1. Cell Growth and Division

2. Cell Growth Limits to growth Stress on DNA
Difficulty moving nutrients/wastes across membrane
Ratio of surface area to volume
Volume increases at a faster rate than surface area

3. Cell Division
Before a cell becomes too large, it divides, producing 2 daughter cells
Each daughter cell is an exact replica of the parent cell
DNA is replicated

4. Cell Division 2 stages (eukaryotes) Asexual reproduction
Mitosis- division of the cell nucleus
Cytokinesis- division of the cytoplasm
Asexual reproduction

5. Chromosomes
Threadlike structure within the nucleus containing the genetic information (DNA) that is passed from one generation of cells to the next
Cells of every organism have a specific number of chromosomes
Fruit flies = 8; Humans = 46; carrots = 18

6. Chromosomes
Chromatin- consists of DNA tightly coiled around proteins (nucleus)
Chromatid- one of two identical “sister” parts of a duplicated chromosome
Centromere- an area where the chromatids are attached to one another

9. The Cell Cycle
2 major phases
Interphase
Mitosis

10. Interphase 3 phases G1 phase= cells do most of their growing
S phase= chromosomes and DNA replicated
G2 phase= many of the organelles and molecules required for cell division are produced

11. Mitosis Divided into 4 phases Followed with Cytokinesis
Prophase
Metaphase
Anaphase
Telophase
Followed with Cytokinesis
Depending on cell- may last a few minutes to several days

12. Prophase 1st and longest phase of mitosis Events
Chromosomes become visible
Nucleolus disappears
Nuclear envelope breaks down

13. Metaphase Often lasts only a few minutes Events
Chromosomes line up across the center of the cell
Microtubules connect the centromere of each chromosome to the two poles of the spindle

14. Anaphase Sister chromatids separate and move to opposite poles
Anaphase ends when chromosomes stop moving

15. Telophase Nuclear envelope re-forms Spindle begins to break apart
Nucleolus becomes visible

16. Cytokinesis Animal cells: Plant cells: Result? 2 new identical cells
Cell membrane is drawn inward until the cytoplasm is pinched into 2 nearly equal parts
Plant cells:
Cell plate forms midway between the divided nuclei
Cell wall begins to appear in the cell plate
Result? 2 new identical cells

18. Controls on Cell Division
Cells stop growing when they come into contact with other cells
If cells are removed, the remaining cells will begin dividing again
Something can turn cell division on or off

19. Regulating Cell Growth
Cyclins- proteins that regulate the timing of the cell cycle in eukaryotic cells
Internal regulators: proteins that respond to events inside the cell
External regulators: proteins that respond to events outside the cell

20. Uncontrolled Cell Growth
Cancer- disorder in which some of the body’s own cells lose the ability to control growth
Cancer cells do not respond to the signals that regulate the growth of most cells