Exam 1 explanation

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Unformatted text preview: 1)
A
major
difference
between
gametogenesis
in
males
and
females
is
the
existence
of
numerous
 germline
stem
cells
in
the
adult
male.
In
the
female
fetus,
the
germline
stem
cells
enter
meiosis
and
 are
arrested
in
prophase
I.
Over
the
years,
as
these
germline
stem
cells
mitotically
 divide,
they
can
accumulate
mutations
that
can
then
be
transmitted
to
his
offspring.
If
a
germline
 stem
cell
accumulates
a
mutation,
this
will
be
passed
on
to
offspring
by
the
sperm.
 A)
True
B)
False
 
 2)
RT‐PCR
is
used
to
quantify
how
much
message
is
present
in
an
embryo
and
identify
which
 cells
in
the
embryo
are
expressing
the
message.
RT‐PCR
alone
can
not
identify
which
cells
are
 expressing
the
message,
because
RNA
is
prepared
from
a
mixture
of
cell
types.
 A)
True
B)
False
 
 3)
The
objective
of
a
microarray
experiment
is
to:
 A)
Identify
differences
in
protein
content
between
two
samples.
To
compare
protein
content
you
 could
run
an
acrylamide
gel
–
stain
the
gel
–
use
mass
spectral
approaches
to
identify
proteins.
 B)
Identify
differences
in
mRNA
populations
between
two
samples.
 C)
Identify
proteins
that
interact
within
a
cell..
describes
co‐immunoprecipitation
 D)
Identify
cells
that
express
an
mRNA.
Describes
and
in
situ
hybridization
 3)
 4)
If
a
blastocyst
is
cultured
in
vitro,
the
trophoblast
cells
attach
to
the
petri
dish
and
migrate
 away
from
the
inner
cell
mass.

 A)
True
B)
False
 
 5)
4)
 The
inner
cell
mass
cells
of
the
early
blastocyst
give
rise
to
which
tissue(s)
at
the
egg‐cylinder
 stage?:
 A)
visceral
endoderm
and
extra‐embryonic
ectoderm.
 B)
epiblast
and
extra‐embryonic
ectoderm.
 C)
epiblast
 D)
epiblast,
visceral
endoderm
and
parietal
endoderm.
 
 6)
Embryonic
stem
cells
can
be
triggered
to
differentiate
into
primitive
endoderm
by:
 A)
elevating
the
level
of
Cdx2
B)
reducing
the
level
of
Oct4
 C)
elevating
the
level
of
Gata6
D)
Both
A
and
B
 
 7)
Over
expression
of
Nanog
in
embryonic
stem
cells:
 A)
triggers
differentiation
regardless
of
culture
conditions.
 B)
suppresses
differentiation
of
ES
cells
in
the
absence
of
leukemia
inhibitory
factor
(LIF).
 C)
triggers
differentiation
in
the
absence
of
leukemia
inhibitory
factor
(LIF).
 D)
triggers
differentiation
of
primitive
endoderm
cells
in
the
presence
of
leukemia
 inhibitory
factor
(LIF).
 
 8)
The
chromatin
are
very
compact
in
the
sperm
nucleus
because
protamines
are
replaced
with
 histones.
Histones
are
replaced
with
protamines.
 A)
True
B)
False
 
 9)
If
Cdx2
is
expressed
in
a
cell:
 A)
Lats
is
phosphorylated
This
would
suppress
Cdx2
expression
B)
Yap
is
phosphorylated
This
would
 suppress
Cdx2
expression
 C)
Yap
and
Tead4
are
nuclear
D)
Tead4
is
nuclear
Tead4
can
not
work
without
Yap
in
the
nucleus
 
 
 
 
 10)
Which
of
the
following
would
you
expect
from
exposure
to
BPA
in
drinking
water?
 A)
Increased
incidence
of
congression
failure
 B)
Increased
incidence
of
aneuploidy
 C)
Decrease
in
fertility
 D)
All
the
above
 
