1. CELL DIVISION
TOPIC 2.5

2. ASSESSMENT STATEMENTS
Outline the stages in the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis
State that tumors (cancers) are the result of uncontrolled cell division and that these can occur in any organ or tissue
State that interphase is an active period in the life of a cell when many metabolic reactions occur, including protein synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplasts

3. Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase, and telophase)
Explain how mitosis produces two genetically identical nuclei
State that growth, embryonic, development, tissue repair and asexual reproduction involve mitosis

4. Topic 2.5 Exercise
Create a foldable which outlines the stages of the cell cycle, including interphase, mitosis, and cytokinesis
Must include name, description, and illustration for each phase of each stage

5. The cell cycle Describes the behavior of cells as they grow and divide
Produced cells are called daughter cells
Sometimes cells divide so rapidly without restraint that they form a solid mass of cells called a tumor (cancer)
Cancer can occur in any organ or tissue

7. Interphase Largest part of the cell cycle Phases
G1 – growth of the cell
S – replication of the DNA (synthesis)
G2 – growth of the cell, preparation for mitosis, increase in organelle number, DNA condenses from chromatin to chromosomes

9. Chromatin to chromosome
Chromatin condenses through a process called supercoiling
DNA wraps around histones to produce nucleosomes
Nucleosomes wrap into a solenoid
Solenoids group together in looped domains
Final coiling produces chromosome
Before replication in the S phase chromosomes are composed of one molecule of DNA
After replication the chromosome contains two molecules of DNA
These 2 molecules called sister chromatids are held together by centromere

11. Mitosis
When all preparations are made and the DNA has replicated, the cell moves into mitosis or the M phase
Four phases:
Prophase
Metaphase
Anaphase
Telophase

12. Prophase
Chromatin fibers become more tightly coiled to form chromosomes
Nuclear envelope disintegrates and nucleoli dissappear
Mitotic spindle forms
Centromere of each chromosome has a central region called the kinetochore that attaches to the spindle
Centrosomes move toward opposite poles of the cell due to lengthening microtubules

14. Metaphase
Chromosomes move to middle or equator of cell (metaphase plate)
Chromosome’s centromeres lie on the plate
Movement of chromosome is due to the action of the spindle which is made of microtubules
Centrosomes now at opposite poles

16. Anaphase Two sister chromatids of each chromosome are split
Chromatids move towards opposite poles of the cell
Chromatid movement due to shortening of microtubules
Since the centromeres are attached to the microtubules, they move toward the poles first
Each pole has a complete, identical set of chromosomes

18. Telophase Chromosomes are at each pole
Nuclear membrane (envelope) begins to reform around each set of chromosomes
Chromosomes begin to elongate to form chromatin
Nucleoli reappear
Spindle disappears
Cell is elongated and ready for cytokinesis

20. Cytokinesis In animals In plants
Inward pinching of the fluid plasma membrane to form cleavage furrows
In plants
Forms a cell plate which moves outward toward the sides of the cell from a central region
Both results in two separate daughter cells that have genetically identical nuclei

22. Activities which require involve mitosis
Growth
Embryonic development
Tissue repair
Asexual reproduction