1. The Cell Cycle
Chapter 2, Lesson 1

2. Big questions for something so small!
You start life as a single cell!!
You will have a trillion cells!!
SO . . .
How are all these cells made?
How long does a cell live?

3. The Cell cycle Cell cycle = the life cycle of a cell
Just like all living things, our CELLS have a cycle of life.

4. Draw Figure 1 from page 88 in your notebook. Use Color
Left Side
Draw Figure 1 from page 88 in your notebook.
Use Color
Predict: How long does it take to make a new cell? Explain.

5. Length of Cell Cycle Different for different cells.
Humans may have as many as 500 different types of cells in your bodies.
Skin cells = new cells every 24 hours
Liver cells = 1 year or more
Brain = never makes new cells, you get one chance.
Most our cells are like skin and take 24 hours

6. Left Length of Cell Cycle
Other organisms have cycles that are shorter
Zebra Fish:
From 1 cell to hatching in 48 hours.
Sea Urchin
From 1 cell to 4 in 2 hours.

7. Left Side Length of cell cycle
Describe: Describe the zebra fish or the sea urchin.
Predict: Why do different kinds of organisms’ cells have different cell lengths?
Talk with your partner and compare your answers.

8. We will know begin the Cell Cycle
Main Phases of cell cycle
Interphase Birth/Childhood
Mitosis Teenager
Cytokinesis Leaving your parents

9. Beginning the Cell Cycle
Interphase

10. First is Interphase When a cell is getting ready to reproduce
The longest phase.
The chromosomes in the nucleus look like a bunch of thin spaghetti because they are getting ready to be copied.

11. The Phases of Interphase
To summarize look at TB pg 91
Now what do you think Interphase does? Talk with a partner.
Answer
Growth and regular cell functions.
NUCLEUS makes chromatids
Organelles make copies of themselves.

12. The Phases of Interphase
Do ALL cells go finish interphase?
Answer:
Muscles, nerve, brain. Injuries to these can be permanent. The cells don’t leave interphase.
Drugs literally kill brain cells You can’t get them back once they have been damaged.

13. Time for a
Vocabulary lesson

14. DNA vs. Chromosomes What is DNA? What is a chromosome?
A macro molecule that makes proteins.
What is a chromosome?
DNA tightly coiled around some proteins into a smaller package. Humans have 46 chromosomes.

15. What is a homologous chromosome?
From mom
Homologous chromosomes are the matched set.
From dad
You get one from mom and one from dad. So we have 23 pairs of homologous chromosomes. /

16. What is a chromatid? Chromatid: copy of chromosome
Centromere: a region near middle of each chromatid that holds together each sister chromatid

17. Left Predict: Why do we need chromatids?
Predict: Why do we need centromeres?
Talk with your partner.
Answer:
The cell needs to make copies of EVERY chromosome so the new cell has EVERY chromosome.
Centromeres hold the copy to the original for a while.

18. For tomorrow More about this later.
But what are some things you notice?

19. Now we move on the to . . .
Mitosis

20. Different cells at different times
Four main phases
Prophase
Metaphase
Anaphase
Telephase 1
What phase is this?
Anaphase
How do we know?
The chromosomes are not lined up in the center or all the way at the ends.

21. Name the Phase and defend3 1 2 4
1 = Metaphase
4 = Interphase
2 = Telophase
3 = Prophase

22. Now to the end of the cycle
Cytokinesis

23. Cytokinesis The final stage Cytoplasm divides Organelles divide up
Occurs very quickly – like you “splitting” off this campus on a Friday.

24. The results of cell division
NO parent cell exists anymore!
The TWO daughter cells are identical!