 11)
A
Nanog
mutant
embryo
will:
 A)
Fail
to
implant,
differentiate
primitive
endoderm,
and
lack
epiblast
cells.
 B)
Fail
to
implant
and
will
differentiate
primitive
endoderm
cells.
 C)
Implant,
differentiate
both
primitive
endoderm
and
epiblast
cells.
 D)
Implant,
differentiate
primitive
endoderm,
and
lack
epiblast
cells
 
 12)
The
order
in
which
the
mouse
blastomeres
divide
at
the
2‐cell
stage
specifies
whether
the
cells
 will
become
outer
trophectoderm
or
inner
cell
mass
cells.
The
order
will
influence
if
the
cell
will
be
 localized
more
toward
the
embryonic
or
abembryonic
end.
However,
the
embryonic
and
 abembryonic
poles
contain
both
trophectoderm
and
inner
cell
mass
cells.
 A)
True
B)
False
 
 13)
In
the
mouse
embryo,
the
zygotic
genes
are
first
activated
at:
 A)
the
compacted
morula
stage
B)
the
two‐cell
stage
 C)
fertilization
D)
the
blastocyst
stage
 
 14)
If
a
male
can
not
produce
GalT,
he
will
be
infertile
because
sperm
will
be
unable
to
bind
to
the
 zona
pellucida.
This
infertility
could
be
overcome
using
intracytoplasmic
sperm
injection
(ICSI)
 to
introduce
the
sperm
nucleus
into
an
egg.
ICSI
is
used
to
overcome
defects
in
sperm
motility
or
 binding.
Since
the
GalT
mutation
should
not
affect
the
male
pronucleus,
this
approach
is
reasonable.
 A)
True
B)
False
 
 15)
If
a
Yap
mutation
prevents
phosphorylation
by
Lats,
how
do
you
predict
this
will
this
affect
 development
of
the
embryo?
In
this
situation,
Yap
would
never
be
phosphorylated,
and
is
expected
to
 enter
the
nucleus
where
it
will
work
with
TEAD4
and
activate
Cdx2
–
triggering
trophoblast
 differenctiation.
 A)
The
outer
cells
will
polarize
and
the
inner
cells
will
remain
unpolarized.
 B)
All
cells
will
differentiate
into
trophectoderm.
 C)
All
cells
will
express
Oct4
and
will
remain
pluripotent.
 D)
All
cells
will
express
Cdx2
and
will
remain
pluripotent.
 
 16)
Variation
in
aneuploidy
rates
in
mice
housed
at
different
animal
facilities
could
result
from:
 A)
differences
in
chemical
composition
of
feed
 B)
genetic
variation
in
the
animals
 C)
differences
in
environmental
contaminants
 D)
All
the
above
 
 17)
In
a
chimera,
Gata6
mutant
cells
are
found
throughout
the
developing
lung,
but
are
excluded
 from
the
developing
bronchial
epithelium
in
the
lung.
The
best
interpretation
of
these
results
 is:
 A)
Gata6
function
is
required
in
cells
that
differentiate
into
the
bronchial
epithelium.
 B)
Gata6
is
needed
for
endoderm
differentiation.
 C)
Loss
of
Gata6
can
be
compensated
by
Gata4.
 D)
Gata6
function
is
essential
in
all
cells
of
the
lung.
 
 
 
 
 18)
What
experimental
evidence
suggests
that
Gata6
is
important
for
primitive
endoderm
 differentiation?
 A)
Gata6
expression
is
observed
in
selected
inner
cell
mass
in
the
early
blastocyst
and
in
the
 primitive
endoderm
of
the
late
blastocyst.
 B)
Knockout
of
Gata6
in
the
mouse
embryo
results
in
defects
in
the
apical
structure
of
the
 primitive
endoderm.
 C)
Overexpression
of
Gata6
in
embryonic
stem
(ES)
cells
induces
differentiation
of
 primitive
endoderm.
 D)
All
the
above.
None
of
these
on
their
own
are
sufficient
to
support
this
conclusion‐combined,
these
 data
build
a
case
for
Gata6’s
role
in
primitive
endoderm
cell
fate
determination.
 
