Module 2: Quizzes

Question 1

T/F Until the blastula stage, the cleavage stage embryo relies on maternally
deposited mRNA and proteins.

Answer 1

T

Question 2

T/F If action polymerization is blocked using a drug, cortical rotation will not occur
and therefore Nieuwkoop center is not formed.

Answer 2

T

Question 3

T/F Lithium blocks cortical rotation and blocks siamois expression

Answer 3

F
- Lithium inhibits GSK3

Question 4

T/F The normal fate of dorsal mesodermal cells is to differentiate into muscle and
notochord

Answer 4

T

Question 5

T/F Type I TGFb-receptor phosphorylates Smad 2/3

Answer 5

F

Type II must first phosphorylate Type I then Smad 2,3 can be phosphorylated

Question 6

T/F b-catenin and Vegt bind to the enhancer of nodal and control the gene
expression

Answer 6

T

Question 7

T/F GSK3 is the critical component that is transported to the dorsal side of frog
embryo after cortical rotation?

Answer 7

F

Question 8

In Xenopus, the mesoderm moves in through the blastopore by rolling around the dorsal lip. This process is called:_________________

Answer 8

Involution

Question 9

In Xenopus, the organizer mesodermal cells undergo intercalation and the tissue
elongates toward the anterior region. This process is called: _____________

Answer 9

Convergent Extention

Question 10

What is the name of the first visible structure that forms at the beginning of neurulation? _________________

Answer 10

Neural plate

Question 11

T/F: Notochord originates from the chordamesoderm and is the most anterior mesoderm structure in vertebrates

Answer 11

F

• It is the POSTERIOR

Question 12

Identify three factors that are secreted from the organizer.

Answer 12

BMP - ventralization
Noggin, Chordin, and Follistatin secreted dorsally to inhibit BMP

Question 13

Describe the common neural induction mechanism that is shared between Xenopus and Drosophila.

Answer 13

• BMP is like Dpp, Chordin is like Sog
• Lack of BMP/Dpp is required for neuralization
• Chordin and Sog secreted into neuroectoderm to create BMP/Dpp inhibition

Question 14

What molecules are emitted from the mesoderm to induce posterior neural tissues?

Answer 14

Wnt and retinoic acid

Question 15

____________ cells converge on the streak, and as it moves forward, prospective
mesoderm and endoderm cells move inward, spreading anteriorly and laterally, to form the ___________ layer

Answer 15

Epiblast, Mesenchymal

Question 16

The primitive streak of chick embryos is equivalent to which amphibian structure?

Answer 16

Blastopore

Question 17

The ___________ in the early chick embryo is a sheet of cells that give rise to
extraembryonic structures

Answer 17

Hypoblast

Question 18

How long does it take for a chick embryo to reach gastrulation? How many days does it take for a chicken embryo to hatch?

Answer 18

24 hours, 20 days

Question 19

Identify two secreted molecules that are expressed in Koller’s sickle.

Answer 19

Vg1 and Wnt

Question 20

Answer 20

A

Question 21

T/F: Presomitic mesoderm forms between the regressing Hensen’s node and the last
formed somite.

Answer 21

T

Question 22

T/F: Presomitic mesoderm acquires an anteroposterior positional identity before somite formation.

Answer 22

T

Question 23

T/F: If an extra piece of notochord is transplanted into a dorsal position adjacent to pre-somitic mesoderm, the somite will be converted almost entirely to muscle-forming cells

Answer 23

F

• it will become an induced axis

Question 24

The dermomyotome gives rise to two important structures. What are they?
________________ and ____________

Answer 24

Dermis and myotome

Question 25

When does the mediolateral patterning of somites occur in development?
a) Before neurulation
b) During neurulation
c) After neurulation

Answer 25

C

Question 26

Name a signal that is emitted by notochord and affects sclerotome development.
____________

Answer 26

Sonic hedgehog

Question 27

What molecules are involved in segregating each rhombomere to avoid cell mixing?
_______________ and ________________

Answer 27

ephrin, EPH

Question 28

Where do you initially see the primitive streak in the mouse embryo? What does it do?

Answer 28

• Beginning of Gastrulation
• Forms Epiblast
  
  • signals start of gastrulation
• Starts at caudal and moves anteriorly making notochord

Question 29

What is a blastocyst?

Answer 29

-Structure formed in early mammal embryogenesis
- Consist of two cell types; inner cell mass and trophectoderm (outer layer cells)

Question 30

What day does a blastocyst form in mice?

Answer 30

Day 3.5

Question 31

In mouse embryos, which of the following tissue will give rise to the embryo proper?
a) epiblast
b) inner cell mass
c) primitive endoderm
d) a and b
e) a, b and c

Answer 31

D
- Both Epiblast and inner cell mass result in the embryo proper (Blue on chart)

Question 32

Cite two reasons why you wish to insert a drug resistant gene in the exon of a gene you
wish to knockout in ES cells

Answer 32

1. inactivate target gene where drug selectable marker is inserted
2. enable selection of cells that have corrected DNA insertion

Question 33

T/F. Most people with situs inversus have no medical symptoms or complications

Answer 33

F

Question 34

T/F. Asymmetric activity of a proton potassium ATPase pump is one of the earliest signs
of LR asymmetry in chick.

Answer 34

T

Question 35

T/F In mammals, motile cilia produce a leftward flow of extraembryonic fluid and
eventually, this results in increasing Nodal production on the left.

Answer 35

T

Question 36

How would you identify patients with situs abnormality?

Answer 36

radiography, ultrasound,CT scan

Question 37

T/F. The general cell movement during gastrulation is similar in avian and human

Answer 37

T

Question 38

T/F. If a single embryo is transferred, yet two embryos have implanted in the uterus, it can be assumed to be a case of monozygotic twins.

Answer 38

T

Question 39

During the 5th day of human development, you are expected to see 1) ICM, 2) hypoblast,
3) epiblast, 4) primitive streak.

Answer 39

ICM