Transcript CELL CYCLE
THE CELLULAR BASIS OF INHERITANCE CHAPTER 9 Why Is Cell Reproduction Essential for Life? #1) Maintain/Heal the Body – TO REPLACE LOST OR DAMAGED CELLS Example: Every minute of the day we lose about 30,000 to 40,000 dead skin cells off the surface of our skin. Why Is Cell Reproduction Essential for Life? #2) GROWTH - Increase body size by increasing the number of cells in the body Why Is Cell Reproduction Essential for Life? #3) REPRODUCTION = TO CREATE A COMPLETE NEW ORGANISM. 2 TYPES OF REPRODUCTION: a) ASEXUAL b) SEXUAL ASEXUAL REPRODUCTION How Many Parents? • SINGLE PARENT • OFFSPRING ARE GENETICALLY IDENTICAL TO EACH OTHER AND TO PARENT. • SEEN IN UNICELLULAR ORGANISMS AND SOME MULTICELLULAR ORGANISMS SUCH AS PLANTS,FUNGI, AND SOME ANIMALS LIKE SPONGES AND STARFISH. SEXUAL REPRODUCTION • 2 PARENTS • GENETIC MATERIAL (CARRIED IN EGG AND SPERM) FROM EACH PARENT COMBINES • EACH OFFSPRING IS GENETICALLY DIFFERENT FROM PARENTS • Egg and Sperm are produced through cell division REVIEW: WHY DO CELLS DIVIDE AND PRODUCE NEW CELLS? For Maintenance of the body (multicellular organisms) For Growth (multicellular organisms) For Reproduction (multi- and unicellular organisms) The “CELL CYCLE” • STARTS WHEN A CELL IS “BORN” & ENDS WHEN IT REPRODUCES. • CELL CYCLE PRODUCES CELLS NEEDED FOR GROWTH & MAINTENANCE OF THE BODY The “CELL CYCLE” Cell is not dividing (Most of the time) Cell is dividing Nucleus divides first Cytoplasm divides last The “CELL CYCLE” • HAS 2 MAIN STAGES: •INTERPHASE – cell isn’t dividing •MITOTIC PHASE – cell is dividing INTERPHASE •WHAT IS IT? •WHAT HAPPENS DURING IT? INTERPHASE • LONGEST STAGE (90% OF THE CELL CYCLE) • THE CELL GROWS & PERFORMS ITS JOB AS A CELL INTERPHASE • IN THIS STAGE DNA EXISTS AS A MASS OF VERY LONG THIN FIBERS CALLED CHROMATIN _________________. INTERPHASE • CELL ALSO PREPARES TO REPRODUCE (CELL DIVISION) BY INCREASING ITS NUMBER OF ORGANELLES & BY MAKING COPIES OF ALL DNA ITS _____________. muy importante!!! •EACH DNA STRAND IS COPIED & THE 2 COPIES ARE CENTROMERE JOINED AT ONE SPOT CALLED THE __________________. DNA IN CHROMATIN FORM What Happens Next?! •After the cell has made all its preparations, then it divides! •On to the Mitotic Phase!! MITOTIC PHASE • SHORTEST STAGE of the CELL CYCLE • THIS IS WHERE 1 CELL DIVIDES INTO 2 CELLS • OCCURS IN 2 STEPS: 1) MITOSIS 2) CYTOKINESIS MITOSIS • All about the Nucleus! • In this stage the nucleus divides into 2 and the chromosomes are evenly divided up. • Each daughter nucleus receives a complete set of chromosomes MITOSIS • ALL THE DUPLICATED CHROMATIN FIBERS NOW COIL UP (GET SHORTER & THICKER) & ARE CALLED CHROMOSOMES . ____________________ • EACH CHROMOSOME IS MADE UP OF 2 IDENTICAL HALVES SISTER CALLED ______________ CHROMATIDS . SISTER CHROMATIDS MITOSIS • The SISTER CHROMATIDS SEPARATE & GO TO OPPOSITE ENDS OF THE CELL FORMING 2 NEW “DAUGHTER” NUCLEI CYTOKINESIS • The CYTOPLASM DIVIDES BETWEEN THE 2 NEW “DAUGHTER” NUCLEI FORMING 2 NEW CELLS The “CELL CYCLE” Cell is not dividing (Most of INTERPHASE the time) Cell is MITOTIC dividing PHASE Nucleus divides first MITOSIS Cytoplasm divides last CYTOKINESIS Name the Structure! ? Centromere ? Centromere ? ? ? ? Chromosomes SISTER CHROMATIDS ? CELL CYCLE ______________ = series of events that cells go through as they grow and develop cells alive cell cycle CELL CYCLE INTERPHASE – non-dividing phase G1- Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) & chromosomal proteins G2- Grow bigger, make organelles & molecules needed for cell division CELL DIVISION MITOSIS – Nuclear division Prophase Metaphase Anaphase Telophase Cytokinesis – Cytoplasm divides G0 – cell stops dividing (Ex: nerve cell) INTERPHASE (G1 - S - G2) In between divisions Cells are in this phase most of the time Can see nucleus DNA spread out as chromatin Can’t see chromosomes DNA gets copied (S) Cell gets ready to divide Pearson Education Inc publishing as Pearson Prentice Hall PROPHASE 1st dividing phase http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html DNA scrunches into chromosomes Centrioles appear in centrosome region & move to poles Nuclear membrane & nucleolus disappear Spindle fibers form & attach to chromosomes CENTROSOME ________ region organizes spindle Spindle MICROTUBULES are part of cytoskeleton http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm METAPHASE Chromosomes line up in middle ___________ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG ANAPHASE Centromeres split apart Centrioles pull chromatids_______ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG TELOPHASE (reverse prophase steps) two nuclei See ______ Nuclear membrane & nucleolus return Chromosomes spread out as chromatin Centrioles disappear Spindle fibers disappear Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html CYTOKINESIS Cytoplasm splits into 2 cells ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ____________ CELL WALL Plant cells separate cytoplasm by CELL PLATE growing a _______________ down the middle. http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase Section 10-2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Metaphase