 19)
The
consequenceof
congression
failure
is:
 A)
inability
to
complete
meiosis
B)
similar
sized
oocyte
and
polar
body
 C)
aneuploidy
D)
polyspermy
 
 20)
In
the
Cdx2
knockout,
a
blastocoel
begins
to
form
in
some
mutant
embryos.
These
results
 suggest
that:
 A)
The
inner
cell
mass
produces
the
blastocoel.
 B)
The
knockout
does
not
completely
get
rid
of
Cdx2.
 C)
Cell
death
is
occuring
and
creating
a
blastocoel.
 D)
Cdx2
does
not
activate
all
genes
needed
for
trophoblast
cell
function.
 
 21)
To
establish
that
a
gene
product
regulates
a
developmental
process,
one
must
demonstrate
 that:
 A)
activation
or
overexpression
of
the
gene
can
trigger
the
developmental
process.
 B)
the
gene
is
expressed
at
the
right
time
and
place
in
the
embryo.
 C)
loss
of
the
gene
disrupts
the
developmental
process.
 D)
as
many
of
the
above
as
possible.
Never
rely
on
a
single
experimental
approach.
For
example,
 similar
proteins
may
exert
similar
affects
on
an
embryo
but
be
expressed
in
radically
different
times
 and
places.
If
they
are
expressed
in
similar
places,
loss
of
one
may
obscure
the
function
of
the
other.
 
 22)
The
inner
cell
mass
cells
of
a
blastocyst
can
be
identified
by:
 A)
nuclear
expression
of
Oct4.
 B)
basement
membrane
expression
of
integrin
alpha
7.
 C)
nuclear
expression
of
Tead4.
 D)
nuclear
expression
of
Yap.
 
 23)
If
both
the
mother
and
father
are
heterozygous
for
a
null
mutation
in
ZP3,
then
1/4
of
their
 offspring
will
lack
a
zona
pellucida
and
fail
to
develop.
ZP3
is
made
by
the
mom
and
deposited
 around
the
egg.
If
the
mom
is
heterozygous,
then
all
her
eggs
will
have
a
zona
pellucida
and
will
be
 fertilized.

 A)
True
B)
False
 
 24)
How
is
cell
polarity
predicted
to
influence
trophoblast
differentiation
in
the
compacted
 morula?
 A)
Triggers
phosphorylation
of
Yap
and
activates
Cdx2
expression.
 B)
Activates
the
Lats,
suppressing
Cdx2
expression.
 C)
Activates
nuclear
Yap
and
supresses
Cdx2
expression.
 D)
Supresses
the
Hippo
pathway
and
activates
Cdx2
expression.
 
 
 
 
 
 
 25)
Which
of
the
following
observations
provides
evidence
that
Floped
protein
in
the
 pre‐implantation
mouse
embryo
does
not
result
from
zygotic
gene
activation?
 A)
Floped
protein
is
absent
in
1/2
the
oocytes
from
Figlia
mutant
moms.
 B)
Floped
protein
is
only
present
in
the
developing
oocyte.
 C)
Although
Floped
protein
is
abundant
in
the
morula,
little
or
no
message
is
present
after
 the
late
oocyte
stage.
 D)
Zygotic
gene
expression
in
the
mouse
is
not
activated
until
the
blastocyst
stage.
 
 26)
Because
chimeras
derived
from
the
animal/vegital
cells
produce
viable
offspring
and
chimeras
 derived
from
vegital
cells
are
inviable,
we
can
conclude
that
there
are
localized
maternal
 factors
in
the
mouse
egg
that
specify
the
fate
of
the
blastomere.
No
–
there
is
still
a
possibility
that
the
 “mosaicness”
results
from
zygotic
activation
of
different
gene
in
AV,
A,
or
V
blastomeres.
 A)
Ture
B)
False
 
 27)
A
co‐immunoprecipitation
experiment
is
used
to
identify:
 A)
the
sub‐cellular
localization
of
an
mRNA
or
protein
 B)
mRNAs
regulated
by
a
similar
transcription
factor.
 C)
proteins
that
potentially
interact
with
one
another
in
a
cell.
 D)
targets
of
transcription
factors
 
