1. Cell specialization

3. What TWO different things can the stem cell do?
Self-renewal
Differentiation

4. Why self-renew AND differentiate?
1 stem cell
Why self-renew AND differentiate?
1 stem cell
4 specialized cells
Self renewal – makes sure stem cells don’t run out
Differentiation - replaces dead or damaged
cells throughout your life
The stem cell is dividing along the way. At the end of the process, you still have 1 stem cell but 4 new specialized cells.
The key take-home messages are:
1) Self renewal is needed because if the stem cells didn’t copy themselves, you would quickly run out. It is important for the body to maintain a pool of stem cells to use throughout your life.
2) Differentiation is important because specialized cells are used up, damaged or die all the time during your life. Specialized cells cannot make copies of themselves, but they need to be replaced for your body to carry on working. Stem cells solve this problem. 4

5. What happens when you run out of stem cells
What happens when you run out of stem cells? What do you think would happen if your body ran out of blood stem cells?
You stop replenishing the damaged and dead cells in your body.

6. Where can I find Stem cells?
Adult Stem Cells Embryonic Stem Cells
We all have stem cells located throughout our bodies which we call Multi-potent stem cells or Adult Stem Cells .They develop into the different cell types within the tissue they are found in. They are essential for keeping us fit and healthy. They replace cells that are damaged or that have died.
Pluri-potent Stem cells also known as Embryonic stem cells are found in the initial stages of the embryo and are capable of forming an entire organism because they can specialize into any cell they want.

7. blastocyst - a very early embryo
Embryonic Stem Cells
Tissue stem cells
embryonic stem cells
blastocyst - a very early embryo
around cells
fetus, baby and all your life
This is a very early embryo – an extremely early stage of development of a baby, about 5 days after the sperm fertilizes the egg. It is a ball of 100 to 150 cells. They are found inside the blastocyst and they can make all the cells in the body. 7

8. Blood stem cells: A type of tissue stem cell
white blood cells
differentiation
differentiation
red blood cells
found in
bone marrow
Blood stem cells are found in your bone marrow. They are a type of tissue stem cell and they can make the different kinds of cells in your blood. We saw that earlier with the stem cell decision maker.
The answer is about 3 months (120 days). And white blood cells live for an even shorter time (different types have different life spans). That’s why your body needs to make new blood cells all the time.
How long do you think a red blood cell lives ? 8

9. Nearly 4 times around the earth’s equator
How hard are they working?
If you lined up all the red blood cells from your body, how far would they stretch?
Nearly 4 times around the earth’s equator
Set the class a challenge:
“So these blood stem cells are busy in your body making white and red blood cells all the time. It’s a pretty big job because you’ve got a lot of red blood cells. Now we’re going to see if we can take on a class challenge together: to figure out just how hard these cells have to work.”
“You’ve got a lot of red blood cells. Each one is really tiny – smaller than the head of pin. If you lined them all up end to end, how far do you think they would stretch?”
Take guesses. 9

10. Making red blood cells 1 second! To count to 2 million it would take…
We counted to 20 in…
2 seconds
2 days
3 seconds
3 days
4 seconds
5 days
5 seconds
6 days
6 seconds
7 days
To make 2 million red blood
cells it takes your body…
1 second!
It generally takes students 3 or 4 seconds to count to 20 if they are really focussed on doing it quickly. This will reveal how long it would take to count to 2 million if you carried on counting at that speed, without any breaks for breathing, eating, sleeping, going to the toilet etc.
‘To make 2 million red blood cells it takes your body…’
This helps illustrate how amazing it is that your body makes so many blood cells every second.
Students sometimes ask how many cells there are in your whole body. Your body has about 25,000,000,000,000 red blood cells.

11. Stem cells in plants
Meristematic cells: Undifferentiated plant tissue from which new cells are formed. They are found at the tip of a stem or roots.
The undifferentiated plant tissue from which new cells are formed, as that at the tip of a stem or roots.

13. Specialized Cells Shape of the cell contributes to its function
Cell of epidermis (skin cells): flat for good protection
Neurons (nerve cells): elongated for conducting messages throughout your body
Red blood cells: are suspended in your plasma to form a liquid tissue that transports oxygen throughout your body

14. Cell specialization lab
looking at how the shape of the cell contributes to its function
you will look at these specialized cells under the microscope
you will need to draw 4 different ones
name the cell
name the function
where is it located in your body
Review Activities
Workbook: page 20-23