Somatic Cellular Reproduction: The Cell Cycle and Mitosis The Cell Cycle and Mitosis 1

Cells that make up the “body” of an organism 2

Why Should Cells Divide??? In Unicellular Organisms: Reproduction Reproduction In Multicellular Organisms: Maintain a favorable surface area to volume ratio Maintain a favorable surface area to volume ratio Maintain correct number of chromosomes Maintain correct number of chromosomes 3

Structures that contain the genetic material 4

Chromosomes are composed of chromatin, a tangled mass of DNA and proteins The Full Number of Chromosomes Found in all Somatic Cells is the Diploid Number (2N) The Diploid Number includes 2 of each chromosome (a pair) 5

Each Chromosome contains two identical parts called “sister chromatids” attached at a centromere 6

The cycle of growth and division in all cells Consists of Interphase and Mitosis Mitosis (M phase) is a period of cell division Interphase is a period of DNA replication and growth in preparation for cell division Interphase is a period of DNA replication and growth in preparation for cell division 7

The Cell Cycle Growth Protein Synthesis Cell Division DNA copies itself interphase mitosis 8

Growth and DNA synthesis and Replication (G 1, S, G 2 ) Longest period of Cell Cycle Chromatin in nucleus appears as mass of threadlike structures 8

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Chromatin Condensed Into Visible ChromosomesChromatin Condensed Into Visible Chromosomes Nucleolus Disappears and Nuclear Envelope FragmentsNucleolus Disappears and Nuclear Envelope Fragments Centrioles move to opposite sides of the cellCentrioles move to opposite sides of the cell 11

Chromosomes lined up on equatorial plateChromosomes lined up on equatorial plate Spindle fibers attach at centromeresSpindle fibers attach at centromeres 12

Centromeres divideCentromeres divide Sister chromatids pulled towards the polesSister chromatids pulled towards the poles 13

Spindles disappear and nuclear envelope returnsSpindles disappear and nuclear envelope returns Nucleolus returnsNucleolus returns Chromosomes unwind into chromatinChromosomes unwind into chromatin 14

Animal Cell Plant Cell 15

Identify the Stages of Mitosis