Transcript Cell and Embryo Developmentx

Ch 14.1-3
What do I want
to be when I
grow up??
Development
 1 cell changes into different forms
ANIMAL DEVELOPMENT:
EMBRYO
Fertilization of
Gametes
egg
Zygote
Blastula
(hollow ball of cells)
Gastrula
(gut forms)
Cells have
differentiated
Seed leaves
Plant Development
Pollen
Ovuole
GAMETES
ZYGOTE
EMBRYO
Steps of a Cell getting it’s job
1. Determination- its plan for a job

Ex. Mesenchymal Stem Cells become Connective Tissue
2. Differentiation- cell actually gets it’s job

Ex. Mesenchymal Stem Cells become Muscle, Fat, Tendon
(or other connective tissues)
3. Morphogenesis- change shape & cells find
their places!

Occurs by Cell Division, Apoptosis, & cell movements
4. Growth- Size of organs and body gets bigger
Cell Fate
 Cell Fate- what kind of cell it will become
 Blastula cells don’t have cell fate, they become
their surroundings
 Gastrula cells have their cell fate
Plant Cloning
 Dedifferentiate- carrot root cells (calli) could
lose jobs, and become entire new plants
 Genome Equivalence- all cells in a plant have a
full genome (and if treated right, can become
any cell in the organism)
 Great finding for agriculture
Animal Cloning
1. E-nucleate an egg
2. Give it a nucleus from the cell you want
3. Zap! Fuse egg/nucleus together
4. Transplant into Surrogate Mom’s uterus
5. Birth! Out pops a clone
What does this mean
for us!???
1. Clone for Food (GMO- Genetically Modified Organic Material)
2. Preserve Endangered Species
3. Clone Organs
4. Preserve your pet!
Adult Stem Cells
PLANTS:
 Meristems tips of roots/stems (undifferentiated &
divide quickly)

15-20 jobs
MAMMALS:
 in mostly all tissues, replace cells after apoptosis
or necrosis (cell death)

300 jobs
Types of Stem Cells
1.
Totipotent- cells that can become any part of a new organism
Zygote cells
A.
2.
Multipotent- become only a few types of cells
Adult Stem Cells
A.
1)
a.
b.
3.
Ex. Bone Marrow:
Hematopoietic stem cells  Red/White Cells
Mesenchymal stem cells  Bone/Muscle Cells
Pluripotent- can form most cells in the body
Embryonic Stem Cells
A.
A.
B.
C.
D.
Removed from Blastocyst
Less likely to be rejected than organ donation or Adult Stem Cells
Controversial--- Destroys the potential for life?
PROBLEM FREE: Induced Pluripotent Stem Cells (iPS cells)- skin cells that have
been turned into ESC
How Cells Differentiate
1. Cytoplasmic Segregation- empty cells have
different fates than the cells full of cytoplasmic
determinants
Polarity
2. Induction- fates determined by the cell’s location
and different signals (molecules called “inducers”)
1.
EX. LIN-3 inducer causes different signals that lead to
3 possible fates in a Nemotode Worm’s vulva
1.
2.
Can could be primary vulva precursor, Secondary vulva
precursor, or regular skin
Travels through signal transduction pathway
Apoptosis
 “cuts” out human fetal fingers
 Ex. Nematode Embyro1,090 cells  951 cells in
adult nematode
 Genes CED-4 and CED-5 expressed in apotosis
Day 35
Day 56
Organ Identity Genes
 Encode proteins that create different “whorl” or
flower parts groups (petals, sepals, stamens, carpels)
Each cell has same potential to turn
into blue, white, or red
1
2
3
4
5
6
Threshold for inducing “BLUE” fate
Concentration
of Morphogen
Threshold for inducing “RED” fate
1
1
2
2
3
3
4
4
5
5
6
6
Position value is
interpreted by the cells
and creates a pattern
Positional Information
 Position information stored in a Morphogen signal
 Travel to other groups of cells by diffusion
1
2
3
4
5
6
1
2
3
4
5
6
Other Genetic Cues
 Maternal Effect Genes- transcribed in mother’s
ovaries and determine the types of cells that will be
on the outside of the egg
 Ex. Concentrations of Bicoid and Nanos (MEG) cause
different effects
 Segementation Genes- cascades of genes that
lead to the cells that are apart of an insect’s
segments
 Hox Genes- tells head cells to make eyes, thorax
cells to make wings, etc