1. Cell Division and Gene Expression The Need for Cell Reproduction - The Nature of Chromosomes - The Cell Cycle - Mitosis and Cytokinesis - Cancer Cells: Abnormal Cell Cycle The Expression of Genes as Proteins: DNA gene --> RNA --> Protein - Transcription by RNA Polymerase - The Three Types of RNA - Translation by Ribosome

2. What Cell Reproduction Accomplishes Reproduction –The birth of new organisms. –Occurs much more often at the cellular level Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings Cell division plays a role in –The replacement of lost or damaged cells. –Cell reproduction and growth.

3. Passing On Genes from Cell to Cell Before a parent cell divides, it duplicates its chromosomes. The two resulting “daughter” cells are genetically identical, each getting a duplicate set of chromosomes

4. Cell Division and Gene Expression The Need for Cell Reproduction - Copying Chromosomes - The Cell Cycle - Mitosis and Cytokinesis - Cancer Cells: Abnormal Cell Cycle The Expression of Genes as Proteins: DNA gene --> RNA --> Protein - Transcription by RNA Polymerase - The Three Types of RNA - Translation by Ribosome

5. Types of Reproduction Asexual reproduction –Single cells reproduce by mitosis –Two daughter cells produced from one parent cell Daughter cells are genetically identical to each other Daughter cells are genetically identical to the parent cell Sexual reproduction –Single or multi-celled organisms reproduce by meiosis –Four daughter cells called gametes (eggs and sperm) produced from one parent cell Gametes are genetically different from each other and parent cell Gametes must unite with other gametes of opposite type to produce viable organism –Use for growth and repair as well as producing new individuals –Finding a mate is unnecessary –Relatively “cheap” energetically –Used solely for making more individual single or multicellular organisms –A mate or a second organ for producing other gametes is required –Relatively “expensive” energetically; lower efficiency in producing offspring

6. Both Daughter Cells in Mitosis Must Get Chromosomes 12 chromosomes 12 chromosomes 12 chromosomes ? 12 + 12 chromosomes Duplication (Replication)

7. DNA Replication (Duplication) Occurs in S Phase of the Cell Cycle

8. Figure 3.32 Adenine Thymine Cytosine Guanine Old (template) strand Two new strands (leading and lagging) synthesized in opposite directions DNA polymerase Lagging strand Leading strand Free nucleotides Old strand acts as a template for synthesis of new strand Chromosome Helicase unwinds the double helix and exposes the bases Old DNA Replication fork DNA Replication is Performed by DNA Polymerase

9. Cell Division and Gene Expression The Need for Cell Reproduction - The Nature of Chromosomes - The Cell Cycle - Mitosis and Cytokinesis - Cancer Cells: Abnormal Cell Cycle The Expression of Genes as Proteins: DNA gene --> RNA --> Protein - Transcription by RNA Polymerase - The Three Types of RNA - Translation by Ribosome

10. The Cell Cycle G 1 Growth S Growth and DNA synthesis G 2 Growth and final preparations for division M G 2 checkpoint G 1 checkpoint (restriction point) >95% of the cells in your body are not progressing through the cell cycle and will never divide

11. Chromosomes Must Be Condensed or Packaged Before Cell Division DNA Packing

12. Cell Division and Gene Expression The Need for Cell Reproduction - The Nature of Chromosomes - The Cell Cycle - Mitosis and Cytokinesis - Cancer Cells: Abnormal Cell Cycle The Expression of Genes as Proteins: DNA gene --> RNA --> Protein - Transcription by RNA Polymerase - The Three Types of RNA - Translation by Ribosome

13. Mitosis Overview Prophase Metaphase Anaphase Telophase/ Cytokinesis Mitosis (All Phases) Animal Mitosis Sea Urchin (time lapse)

14. Figure 8.8.1 G 2 of Interphase: Chromosomes indistinct Centrosomes replicate Mitosis Overview To M Phase: 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase and Cytokinesis Late Interphase

15. Figure 8.8.2 1. Chromosomes condense, become visible 2. Nuclear membrane dissolves 3. Centrioles move to opposite poles, grow fibers 1. Chromosomes line up in a column 90 o to spindle Prophase Prometaphase Metaphase

16. 1. Sister chromatids separate and move towards opposite poles 2. Two nuclear membranes reform 3. Cell divides in half (cytokinesis) 1. Chromosomes unwind (decondense) AnaphaseTelophase

17. Cytokinesis –Typically occurs during telophase. –Involves contracting microfilaments Cytokinesis Cell Splitting in Telophase: Cytokinesis

18. Mitosis Overview Prophase Metaphase Anaphase Telophase/ Cytokinesis Mitosis (All Phases) Animal Mitosis Sea Urchin (time lapse)

19. Cell Division and Gene Expression The Need for Cell Reproduction - The Nature of Chromosomes - The Cell Cycle - Mitosis and Cytokinesis - Cancer Cells: Abnormal Cell Cycle The Expression of Genes as Proteins: DNA gene --> RNA --> Protein - Transcription by RNA Polymerase - The Three Types of RNA - Translation by Ribosome

20. Cancer Cells: Growing Out of Control Normal plant and animal cells have a cell cycle control system. Cancer is a disease of the cell cycle. Cancer cells do not respond normally to the cell cycle control system. Cancer cells can form tumors, –Abnormally growing masses of body cells. If a tumor is malignant and metastasizes it can spread to other parts of the body.

21. Figure 8.10 Breast Cancer

22. Cell Division and Gene Expression The Need for Cell Reproduction - The Nature of Chromosomes - The Cell Cycle - Mitosis and Cytokinesis - Cancer Cells: Abnormal Cell Cycle The Expression of Genes as Proteins: DNA gene --> RNA --> Protein - Transcription by RNA Polymerase - The Three Types of RNA - Translation by Ribosome

23. Central Dogma of Biology: How Shape and Form Are Dictated By DNA Genes A segment of DNA (gene) carries specific coded instructions for the making of a single proteins. Genotype: The genes carried in a cell for a particular trait Phenotype: The physical expression of genes for a particular trait

24. Figure 3.34 Nuclear pores mRNA Pre-mRNA RNA Processing Transcription Translation DNA Nuclear envelope Ribosome Polypeptide