Download Homework #2

BIO 184 Laboratory
CSU, Sacramento
Spring 2005
Homework Assignment #2
Due Friday April 8th
1. A chromosome has the following segments, where ‫ ۝‬represents the centromere:
A
B
‫۝‬
C
D
E
F
G
What type of chromosome mutations are required to change this chromosome into each of
the following chromosomes? (In some cases, more than one chromosome mutation may be
required). Be specific with regards to the movement of segments (meaning use the letters for
reference).
a.
A
B
A
B
‫۝‬
C
D
E
b.
A
B
‫۝‬
C
F
E
D
G
c.
A
B
‫۝‬
C
D
E
d.
A
B
‫۝‬
C
F
E
D
e.
A
B
‫۝‬
C
D
E
F
2.
The following diagram represents two nonhomologous chromosomes:
F
G
F
E
D
G
C
D
F
E
A
B
‫۝‬
C
D
E
F
G
R
S
‫۝‬
T
U
V
W
X
G
What type of chromosome mutation would produce the following chromosomes? Be specific
with regards to the movement of segments (meaning use the letters for reference).
a.
b.
A
B
‫۝‬
C
D
R
S
‫۝‬
T
U
V
W
X
E
F
A
U
V
B
‫۝‬
C
D
E
F
G
R
S
‫۝‬
T
W
X
G
BIO 184 Laboratory
CSU, Sacramento
c.
d.
Spring 2005
A
B
‫۝‬
T
U
V
F
G
R
S
‫۝‬
C
D
E
W
X
A
B
‫۝‬
C
W
G
R
S
‫۝‬
T
U
V
D
E
F
X
3.
A species has 2n = 20 chromosomes. How many chromosomes will be found per cell
in each of the following mutants?
a.
b.
c.
d.
e.
monoploid
triploid
trisomic for chromosome 16 (aneuploid cell type)
monosomic for chromosome 3 (aneuploid cell type)
autotriploid
4. How many Barr bodies are present in humans with the following karyotype?
a) an XY male
b)
c)
d)
e)
an XX female
an XO female
an XXY male
an XXXX female
5.
A young couple is planning to have children. Knowing that there have been a
substantial number of stillbirths, miscarriages, and fertility problems on the husband’s side of
the family, they see a genetic counselor. A chromosome analysis reveals that, whereas the
woman has a normal karyotype, the man possesses only 45 chromosomes and is a carrier of a
Robertsonian translocation between chromosomes 22 and 13.
a) List all the different types of gametes that might be produced by the man.
b) What types of zygotes will develop when each of the gametes produced by the man fuses
with a normal gamete produced by the woman?
c) If trisomies and monsomies entailing chromosome 13 and 22 are letha, what proportion of
the surviving offspring will be carriers of the translocation?
BIO 184 Laboratory
CSU, Sacramento
Spring 2005
6. A female with Turner’s syndrome (XO) is found to be colorblind (X-linked recessive
trait). Both his mother and father have normal vision.
a) Explain how this could have occurred by a nondisjunction event and whether the
nondisjunction occurred in the father or in the mother.
b) Did the nondisjunction event occur in the first or at the second meiotic division (or is
impossible to distinguish given the information)?
c) Repeat the question (both A &B) except substitute Klinefelter’s syndrome (XXY) for
Turner’s syndrome.
7.
Part A. Which of the following relations will be found in the percentages of bases of a
double stranded DNA molecule?
a.
A + T = G + C
b.
A + G = T+ C
c.
A + C = G + T
d.
A + T = 1.0
C +G
e.
A + G = 1.0
C +T
f.
A = G
C
T
g.
A = T
G
C
h.
A = G
T
C
Part B. If 20% of the bases in human are C
a) what percentage are A?
b) what percentage are G?
c) what percentage are T?
BIO 184 Laboratory
CSU, Sacramento
Spring 2005
8.
Part A. An RNA virus that infects plant cells is copied into a DNA molecule once it enters
the plant cell. What would be the sequence of bases in the first strand of DNA made
complementary to the section of viral RNA shown here?
5’ CCCCCAUAAUUCAGCCAGGGGGACUA 3’
Part B. Will the above RNA be able to form a hairpin structure and why?
9. A student mixes some heat-killed type IIIS (smooth) Steptocooccus pneumonia with live
type IIR (rough) and injects the mixture into a mouse. The mouse develops pneumonia and
dies. The student recovers some type IIIS bacteria from the dead mouse.
a. Is this enough evidence that DNA is the transforming principle? Why?
b. How would the student refine the experiment to determine whether DNA is the
transforming agent?
10. Describe how the naked DNA double-stranded helix becomes packaged into the
metaphase chromosome.