1. The Cell Cycle

2. Cell Division: Key Terms
Somatic cells (body cells)
Gametes (reproductive cells): sperm and egg cells
Genome: cell’s genetic information
Chromosomes: DNA molecules
Diploid (2n): 2 sets of chromosomes
Haploid (1n): 1 set of chromosomes
Chromatin: DNA-protein complex
Chromatids: replicated strands of a chromosome
Centromere: narrowing “waist” of sister chromatids

3. General info.
~ 10 trillion cells in body all from one cell by mitosis.
Erythrocytes (RBC) made one million per second
Cell division (mitosis)
Single celled = more individuals
Multi-celled = growth, differentiation and repair.
2 basic function
Duplicate the cell
Ensure daughter cell has complete copy DNA
The basic steps are
Duplicate the DNA
Divide the chromosomes into two complete sets
Divide the cell into two daughter cells
Same for Prokaryotes and Eukaryotes

4. The Cell Cycle http://www.sinauer.com/cooper/4e/animations1601.html
Cell Life Cycle.
Stages of Cell Growth
Interphase (90% of cycle)
G1 phase: primary growth phase. Cell does its 'job'.
S phase: DNA replication
G2 phase: Chromosome condensation, cell organelle replication
Mitotic phase
M phase: mitosis (nuclear division)
C phase: cytokinesis (cytoplasmic division)
daughter cells form

5. Mitosis Prophase Prometaphase Metaphase Anaphase Telophase

6. Prophase Pairs of Chromosomes (sister chromatids) visible
Nucleoli disappear
Mitotic spindle forms
Centrosomes (centrioles) move

7. Prometaphase Nuclear membrane fragments
Spindle fibers interaction with chromosomes
Kinetochore develops

8. Metaphase Chromatid pairs meet in the Middle of the cell
Centrosomes at opposite poles
Kinetochores of sister chromatids attached to microtubules (spindle)

9. Anaphase Sister chromatids come Apart
Chromosomes move to opposite poles
Each pole now has a complete set of chromosomes

10. Telophase Cytokinesis occurs forming Two new cells
Daughter nuclei form
Nuclear envelopes arise
Chromatin becomes less coiled
Two new nuclei complete mitosis

11. Cytokinesis Cytoplasmic division Animals: cleavage furrow
Plants: cell plate

12.
Cell Cycle regulation
Growth factors
Cyclins control the cell cycle , causing movement from G1 to S or G2 to M
Cdk (cyclin dependent kinase) work with cyclins
MPF (Maturation Promoting Factor) includes CdK and cyclins
p53 blocks cell cycle if DNA is damaged.
Density-dependent inhibition
crowded cells stop dividing
Anchorage dependence
to divide cells must be attached to a substrate or tissue matrix

13. Cancer http://www.hhmi.org/biointeractive/media/angiogenesis-lg.mov
Uncontrolled, rapid cell division
Cancer cells:
ignore cell cycle regulation signals
break away and settle in other parts of the body (metastasis)
don’t maintain function
consume lots of resources
Mutagens that change genes cause cancer (Carcinogens)
Oncogenes turn on cell division normally silent if moved they become active
Cancer cells are believed to be immortal.
Tumor: benign (harmless) or malignant (harmful)

14. Differentiation http://www.pbs.org/wgbh/nova/sciencenow/3209/04.html
Specialization and division of labor.
Pre-differentiation are stem cells
Totipotency: ability of a cell to divide and produce all the differentiated cells in an organism
Each cell has all the instructions (DNA) to produce a whole human
Nearby cells and/or the external environment triggers differentiation
Ensures efficiency in multicellular organisms
Groups of cells differentiate to form tissues and organs