1. CHAPTER 12 – THE CELL CYCLE

2. SCIENCE STARTER
Describe both the structure and function of chromosomes.
What are sister chromatids?
What are centromeres?
1. Chromosomes are a single long, double-stranded molecule of DNA wrapped around proteins.
They function in the replication, division, and distribution of DNA from one generation to the next.
The are two identical copies of a chromosome’s DNA.
The are where the chromatids of a chromosome are attached.

3. THINK-PAIR-SHARE
Brainstorm various ways to equally divide a pile of several-sized rubber bands amongst themselves. (Apply what you know about how a cell divides its genetic information to help them come up with the most efficient, even method for distributing the rubber bands.)
Share your method with your elbow partner and discuss how your method compares to the method of mitosis.
Be prepared to share with the class.

4. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
The cell cycle is a well-ordered
sequence of events in which a
cell duplicates its contents and
then divides in two.
Some cells go through repeated
cycles while others do not
(e.g. nerve cells)
Mitosis is just one portion of the cell cycle

5. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
The mitotic (M) phase includes
both mitosis and cytokinesis.
Mitosis – Nuclear Division
Cytokinesis – Division of Cytoplasm

6. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
Interphase – the non-dividing phase
90% of the cell cycle
Consists of 3 periods:
G1 phase
S phase
G2 phase

7. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
Interphase – the non-dividing phase
90% of the cell cycle
Consists of 3 periods:
G1 phase – First growth phase
S phase
G2 phase

8. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
Interphase – the non-dividing phase
90% of the cell cycle
Consists of 3 periods:
G1 phase – First growth phase
S phase – DNA replication
G2 phase

9. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
Interphase – the non-dividing phase
90% of the cell cycle
Consists of 3 periods:
G1 phase – First growth phase
S phase – DNA replication
G2 phase – Second growth phase

10. THE MITOTIC CELL CYCLE
The mitotic phase alternates with interphase in the cell cycle
At the end of interphase a G2 cell is
characterized by:
A well-defined nucleus bounded by a nuclear
envelope
Microtubules extend from the centrosomes
in radial arrays called asters
Centrosomes consist of a pair of centrioles
Duplicated chromosomes cannot be
distinguished individually due to loosely packed chromatin fibers

11. PROJECT
With a partner create a 3D model of two different chromosomes. You may construct the chromosome out of any materials that you find in the classroom. (You may also use your own materials.) The model must include sister chromatids, chromatin, and a centromere for each chromosome. The chromosome model will also need to be capable of demonstrating mitosis at a future time point.