
Three unlinked genes code for enzymes involved in eye color in dogs
gray--------------------->gray------------------->gray---------------------->red
enzymeX
enzymeY
enzymeZ
A true breeding red eye dog is crossed with a gray eyed x/x y/y z/z dog to give a F1. The
F1 is selfed. What proportion of the F2 individuals will be gray?
37/64
18
Seven mutations are isolated in the haploid banana slug- all of which require
compound X to grow. The precursors in the pathway that leads to the production of
compound X are known. These include compounds B, H, I, S, T and X. Each of the
compounds is tested for its ability to support growth of each of the seven mutations. In
the table, + indicates growth and – indicates no growth.
1
2
3
S
-
T
+
-
I
-
H
+
+
-
B
-
X
+
+
+
4
+
+
+
+
5
+
+
+
+
+
6
+
+
+
7
+
+
What is the order of compounds B, H, I, S, T and X in the biochemical pathway?
At what point in the pathway is each of the mutations blocked?
B
S
5
I
4
T
2,6
1,7
H
3
X
19
In Drosophila mutants A, B, C, D, E, F and G all have the same phenotype:
absence of red pigment in the eye. In pairwise combinations in complementation tests,
the following results were produced where + is complementation and – is non
complementation.
A
B
C
D
E
F
G
G
+
+
+
+
+
F
+
+
+
E
+
+
+
D
+
+
C
+
+
B
+
A
How many complementation groups are present
Which mutants are in which complementation group
How many genes are present in this pathway
There are three complementation groups
A,f,d
B, g
C,e
21
What are nonsense mutations and what are nonsense suppressor mutations?
22
After sequencing the wildtype TOU gene obtained from a genomic
plasmid clone you find a 32 base pair insertion in the middle of it that does not
correspond to the mRNA for wild type TOU. What is it?
Intron
Assume mRNA is being transcribed starting from the far left side of the following
double stranded DNA template.
5’GTGCTAGCGGGAATGAGCTGGGATACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACCCTATGATCATCCCGA5’
a) What are the first five nucleotides of the mRNA sequence? _GUGCU___________
b) What are the first 5 amino acids encoded? _______MSWDT_________________
c) The following sequences show (in bold) different mutations affecting the DNA
sequence. Assume none affect the expression of the mRNA synthesis.
A. 5’GTGCTGAGCGGGAATGAGCTGGGATACTAGTAGGGCT3’
3’CACGACTCGCCCTTACTCGACCCTATGATCATCCCGA5’
B. 5’GTGCTAGCGGGAATGAGCTGCGGATACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACGCCTATGATCATCCCGA5’
C. 5’GTGCTAGCGGGAATGAGCTGAGATACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACTCTATGATCATCCCGA5’
D. 5’GTGCTAGCGGGAATGAGCTGGGAAACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACCCTTTGATCATCCCGA5’
E. 5’GTGCTAGCGGGAATGAGCTGGGACACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACCCTGTGATCATCCCGA5’
F. 5’GTGCTAGCGGGAATGAGCTGGCATACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACCGTATGATCATCCCGA5’
WT 5’GTGCTAGCGGGAATGAGCTGGGATACTAGTAGGGCT3’
3’CACGATCGCCCTTACTCGACCCTATGATCATCCCGA5’
i) For the above mutations, fill in the following box.
Sequence
Type of mutation
Effect on protein
Choose from insertion, deletion, substitution.
Choose from missense, nonsense,
frameshift, silent.
A
Insertion
Silent
B
Insertion
Frameshift
C
Substitution
Nonsense
D
Substitution
Missense D to E
E
Substitution
Silent
F
Substitution
Missense D to H
ii) Order the mutations according to the likelihood that they will result in an inactive
protein, from most likely to least likely. If you think two mutations have an equal
likelihood of resulting in an inactive protein, write an equal sign between them. Your
answer should be in the format X>Y>Z=V=WT(wild type).