 28)
The
primitive
endoderm
expands
into
the
visceral
endoderm
which
functions
to:
 A)
Absorb
nutrients
for
the
embryo
(before
the
placenta
forms)
and
provide
signals
needed
 to
establish
embryo
polarity
 B)
Provide
cells
that
will
become
the
liver,
lung,
and
gut.
This
is
the
definitive
endoderm
 C)
Form
the
chorion
–
this
would
be
the
trophoblast
 D)
Make
a
barrier
between
the
trophoblast
and
the
epiblast.
This
is
the
parietal
endoderm
 
 29)
How
will
the
Oct4
knockout
affect
gene
expression
and
blastomere
differentiation
in
the
 embryo?
 A)
Both
Cdx2
and
gata6
will
be
expressed
and
blastomeres
will
differentiate
into
 trphoectoderm
and
primitive
endoderm.

 B)
Nanog
will
be
activated
and
blastomeres
will
differentiate
into
epiblast
precursors.
 C)
Cdx2
will
be
expressed
and
blastomeres
will
differentiate
into
trophectoderm.
 D)
Gata6
will
be
expressed
and
blastomeres
will
differentiate
into
primitive
endoderm.
 
 30)
Characteristics
of
a
Trophoblast
cell
include:
Apical/basal
polarity;
Basally
localized
SCMC
 complex
SCMC
is
apically
localized,
PKCzeta,
and
Ezrin;
Elevated
expression
of
Cdx2;
and
cytoplasmic
 localized
Yap
and
Tead4.
Yap
and
Tead4
should
be
nuclear
localized
 A)
True
B)
False
 
 31)
Eggs
collected
from
a
woman
undergoing
infertility
treatment
lack
a
zona
pellucida.
After
ICSI
 (intracytoplamic
sperm
injection)
,
the
resulting
cleavage
blastomeres
are
irregular
in
size
and
a
 compacrted
morula
fails
to
form.
What
is
a
possible
cause
of
her
infertility?
If the female was only mutant in ZP3, then fertilization by ICSI would have resulted in an embryo with normal SCMC and normal cleavage. Since the oocyte lacked a zona and also could not undergo correct cleavage, both zona pellucida and SCMC must have been affected. The only choice left is that Figlia was defective. 
 A)
mutations
in
Figlia
B)
mutations
in
ZP3

 C)
mutations
in
ZP2
D)
all
the
above
neither
B
nor
C
will
cause
defects
in
blastomere
size
and
 compaction
of
the
morula.
 
 32)
Because
the
mammalian
egg
is
so
small,
maternal
factors
are
not
important
for
mammalian
 embryo
development.
No,
we
discussed
data
supporting
that
SCMC
complex
componets
are
maternal
 factors.
 A)
True
B)
False
 
 33)
Which
of
the
following
observations
provides
evidence
that
the
male
and
female
pronuclei
 contain
distinct
genetic
information?
 A)
After
fertilization,
the
histones
in
the
male
pronucleus
are
replaced
by
protamines.
Demonstrates
 protein
differences
 B)
After
completion
of
the
second
meiotic
division,
the
female
pronucleus
becomes
the
 polar
body.
 C)
When
an
embryo
inherits
a
male
pronucleus
it
develops
with
male
sexual
characteristics.
 D)
Even
though
diploid,
gynogenetic
and
androgentic
embryos
fail
to
develop
properly.
 
 34)
What
can
we
conclude
about
the
role
of
ZP3
in
species
recognition
by
the
sperm
from
 fertilization
experiments
using
the
ZP3
knockout
with
humanized
ZP3?
 A)
ZP3
is
essential
for
species
specific
binding
of
the
sperm
to
the
zona
pellucida.
 B)
ZP3
has
no
role
in
species
specific
binding.
 C)
There
is
insufficient
data
to
conclude
what
confers
species
specific
sperm
binding.
 D)
Human
ZP3
does
not
function
in
the
mouse
zona
pellucida.
 
 35)
If
a
female
mouse
is
Floped
‐/‐
and
mates
to
a
Floped
+/‐
male,
how
will
their
offspring
 develop?
Floped
is
maternally
supplied,
so
none
of
the
eggs
from
a
flopped
‐/‐
mother
will
have
 flopped
protein
–
the
SCMC
will
not
form
without
Floped.

