11. Lab 7 Chromosomal Mutations

11. Lab 7 Chromosomal Mutations -...

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Unformatted text preview: Lab
7

Chromosomal
Mutations

































Name:_____________________________________
 
 26
marks
 
 
 
 
 
 
 
 SSID:_________________________
 1. (3
marks
total)
 Why
do
most
polyploidy
species
tend
to
have
even
numbers?
(E.g.,
 Why
are
triploid
 species
 almost
always
sterile?)
b)
 How
would
you
account
for
the
appearance
of
individuals
with
an
 odd
number
of
chromosomes
(that
is,
21,
39,
etc.)
in
series
of
polyploidy
species
with
2n
=
20,
40,
60,
 80?
 
 
 2. (3
marks
total)
The
following
chromosomes
are
related
to
each
other
by
a
series
of
inversions
and
are
 listed
 in
 the
 order
 in
 which
 they
 arose.
 
 For
 each
 of
 these
 changes,
 indicate
 on
 the
 preceding
 chromosome
(the
one
above),
with
arrows,
the
breakpoints
that
would
give
rise
to
each
inversion.
 
 
 
 I:
A

B

C

D

E

F

*

G

H

I

J

 II:
A

B

F

E

D

C

*

G

H

I

J
 III:
A

B

F

E

H

G

*

C

D

I

J
 IV:
A

B

F

E

H

G

*

I

D

C

J
 3. (3
marks
total)
Distinguish
between
pseudodominance,
pseudogenes,
and
pseudolinkage.
 
 
 
 
 
 
 
 
 
 Lab
7

Chromosomal
Mutations

































Name:_____________________________________
 
 4. 
(1
 mark)
 Gene
 mapping
 experiments
 on
 a
 species
 of
 plant
 show
 that
 all
 genes
 belong
 to
 a
 single
 linkage
 group
 even
 though
 the
 plant
 is
 known
 to
 have
 four
 pairs
 of
 chromosomes.
 What
 could
 account
for
this?
 
 5. (1
mark)
Consider
the
following
wild‐type
&
mutant
sequences:
 
 
 WT
 
 …CTTGCAAGCGAATC…
 
 
 Mutant
 …CTTGCTAGCGAATC…
 The
substitution
shown
seems
to
have
created
a
stop
codon.
What
further
information
do
you
need
 to
be
confident
that
it
has
done
so?
 
 
 
 
 6. (3
mark
total)
 Hypothetically
speaking,
a
particular
protein
named
AWAKE
is
1
000
amino
acid
&
is
 known
to
be
involved
in
producing
the
phenotype
‘awake
in
8:30
am
classes’.

Some
individuals
were
 genotyped
&
had
a
deletion
of
2
nucleotides
near
the
5’
end
of
the
AWAKE
gene.

Other
individuals
 have
a
deletion
of
99
bases
in
the
same
region.
a)
(1
mark)
What
is
the
length
of
the
AWAKE
gene?
b)
 (2
marks)
 Explain
which
mutation
 you
think
would
be
more
likely
to
be
the
most
deleterious
to
the
 AWAKE
phenotype
 
 
 
 
 
 Lab
7

Chromosomal
Mutations

































Name:_____________________________________
 7. (6
marks
total)
 Certain
mice
called
 waltzers
have
a
recessive
mutation
that
causes
them
to
execute
 bizarre
 steps.
 W.H.
 Gates
 crossed
 waltzers
 with
 homozygous
 WT
 mice
 and
 found,
 among
 several
 hundred
 normal
 progeny,
 a
 single
 waltzing
 female
 mouse.
 When
 mated
 with
 a
 waltzing
 male,
 she
 produced
 all
 waltzing
 offspring.
 
 When
 mated
 with
 a
 homozygous
 normal
 male,
 she
 produced
 all
 normal
 progeny.
 
 Some
 males
 &
 females
 of
 this
 group
 of
 normal
 progeny
 were
 intercrossed,
 and
 there
were
no
waltzing
offspring
among
their
offspring.

T.S.
Painter
examined
the
chromosomes
of
 waltzing
mice
that
were
derived
from
some
of
Gates’s
crosses
&
that
showed
a
breeding
behaviour
 similar
 to
 that
 of
 the
 original,
 unusual
 waltzing
 female.
 He
 found
 that
 these
 mice
 had
 40
 chromosomes,
just
as
in
normal
mice
or
the
usual
waltzing
 mice.

In
the
unusual
waltzers,
however,
 one
member
of
a
chromosome
pair
was
abnormally
short.

 Diagram
the
crosses
(3
marks),
and
then
 interpret
 these
 observations
 as
 completely
 as
 possible,
 both
 genetically
 &
 cytogenetically
 (noting
 what
results
you
would
have
gotten)
(3
marks).
 Lab
7

Chromosomal
Mutations

































Name:_____________________________________
 8. (6
 marks)
 Six
 bands
 in
 a
 salivary‐gland
 chromosome
 of
 Drosophila
 are
 shown
 in
 the
 following
 illustration,
along
with
the
extent
of
5
deletions
(Del
1

Del
5):

 Recessive
alleles
a,
b,
c,
d,
e,
and
f,
are
known
to
be
in
the
region,
but
their
order
is
unknown.
When
the
 deletions
are
combined
with
each
allele,
the
following
results
are
obtained:
 
 
 
 
 In
 this
 table,
 a
 minus
 means
 the
 deletion
 is
 missing
 the
 corresponding
 WT
 allele
 (i.e.,
 the
 deletion
 uncovers
the
recessive),
and
a
plus
sign
indicates
that
the
corresponding
WT
allele
is
still
present.

Use
 these
 data
 to
 infer
 which
 band
 on
 the
 salivary
 chromosome
 contains
 each
 gene
 and
 fill
 in
 the
 chart
 below.
(Determine
the
order
of
the
genes.)

 
 
 
 
 
 Chromosomal
 Gene
 Band
 1
 
 2
 
 3
 
 4
 
 5
 
 6
 
 ...
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This note was uploaded on 01/10/2010 for the course BIOLOGY biol2040 taught by Professor Tamarakelly during the Fall '09 term at York University.

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