2. FERTILIZATION
Fertilization is the fusion of the
haploid sperm cell nucleus
with the haploid egg cell
nucleus to produce a diploid
zygote (fertilized egg).
The process of fertilization
activates the egg, triggering the
beginning of embryonic
development.
The first of many challenges
3. CELL DIFFERENTIATION
Multicellular organisms begin
as undifferentiated masses of
cells called stem cells.
Variation in DNA expression
and gene activity determine
the differentiation of cells and
ultimately their specialization.
Differentiation is the process by which cells become
specialized. During the development of an organism,
cells differentiate into many types of cells.
4. CELL DIFFERENTIATION
All cells contain the same DNA so cells initially have the
potential to become any type of cell. When a cell becomes
specialized, only specific parts of DNA are activated; the
activated DNA determine the function and structure of a
cell.
A differentiated cell has become, quite literally, different
from the embryonic cell that produced it, and specialized to
perform certain tasks, such as contraction, photosynthesis,
or protection.
At some point the adult cell reaches the point at which
5. EMBRYOLOGY – COMMON ANCESTOR
Look at generation I.
What similarities
exist?
All these embryos
have so much in
common because
they all come from a
common ancestor.
Look at generation
III. Which organism
Editor's Notes
Our bodies, and the bodies of all multicellular organisms, contain highly differentiated cells that carry out the jobs we need to perform to stay alive.
As an analogy, think of the newborn child growing up. As he/she grows they learn. As they learn they realize they are to become a doctor, and they specialize their education geared to that end. Specialists are experts on how best to treat specific parts of the human body.
