CELL CYCLE                               

CELL REPRODUCTION What are the three parts of the cell theory? Cell division-produce new cells from one cell Explain two reasons WHY cell division is required? Maintain proper surface-to-volume ratio Replace cells that die

CHROMOSOMES Structures that contain DNA Carries genetic material Exist as chromatin- long strands of DNA wrapped around proteins called histones Packs together before a cell divides

CHROMOSOMES

Growth in a Cell CELL CYLCE- sequence of growth & division in a cell. 2 general periods Growth-majority of a cell’s life Interphase- Division Mitosis- two daughter cells are formed

Interphase Cell performing duty in the tissue Growing DNA synthesis Copies chromosomes Prepares for cell division

Mitosis Occurs when maximum cell size is reached Four phases Prophase Metaphase Anaphase Telophase

PROPHASE 1ST phase & longest phase Chromatin coils into chromosomes Made up of 2 halves-sister chromatids Held together by a centromere

METAPHASE 2ND phase Double chromosomes attach to spindle fibers Lineup on the midline of cell

ANAPHASE 3RD phase Chromosomes separate and move to opposite sides of the cell.

TELOPHASE 4TH & final phase Chromatids reach opposite sides Chromosomes unwind Membrane begins to form Cytokinesis begins

CYTOKINESIS=Cell divides Plants Cell plate laid down Animals Plasma membrane pinches

                                                                                                                                            

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