Download Chapter 42 Review: Embryology and Stem Cells What are the three

Chapter 42 Review: Embryology and Stem Cells
1.
What are the three processes that allow a zygote to transform itself into an embryo?
Cell division(cleavage), cell migration and cell differentiation
2. Place the following stages of development in order: gastrula, organogenesis, zygote, blastula, morula,
blastopore formation
Zygote, morula, blastula, blastopore formation, gastrula, organogenesis
3. Which organ/organ systems would fail to develop if the endoderm did not form?
Lining of digestive and respiratory systems
4. Which organ/organ systems would fail to develop if the ectoderm did not form?
Skin and nervous system
5. Which organ/organ systems would fail to develop if the mesoderm did not form?
Skeletal, circulatory, and muscular systems
6. What type of cell division are cleavage divisions? mitotic
7. What happens to cell size as cleavage divisions occur? Decreases (no growth between divisions)
8. What happens to the embryo size as cleavage divisions occur? Remains unchanged (cells get smaller)
9. How is the cleavage division cycle different from the typical mitotic cell cycle?growth portion of interphase is
skipped
10. How does a morula become a blastula? Cells inside the morula migrate outward to hollow out the center
11. How does a blastula become a gastrula? Cells on one side of the blastula migrate into an area called the
blastopore creating an inner tissue layer called endoderm. Later cells migrate between the outer and inner
layers creating mesoderm (middle layer).
12. In what way are all the cells in your body similar? What makes them different? They all have the same DNA.
Different genes are expressed
13. Describe the two mechanisms that direct the developmental fate of embryonic cells? (Tell the cells where to go
and what to become.) Induction: chemical messages released from cells activate genes in neighboring cells
instructing them to migrate or differentiate. Gene Regulatory Substances originally in the egg cytoplasm are
distributed to daughter cells during cleavage divisions. These active or silence genes causing the cells to
migrate and differentiate.
14. Where do gene regulatory substances come from? How do they get distributed into the cells of the embryo?
The egg cytoplasm. Cleavage divisions
15. Identify the correct stage of development for each of the starfish embryos in the table below:
Embryo
Stage of Development
Embryo
Stage of Development
4 cell stage
Morula (solid ball of
cells)
Gastrula (early to mid)
 Dark streak is the cells
migrating into the
blastocoel.
 The inside of the streak
will become the
digestive tract. The cells
lining the streak become
the endoderm.
 The outer layer of cells
around the entire
gastrula is the ectoderm.
Eight cell stage (not all cells
visible)
Blastula (hollow ball of
cells)
 Lighter center is
the blastocoel;
the hollow
chamber inside
Late Gastrula
Ectoderm
Mesoderm
Endoderm
Late Blastula to early gastrula
The flat area on top is the
beginning of the blastopore.
Two cell stage
Stem Cell Review:
1. List the three types of stem cells you learned about. Somatic (adult), Induced Pluripotent, Embryonic
2. How are embryonic stem cells obtained? Removed from the inner cell mass during the blastocyst stage (57 days after fertilization)
3. How are induced pluripotent stem cells created?
A specialized cell from the patient is removed and exposed to chemicals that cause it to dedifferentiate.
These cells can then be programmed to develop into any needed cell type.
4. What do adult (somatic) stem cells do in an organism?allow for growth, tissue repair and maintenance
throughout the life of the organism
5. Complete the following table for the three types of stem cells
Feature
Embryonic Stem Cell
Induced Pluripotent
Stem Cell
Potential to become any X
X
cell type
Potential to become only
a limited range of cell
types
Ethical issues due to
X
destruction of an embryo
to obtain
Therapeutic use could
X
cause immune rejection
by the patient
Found in bone marrow
Adult (somatic) stem cell
X
X
Solid Ball of Cells
Hollow ball of cells
Fertilized egg
Morula
Mitotic cell division
with little or growth
inbetween
Blastula
Cell with the
potential to become
any cell type in the
body
Zygote
Indentation in the
blastula through
which cells migrate
during the beginning
stage of gastrulation
Cleavage
Stem Cell
Cavity inside the
blastula
Blastocoel
Blastopore
Process by which
Embryo with three
cells release chemical tissue layers
messages that
determine the
Gastrula
developmental fate
of neighboring cells
Induction
Process by which cell The term for a human Process by which
migration transforms blastula
cells take on
a blastula into a
specialized structures
gastrula
and functions
blastocyst
gastrulation
differentiation
Genes that direct the Stem cells obtained
development of
from a blastocyst
entire body
segments; arranged
Embryonic stem cells
Stem cells
responsible for
growth, repair and
maintence of tissues
“head to toe” on the
chromosome
throughout the life of
an organism
homeobox
Tissue layer that gives Tissue layer that gives
rise to the lining of
rise to the skin and
the digestive and
nervous system
respiratory tracts
ectoderm
endoderm
Somatic stem cells
Tissue layer that
gives rise to the
circulatory, skeletal
and muscular
systems.
mesoderm
Stem Cells produced
by reprogramming
specialized cells to
dedifferentiate
The development of
organs and organ
systems from the
three tissue layers
Induced Pluripotent
organogenesis