 A)
All
embryos
will
develop
normally.
 B)
All
embryos
will
show
abnormal
cleavage,
and
will
not
localize
the
SCMC.
 C)
1/2
the
embryos
will
fail
to
localize
the
SCMC
and
will
die
during
cleavage.
 D)
1/2
the
embryos
will
fail
to
localize
Yap
in
the
nucleus
of
the
outer
cells
in
the
 compacted
morula.
 
 36)
Which
observation(s)
support
the
hypothesis
that
FLOPED,
MATER,
and
TLE6
form
a
 Subcortical
Maternal
Complex?
 A)
Floped,
Mater,
and
TLE6
co‐immunoprecipitate.
 B)
Floped,
Mater,
and
TLE6
localize
to
the
same
apical
cellular
region
 C)
Mutations
in
Floped
disrupt
localization
of
Mater.
 D)
All
the
above
 
 37)
Precursors
of
the
primitive
endoderm
and
epiblast
are
formed
as
trophoblast
cells
divide
 orthogonal
(perpendicular)
to
the
axis
of
trophoblast
cell
polarity.
As
a
consequence,
the
 primitive
endoderm
and
epiblast
precursors
are
mixed
within
the
inner
cell
mass
and
must
 move
or
sort
to
form
the
epiblast
and
primitive
endoderm
layers.
 A)
True
B)
False
 
 38)
Which
of
the
following
observation(s)
support(s)
the
conclusion
that
the
sperm
binds
to
ZP3
in
 the
zona
pellucida?
 A)
human
monoclonal
antibody
against
ZP3
blocks
the
ability
of
mouse
sperm
to
fertilize
a
 mouse
oocytes
with
human
ZP3.
NOTE
THAT
I
ACCEPTED
ALL
ANSWERS
BECAUSE
OF
THE
 CONFUSION.
I
THINK
THAT
SOME
EXAM
FORMS
SCRAMBLED
B
AND
C.
 B)
pre‐incubation
of
sperm
with
purified
ZP3
reduces
the
rate
of
oocyte
fertilization.
 C)
human
ZP3
can
restore
the
ability
to
make
a
zona
pellucida
in
transgenic
females
that
 lack
mouse
ZP3.
–
this
observation
does
not
say
anything
about
sperm
binding

‐
so
is
really
 incorrect.
 D)
a
and
b

 
 39)
Germ
cell
specification
in
Drosophila
is
an
example
of
regulative
development
–
no
–
this
would
 be
an
example
of
mosaic
development.
 A)
True
B)
False
 
 40)
Gene
trap
insertions
randomly
insert
into
the
genome.
If
it
inserts
within
a
gene,
a
reporter
 gene
such
as
LacZ
or
GFP
will
be
activated
wherever
the
gene
is
normally
expressed.
As
a
 consequence,
the
gene
trap
insertion
creates
a
mutant
allele
and
also
provides
information
on
 where
and
when
the
gene
is
normally
expressed.
 A)
True
B)
False
 
 41)
The
trophoblast
cells
adjacent
to
the
inner
cell
mass
give
rise
to
which
cells
at
the
egg‐cylinder
 stage?
 A)
Trophoblast
Giant
Cells.
B)
Epiblast
 C)
Extra‐embryonic
ectoderm
D)
Visceral
Endoderm
 
 42)
Which
of
the
following
describes
cleavage?
 A)
Mitotic
cell
division
without
cytokinesis.
 B)
Mitotic
cell
division
with
DNA
synthesis
and
growth
phases.
 C)
Mitotic
cell
division
without
DNA
synthesis
 D)
Mitotic
cell
division
lacking
any
growth
phases.
 
