1. Cell Division and the Cell Cycle

3. The Cell Cycle Interphase Division Stage is the growth phase
makes new molecules that increase the cell volume
DNA is copied during this phase
consists of 3 parts, G1, G2 and S
Division Stage
consists of mitosis and cytokinesis

4. Stages of Growth Phase G1 S G2 gap 1
cell has rapid growth and carries out metabolic activity S
DNA is replicated G2
centrioles replicate
Cells are preparing to undergo division

5. Division Stage Shortest events in the cell cycle 2phases M phase
Mitosis
Division of the nucleus
Cytokinesis
Division of the cytoplasm

7. Prokaryotic Cell Division
Is usually through Binary Fission
Prokaryotic chromosome is a single DNA molecule that replicates , then attaches each copy to a different part of the cell membrane.
When cells pull apart the replicates chromosomes are separated.
Following separation there are two cell of identical genetic composition

9. Eukaryotic Cell Division
Mitosis
Meiosis
Cytokinesis
Roles
Before division can occur:
Organelles must be replicated and sorted.
DNA must be replicated and sorted.
Many chromosomes are involved.
Chromatin
Chromatids
Centromere
Mitotic chromosome
Histones
Homologues
Homologous chromosomes
Haploid (1N)
Diploid (2N)

10. What is the Function of Mitosis
Helps organism regenerate damaged tissues
Maintenance of the body
Replaces cell that don’t work or dead cells
Occurs in somatic or body cells
New cells are identical to the previous ones
Must maintain the same number of chromosomes from cell to cell

11. What happens during mitosis
During cell division the original parent cell divides to produce 2 new daughter cells
Mitosis ensures that daughter cells contain the same number of chromosomes and genetic information as the parent cell
Body cell contains 2 copies of every chromosomes
At this point the parent cell produces 2 identical daughter cells with 46 chromosomes
Before mitosis the parent has 46 chromosomes after mitosis the new daughter cells each have 46 chromosomes
Deals only with the segregation of the chromosomes and organelles into daughter cells
Animals cells have a centriole that aid in cell division

16. Cell Cycle and Mitosis Rate of cell cycle Varies with cell type
Hormones and growth factors regulate the rate.
Cancer
Interphase
Appearance of cell

18. Stages of Mitosis
Phases
Prophase, Metaphase, Anaphase, Telophase

19. Prophase First of four phases
Chromatin coils and condenses into Chromosomes
Each chromosome is made up of 2 sister chromatids held together by a centromere
Spindle fibres forms
Centrioles migrate to opposite poles
nuclear membrane dissolves,
nucleolus disappears

22. Metaphase Second phase
Spidnle fibers attach to the centromere of replicated chromosomes
Chromatids are guided to middle of the cell with the help of spindle fibers
Chromosomes line up in middle of the cell.

24. Anaphase Third Phase Centrosome splits apart
Spindle fibres help to pull apart sister chromatids.
These then move toward opposite spindle poles because the microtubules are shortening

26. Telo-phase Fourth and last phase Chromatids reach opposite poles.
At this point each chromatid is called a single non- replicated chromosome
Chromosomes unwind and become less visible.
Nuclear membrane forms around each set of chromosomes.
Spindle is dismantled and disappears.
Nucleolus reappears.
Two new cells identical to the parent cell
Opposite of prophase

28. Mitosis (pro-meta-ana; ciol up , line up, split up)

29. Cytokinesis Happens after mitosis.
It is the separation of the cytoplasm and the formation of 2 new daughter cells.
During cytokinesis the cytoplasm and all its contents divides between the two halves of the cell.
In animals: Cleavage furrow forms due to the contraction of the microfilaments of the cytoskeleton. Like a noose. Cells eventually pull apart into 2 identical cells.
In plants: A cell plate forms between the 2 new nuclei. This eventually forms a cell wall that separates 2 identical cells.

37. Mutations affecting cell division
A mutation is a permanent change in the DNA that can change the genetic information of a gene causing it to function improperly or not at all
Caused by chemical compounds, radiation, or specific viruses
After it has occurred it will be copied in subsequesnt cell division and passed to daughter cells
Found only in the two cell produced from that parent cell
Most are insignificant because they can be replaced by normal cells
If the mutation occurs in the gene that controls the cell division process it can result in cancer ( the uncontrolled rapid growth and division of cells)

40. Radiation Therapy and cell division
Involves directing radiation such as x-rays or gamma rays at the affected part of the body
Works by damaging the chromosomes in a cell rendering it unable to grow or divide
Healthy cells are damaged as well as cancerous cells but they can repair themselves
Used on tumours of the skin, breast, larynx and cervix
Side effects include skin inflammation, fatigue, sterility in males(testicular cancer)

41. Chemotherapy and Cell division
Includes a course of 1 or several types of drugs used in conjunction with radiation
Some drugs attack dividing cells as they divide while other prevent division
It affects the entire body because it is used to treat cancers that are spread throughput the body such as leukemia
Side effects include hair loss, nausea, or diarreha

42. Complete each of the following terms.
Chromatin Interphase Mutation
Chromatids Prophase Radiation
Centromere Metaphase Chemotherapy
Mitoitic chromosome Anaphase
Histones Cytokinesis Telophase
Homologues Cell Cycle
Homologous chromosomes G1
Haploid (1N) G2 Spindle fibres
Diploid (2N) S
Sister chromatids Daughter cells