The Diversity of
Cellular Life
Chapter 7-4
I. Stem Cells
A. Unspecialized cells with potential to
differentiate(become specialized in structure
and function).
B. All the different types of tissue in your body (ex.
Blood, nerve, skin, heart, liver, muscle, hair) were
produced by mitosis from stem
cells.
II. Sources of Stem Cells
A. Human embryos
1. Very controversial
2. Raises many moral and ethical questions
B. Also found in:
1. Adult bone marrow
2. Umbilical cord blood cells.
C. Recently scientists have been able to
reverse the “clock” of skin cells and turn
them into stem cells.
D. One day we may be able to replace
damaged tissue with stem cells from our
own body!
III. Stem Cells in Medicine
A. Have the potential to:
1. Reverse brain and spinal injuries
2. Grow new liver tissue
3. Replace heart valves
4. Reverse effects of diabetes
How do cells become Specialized?
IV. It starts with fertilization of an egg cell by a
sperm cell which creates a zygotye (The
organisms first somatic cell).
The zygote will:
1. Make IDENTICAL copies of itself by mitosis
2. Become a ball of TOTIPOTENT cells (stem cells that
could separate from each other and produce a new
organism. Identical twins, triplets, etc.
3. As more cells are produced by mitosis, they will form a
BLASTOCYST, made of PLURIPOTENT stem cells.
V. Pluripotent(stem)cells
A. All have exactly the same DNA.
B. Have the POTENTIAL to become ANY TYPE OF CELL in the
organism!!
C. Can NOT become a brand new fetus, like Totipotent cells
can.
D. Once pluripotent cells differentiate or specialize into a
specific type of cell in the organism, they can not become
any other cell.
E. Can come from a blastocyst in an early developing fetus or
umbilical cord blood or bone marrow cells after birth!
Pluripotent cells have the potential to
treat disorders/conditions such as:
•
•
•
•
•
•
Spinal cord injuries
Parkinson’s
Diabetes
Amputations
Hemophilia
Serious skin injuries
VI. Cell Specialization
=DIFFERENTIATION
A. When a pluripotent cell turns into a specific
type of cell in the organism, it has
differentiated or specialized.
B. Cells in multi-cellular organisms become
SPECIALIZED by turning on genes needed for a
particular cell’s function and turning off genes
not necessary for that cell to function.
Nerve cell
Skin cell
Muscle cell
Stem or
Pluripotent cell
1. Red blood cells transport O2, and CO2
a. Protein called hemoglobin carries the
oxygen in the RBC.
b. So, RBC’s need genetic info for making
hemoglobin turned on.
• A Day in the Life of a Red Blood Cell
2. Cells in the pancreas produce proteins that
function as hormones and enzymes important
in the breakdown of food.
So, genes for making proteins like insulin need to
be turned on.
3. Striated muscle cells allow
movement
So, Genes necessary for proteins that
allow muscles to contract must be
turned on.
SPECIALIZED ANIMAL CELLS
Muscle cells
Cheek cells
Red blood cells
B. Specialized Plant Cells
1. Plants exchange carbon dioxide, oxygen, water
vapor, and other gases through tiny openings
called stomata on the undersides of leaves.
2. Highly specialized cells, known as guard cells,
regulate this exchange.
Specialized Plant cells
Guard cells
Xylem cells
Pollen
ATOMS
________
MOLECULES
__________
ORGANELLES
 ___________
CELLS
TISSUES
____________
 ____________
Similar cells
working together

ORGAN
ORGANS
SYSTEMS
___________  __________
Different tissues
working together
Different organs
working together
ORGANISM
___________
Levels of Organiation that are
LIVING/ALIVE
1.
2.
3.
4.
5.
Cells
Tissues
Organs
Organ Systems
Organism
http://www.youtube.com/watch?v
=jF2iXpoG5j8 3 min
https://www.youtube.com/watch?
v=evH0I7Coc54