 43)
In
the
mouse
embryo,
the
descendents
of
animal
pole
blastomeres
at
the
4‐cell
stage
are
 located
at
the
embryonic
pole
of
the
blastocyst
and
the
anterior
pole
of
the
egg‐cylinder
stage
 embryos.
 A)
True
B)
False
 
 44)
To
study
the
role
of
Tead4
in
regulating
the
growth
or
differentiation
of
the
liver
you
would
 need
a:
Since
Tead4
mutants
won’t
survive,
you
need
a
way
to
mutate
the
gene
in
a
given
tissue
at
a
 particular
time.
 A)
conditional
knockout
B)
enhancer
trap
 C)
gene
trap
D)
knockout
 
 45)
If
the
trophectoderm
does
not
differentiate:
 A)
the
embryo
will
fail
to
implant
into
the
uterus.
 B)
the
inner
cell
mass
will
not
form
–
in
a
tead4
mutant
trophoblast
cells
do
not
form
and
all
the
cells
 are
inner
cell
mass
like.
 C)
the
fetus
will
not
grow
because
of
lack
of
nutrients.
The
embryo
can’t
grow,
because
it
can
never
 implants.
 D)
all
the
above
 
 46)
Cre‐recombinase
can
facilitate
recombination
between
two
LoxP
sites
and
result
in
the
deletion
 of
DNA
located
between
the
two
LoxP
sites.
 A)
True
B)
False
 
 47)
If
an
outer
blastomere
at
the
compacted
morula
stage
divides
orthoganol
to
the
cell's
axis
of
 polarity
(asymmetric
division):
 A)
both
daughter
cells
will
inherit
the
SCMC
and
differentiate
into
inner
cell
mass
cells.
 B)
one
daughter
cell
will
inherit
the
SCMC
and
differentiate
into
trophectoderm,
the
other
 will
become
an
inner
cell
mass
cell.
 C)
both
daughter
cells
inherit
the
SCMC
and
differentiate
into
trophectoderm
and
 extraembryonic
ectoderm.
 D)
one
daughter
cell
will
inherit
the
SCMC
and
differentiate
into
trophectoderm,
the
other
 will
become
extraembryonice
ectoderm.
 
 
 
 
 
 
 48)
In
which
period
of
human
development
is
the
embryo/fetus
most
susceptible
to
developing
a
 birth
defect?
 A)
The
fetal
period
(9‐38
weeks);
when
the
organs
of
the
fetus
functionally
mature.
Decreasing
 sensitivity
 B)
The
embryonic
period
(3‐8
weeks);
when
the
embryo
undergoes
gastrulation
and
 Organogenesis

 C)
The
pre‐embryonic
period
(1‐2
weeks);
when
the
embryo
undergoes
fertilization,
 cleavage
and
early
gastrulation
more
likely
to
recover
or
die
 D)
The
neonatal
period
(1st
two
years
after
birth);
when
the
brain
is
developing.
Birth
defect
is
at
 birth.
 
 49)
When
two
8‐16
cell
embryos
are
aggregated
together,
the
new
outer
cells
express
Cdx2
and
the
 inner
cells
express
Oct4;
which
of
the
following
scenarios
is
consistent
with
the
fate
of
the
 16‐cell
blastomeres
being
specified?
 A)
In
the
chimera,
all
cells
that
were
previously
on
the
outside
of
the
morula
sort
to
the
 outside,
while
cells
that
started
out
in
the
inside
remain
inside.
Determined
cant
change
fate
in
new
 environment
 B)
In
the
chimera,
cells
of
the
two
embryos
segregate
from
one
another,
resulting
in
the
 formation
of
twins.
Does
not
support
specified
 C)
In
the
chimera,
cells
located
on
the
outside
become
polarized,
regardless
of
whether
they
 had
previously
been
located
on
the
inside.
 D)
In
the
chimera,
cells
that
were
perviously
located
on
the
outside
that
are
now
on
the
 inside
undergo
apoptosis.
Determined
–
cant
change
fate
in
new
environment.
 
 50)
Overexpression
of
Oct4
inembryonic
stem
(ES)
cells
will
trigger
differentiation
of
primitive
 endoderm.
In
contrast,
decreasing
the
level
of
Oct4
expression
(1/2
normal
levels)
in
ES
cells
 triggers
differentiation
of
trophectoderm.
These
results
demonstrate
that
cell
differentiation
can
 be
influenced
by
the
dose
or
amount
of
transcription
factor
present
in
a
cell.
 A)
True
B)
False
 
 
 ...
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This note was uploaded on 09/29/2010 for the course BIO 325 taught by Professor Bernadette-holdener,g during the Fall '08 term at SUNY Stony Brook.

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