1. Written Response #9?
Cell Cycle - Handout

2. Mitosis Foldable

3. Understanding Mitosis
Prophase
(1st phase of mitosis)
Chromatin condenses to form visible chromosomes
1 chromosome = 2 sister chromatids
(packaged copies of DNA from S-phase of interphase)
Nuclear envelope disappears
Important structures for completion of the cell cycle appear:
Centrioles: send out spindle fibers
Spindle Fibers: attach to sister chromatids to pull apart
Centromeres: hold 2 sister chromatids together

4. Understanding Mitosis
Metaphase
(“M” is for Middle)
Chromosomes move to the middle of the cell
Still paired as sister chromatids
Attached in center with a centromere (also to spindles)

5. Understanding Mitosis
Anaphase
(“A” is for Apart)
Centromeres break and sister chromatids pull apart
Spindle fibers shorten and pull chromatids (now each is an individual chromosome) toward opposite sides of cell

6. Understanding Mitosis
Telophase
Begins when chromosomes reach opposite poles of cell
Chromosomes de-condense to less visible chromatin and nuclear envelope and organelles re-appear
Cell begins to pull apart and prepares for division

7. Understanding Mitosis
Cytokinesis
Animal Cells – cleavage furrow forms
Cell membrane pinches in to divide cells
Plant Cells – cell plate
Forms a new portion of the cell wall

8. How Do I Remember All of This?
1. Prophase – Hands together with fingers locked.
2. Prometaphase – Fingers wiggle.
3. Metaphase – Fingers overlapping facing each other.
4. Anaphase – Tips of fingers touching.
5. Telophase – Fist touching each other.
6. Cytokinesis – Separate fist.

9. Understanding Mitosis
Cell Cycle Regulation
Uncontrolled cell division results in tumors / cancer
Chemicals monitor each phase of the cycle
Reasons why cells may divide uncontrollably:
Radiation, carcinogens, mutated genes