1. Suppose that your hand was made of one cell.
What would happen if that cell were to die?

2. Warm-Up Questions
After you’ve answered them, talk with the person sitting next to you!
What happens if a cell in our hand dies? Do all the cells die? Do we lose our hand?
How many cells are really in our bodies?
What does our body do to replace these dead cells? What is this process called?
Trillions

3. Cellular Reproduction

4. Review: why are cells small?
What was that ratio we talked about? What’s good, big or small SA:V? Transport.

5. How does this apply to cell division?
Once a cell reaches its size limit, it must divide.
This is also the way the cell reproduces!
Growth
Repair (of injuries)
Each time a cell goes through the cell cycle, it becomes two cells.
Today: Mitosis (Asexual Reproduction)
Friday: Meiosis (Sexual Reproduction)

6. The Cell Cycle Three stages
Interphase – cell growth/development, replication of DNA, preparation for division
90% of time spent here!
Mitosis – nucleus and nuclear material (chromosomes) divide
Cytokinesis – cytoplasm divides
Prokaryotes divide by binary fission
As few as 8 minutes, up to a year. Typically hours in us.
Binary fission – we’ll come back to this.

8. Phases of Interphase
Gap 1 (G1) – cell is growing and preparing for division.
immediately after the cell divides
Some cells exit and do not divide again
Synthesis (S) – cell copies its DNA for division
Chromosomes – structures that pass on genetic material
Chromatin – relaxed form of DNA in nucleus
Gap 2 (G2) – cell prepares for nuclear division
Checkpoint
Start here for 1st period!
Muscle and nerve cells.

9. Prophase Chromatin condenses into chromosomes
Terminology – Sister Chromatids
Centromere
Nuclear membrane disintegrates/Nucleolus disappears
Spindle apparatus of microtubules begins to form (Centrioles)
Mitosis – give me an example
Busiest stage. What does it mean to condense? (we can see shaped like an X)
Nucleolus disappears
Spindle apparatus include microtubules! Centrioles/aster fibers.

10. Metaphase
Sister chromatids are pulled by motor proteins along the spindle apparatus towards the center of the cell
Short stage
Metaphase plate

11. Metaphase

12. Anaphase
Sister chromatids are pulled apart via shortening of microtubules
Centromeres
Chromatids are moved towards the poles of the cells with the help of motor proteins

13. Anaphase

14. Telophase Chromosomes arrive at the end of the cell and de-condense
Nuclear membrane reforms/nucleolus reppears
Spindle apparatus disassembles
Nucleolus reappears

15. Cytokinesis Division of the cytoplasm – results in two cells
Microfilaments pinch the cytoplasm
Plant cells – cell plate forms

17. “Normal” Cell Cycle
Proteins called cyclins bind to CDKs (cyclin-dependent kinases) to proceed with various activities of the cell cycle.
Used as quality control checkpoints
That we talked about before

18. Cancer Cancer – uncontrolled growth and division of cells
Failure to regulate cell cycle
Due to mutations—changes in the DNA
Carcinogens – substances that are known to cause cancer
Why might risk of cancer increase with age?
Because the longer you live, the more likely you are to have a mutation

19. Apoptosis Programmed cell death – a controlled process
Fingers and toes
Leaves falling
What other reasons would cells have for doing this?
Stopped here! Remind them to think about reasons why cells would stop dividing…

20. Stem Cells
Unspecialized cells that develop under the “right” conditions
Embryonic stem cells – cells after fertilization before specialization
“Adult” stem cells – used for repair

21. Human Mitosis Dance - maybe
Groups of 7 (assigned by Mr. Koons)
One narrator
Parts that must be represented (by people, props, narration, etc.):
All four stages of mitosis plus interphase
Chromosomes (in various forms)
Centrioles/mitotic spindle
Centromeres
Nuclear envelope
Tell Mr. Koons your song choice!
We’ll assume you’re in a cell…

22. Before You Present Articulate Roles Clarify any props
Anything else you’d like to share