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Chapter 12 Biology. Cell Division Allows unicellular organisms to reproduce Growth and Repair of multicellular organisms.

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Presentation on theme: "Chapter 12 Biology. Cell Division Allows unicellular organisms to reproduce Growth and Repair of multicellular organisms."— Presentation transcript:

1 Chapter 12 Biology

2 Cell Division Allows unicellular organisms to reproduce Growth and Repair of multicellular organisms.

3 How Prokaryotic Cells Divide Prokaryotic cells lack a nucleus and other membranous organelles. Divide by Binary Fission

4 Chromosome Is Singular Prokaryotic chromosome contains mostly DNA and some associated proteins Asexual reproduction requires a single parent; offspring are genetically identical to parent.




8 Eukaryotic Chromosomes and the Cell Cycle Karyokinesis – nuclear division Cytokinesis – division of the cytoplasm

9 A.Chromosomes Histone proteins organize chromosomes. Each species has a characteristic number of chromosomes.

10 A.Chromosomes a.Diploid (2n) number includes two sets of chromosomes of each type. b.Haploid (n) number contains one of each kind of chromosome.

11 A.Chromosomes Sister chromatids are two parts of a chromosome Centromere---a region of constriction on a chromosome





16 Mitosis Centrosomes –responsible for organizing the spindle. –main microtubule organizing center of the cell


18 Mitosis The centrosome has divided before mitosis begins. Each centrosome contains a pair of barrel-shaped organelles called centrioles; plant cells lack centrioles.


20 Mitosis Diagram

21 B.How Animal Cells Divide 1.Mitosis: –Interphase –Prophase –Pro-metaphase –Metaphase –Anaphase –Telophase.

22 Mitosis Movie


24 B.How Animal Cells Divide Prophase a.Chromatin condenses and chromosomes become visible. b.Nucleolus disappears and the nuclear envelope fragments. c.Short microtubules radiate out from the pair of centrioles located in each centrosome; form starlike asters.


26 B.How Animal Cells Divide Prometaphase a.attachment of chromosomes to the spindle and movement as they align at the metaphase plate (equator).


28 B.How Animal Cells Divide Metaphase a.Chromosomes align at the metaphase plate.


30 B.How Animal Cells Divide Anaphase a.Two sister chromatids of each duplicated chromosome separate at centromere. b.Daughter chromosomes, each with a centromere and single chromatid, move to opposite poles.


32 B.How Animal Cells Divide Telophase a.Spindle disappears. b.Chromosomes decondense and return to chromatin; the nuclear envelope reforms and nucleoli reappear. c.Cytokinesis is nearly complete.


34 Cytokinesis in Animal Cells a.Cleavage furrow indents the plasma membrane between the two daughter nuclei at a midpoint; progressively divides cytoplasm during cell division.



37 Mitosis Video

38 C.How Plant Cells Divide 1.Plant meristematic tissue in tips of roots and shoots 2.Stages are same as in animal cells. 3.Plant cells - no centrioles, and asters do not form.








46 Cytokinesis in Plant Cells Golgi apparatus produces vesicles that move to the midpoint between the daughter cell nuclei Vesicles fuse, forming a cell plate


48 How the Cycle is Controlled 1.Some cells divide continuously 2.Other cells are arrested in at different stages



51 Mitosis Stages

52 How the Cycle is Controlled 4.Enzymes known as cyclin-dependent kinases (Cdks) regulate passage of cells through these checkpoints


54 How the Cycle is Controlled Oncogenes (cancer-causing genes) may code for cyclins that no longer function as they should.

55 Cancer Cells


57 Cancer Radiation


59 Cancer Histroy




63 Cancer Causes

64 Cancer Angiogenesis the formation of new blood vessels. Malignancy and Metastasis ability to move and movment of cancer cells to a new location.

65 Cancer Treatment

66 Cancer Genetics

67 The End.


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