Stages of the Cell cycle

The Life of a Cell An organized sequence of growing until it divides One cell divided into 2 “daughter cells”

Why Divide? Single celled organisms For multicellular organisms For reproduction For multicellular organisms For development from fertilized egg to adult For growth and repair

Cell Cycle 2 major periods: Interphase Cell division Period of growth in-between divisions Cell division Period during which cell splits in 2

Interphase – Part I G1 Phase Period of growth Cell increases in size Cell makes new proteins and organelles

Interphase – Part II S Phase Synthesis of DNA molecules Chromosomes replicated

Interphase – Part III G2 Phase Preparation for cell division Organelles and molecules necessary for division are produced

Cell in Interphase

On to the next part…

Cell Division The period of cell division is also called M Phase 2 major periods: Mitosis Process of cell’s nucleus dividing Cytokinesis Process of entire cell dividing

M Phase - Mitosis 4 major periods Prophase Metaphase Anaphase Telophase

M Phase – Mitosis – Part I Prophase Chromatin begins to condense into chromosomes Centrioles separate on opposite sides of nucleus Spindle fibers form and approach centromeres Nuclear envelope breaks down

M Phase – Mitosis – Part I Prophase

M Phase – Mitosis – Part II Metaphase Spindle fibers attach to each chromosome at the kinetochore Chromosomes line up across center of cell

M Phase – Mitosis – Part II Metaphase

M Phase – Mitosis – Part III Anaphase Sister chromatids split and are pulled apart by spindle toward opposite ends

M Phase – Mitosis – Part III Anaphase

M Phase – Mitosis – Part IV Telophase Chromosomes begin to untangle back into chromatin Nuclear envelope reforms around each cluster of genetic material Spindle breaks apart

M Phase – Mitosis – Part IV Telophase

M Phase – Cytokinesis Cell membrane drawn in until cytoplasm pinched into 2 equal parts

M Phase – Cytokinesis Animal cells: contractile ring pinches cell membrane forming cleavage furrow

M Phase – Cytokinesis Plant cells: cytoplasm divided by cell plate which develops into cell membrane and cell wall

Put it all Together…