C≥B>F>D>E=A=WT
23
What are Northern blots and what are Southern blots. Discuss the similarities and
differences between these two techniques?
24
Use the data below to construct a restriction map for an unknown plasmid.
EcoRI 3.9
3.7
HindIII4.0
2.1
PstI 4.0
3.6
EcoRI + HindIII
EcoRI + PstI 3.3
HindIII + PstI 2.1
1.5
2.7
3.0
1.9
2.1
0.7
1.7
1.3
0.6
1.5
1.2
0.3
0.4
25
You need to amplify the following double stranded DNA sequence using PCR.
Design the two primers (10 nucleotides long) that will allow you to accomplish this task.
Write the sequence of these two primers in the 5’ to 3’ orientation
ATGGTCCATGCTGACTGCGATGCATGCTGAAATGGCCTTAATGGGTAAA
TACCAGGTACGACTGACGCTACGTACGACTTTACCGGAATTACCCATTT
Primer1: 5’ATGGTCCATG3’
Primer2: 5’TTTACCCATT3’
26
How will a cDNA library made from female dog liver differ from a cDNA library
made from female dog erythrocytes?
27
A restriction map of the plasmid is shown
The location of a probe is shown. (4.5 kb E-H fragment spanning the Mst1 site)
This plasmid is digested with different enzymes and probed with the probe in a Southern
blot. What are the sizes of the bands that will be produced from a
EcoR1 digest 7
Hpa1 digest 13.5
EcoR1 + Hpa1 digest
4.5kb
Mst1 digest 11.5 and 11.5
Draw the bands for each digest on the blank gel given below. The DNA molecular weight
marker is shown on this gel.
28
29
A restriction map of chromosomal DNA containing the autosomal gene – Notch is
shown. The top restriction map is for the wild-type gene while the bottom map is for the
mutant gene. The EcoRI fragment containing the entire gene is used as a probe in
Southern blots.
A heterozygous female fly is crossed to a notch winged male fly.
Chromosomal DNA is isolated from the progeny, digested with SmaI and a Southern blot
of the digested DNA is probed with the Notch gene probe. Draw a punnet square of the
expected fragment sizes (on the Southern blot) in the progeny from this cross.
The wild-type notch gene resides on a 5 and 2 kb SmaI fragment. The mutant notch
gene resides on a 7 kb SmaI fragment.
30
On the X chromosome resides the eye color gene. W+ gives red eyes while the
recessive allele w- gives white eyes. On the same chromosome there is the following
RFLP:
StrainA (true breeding)-------E-----------------------9kb---------------------------E------StrainB (true breeding)-------E------4kb------------E----------------5kb----------E-------In addition a probe is identified that on a southern blot of EcoRI digested genomic DNA
from strain A and strain B produces the following pattern:
StrainA
______
|____ |9kb
|
|
|
|
|
|
|
|
|_____ |
StrainB
______
|
|
|
|
|____ |5kb
|
|
|____ |4kb
|_ ____|
With respect to the restriction sites shown above, indicate the position of the probe
Probe resides across the Eco site in the middle
A white eyed strainA male is crossed to a true breeding strainB female that is
homozygous for the red eyed gene. The F1 females are crossed to normal eyed males.
The resulting male progeny were scored for eye color and the southern blot pattern of
EcoRI digested DNA using the above probe. The following results were obtained:
Eye color:
Southern blot:
white
white
normal
normal
______
______
______
______
|____ |
|
|
|____ |
|
|
|
|
|____ |
|
|
|____ |
|
|
|
|
|
|
|
|
|
|
|____ |
|
|
|____ |
|_____ |
|_____ |
|_____ |
|_____ |
Number of progeny 330
280
270
320
Which of these four progeny classes are parental and which are recombinant?
Parental = 330 and 320
What is the map distance between the W+ gene and the RFLP
550/1200= 45.8