CELL GROWTH & DIVISION 10-1 & 10-2 Pre-assessment Quiz Cell Growth and Division Limits to Cell Growth 1.DNA Overload 2.Exchanging Materials 3.Ratio of Surface Area to Volume 4.Cell Division 2 Reasons why cells divide 1. _____________________ As cell grows bigger demand on DNA genetic library becomes too great Ex: Small town library has 1000 books. As town grows and more people borrow books, there may be a waiting list to read the most popular titles DNA OVERLOAD 2 Reasons why cells divide 2. _____________________ As cell grows bigger, it gets harder to transport stuff across membranes Material exchange cant keep up The ability to transport of oxygen, food, waste across cell membrane depends on _______________ How much of this stuff used depends on ___________ SURFACE AREA CELL VOLUME As cell grows these DONT increase at the same rate, volume increases faster than surface area When cells get too big, they cant transport stuff fast enough, or in big enough amounts.So cells grow by dividing into many, small cells instead of growing few, bigger cells. 102Cell Division A. Chromosomes B. The Cell Cycle C. Events of the Cell Cycle D. Mitosis 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase E. Cytokinesis SPREAD OUT IN NON-DIVIDING CELLS SCRUNCHED UP IN DIVIDING CELLS CHROMATIN CHROMOSOMES DNA CAN BE: DNA in PROKARYOTES (Bacteria) BACTERIAL DNA is CIRCULAR HAVE ONE CHROMOSOME NO NUCLEUS; ATTACHED TO CELL MEMBRANE DNA in EUKARYOTES (Plants & Animals) DNA is ROD-SHAPED CHROMOSOMES MANY PAIRS FOUND IN NUCLEUS All organisms have specific numbers of chromosomes Humans = _____ Chromosomes Fruit Flies = 8 Chromosomes Carrots = 18 Chromosomes Chromosomes (scrunched up DNA) 46 Chromosome structure ___________________ 2 identical arms __________________ area that holds the chromatids together __________________ PAIR A pair of chromosomes (2) (one from mom; one from dad) CHROMATIDS CENTROMERE HOMOLOGOUS HOMOLOGOUS CHROMOSOMESSAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT _________________! Both have the same gene, but they dont have to be the same trait expressed Ex. Eye color might not have the same color of eyesNOT IDENTICAL CELL DIVISION in PROKARYOTES Bacteria reproduce using __________________________________ BINARY FISSION Cell Cycle Interphase G 1 S G 2 Mitosis (M) phase Prophase Metaphase Anaphase Telophase Cytokinesis CELL CYCLE in between division G 1 - Gap phase 1, Cell Growth Cell Growth, increase size Cell is doing its job DNA is spread out as chromatin S Synthesis phase Chromosomes are copied G 2 - Gap phase 2, Prepare for Mitosis Cell growth, get ready for cell division by producing organelles & molecules INTERPHASE CELL DIVISION Nucleus divides Prophase Metaphase Anaphase Telophase Cytokinesis Cytoplasm divides G 0 cell stops dividing (Ex: nerve cell) MITOSIS INTERPHASE (G 1 - S - G 2 ) In between divisions Cells are in this phase most of the time Can see nucleus DNA spread out as chromatin Cant see chromosomes DNA gets copied (S) Cell gets ready to divide PROPHASE 1st dividing phase Chromosomes appear (scrunched up X shape) Centrioles appear in & move to opposite poles of the nucleus Spindle fibers form & attach to chromosomes to help them separate Nuclear membrane & nucleolus disappear Pearson Education Inc publishing as Pearson Prentice Hall METAPHASE Chromosomes line up in ___________ middle Images from: Pearson Eduction Ince; Publishing as Pearson Prentice HallMicrotubules connect the centromere to the two poles of the spindle ANAPHASE Centromeres split and the centrioles pull the two sister chromatids _______ Anaphase ends when the movement stops apart Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall TELOPHASE See ______ nuclei Nuclear envelope & nucleolus return Chromosomes spread back out as chromatin Centrioles disappear Spindle fibers break and disappear two Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall CYTOKINESIS Cytoplasm splits into 2 cells ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS cant pinch because they have a sturdy ____________ Plant cells separate cytoplasm by growing a _______________ down the middle. CELL PLATE CELL WALL Cell Cycle Video 24/the-cell-cycle-mitosis/24/the-cell-cycle-mitosis/ Animation 2:nih1/cancer/activities/activity2_animations.ht mnih1/cancer/activities/activity2_animations.ht m includes is divided into Concept Map Section 10-2 Cell Cycle includes is divided into Concept Map Section 10-2 Cell Cycle M phase (Mitosis) Interphase G 1 phaseS phaseProphaseG 2 phaseMetaphaseTelophaseAnaphase REGULATING the CELL CYCLE Regulating the Cell Cycle Controls on Cell Division Cell Cycle Regulators 1.Internal Regulators 2.External Regulators Uncontrolled Cell Growth Controls of Cell Division Cells in a petri dish will continue to grow until they touch other cells. Cells in our bodies will do the same thing. Ex. A finger that stops bleeding. CELL DIVISION GENES Some cells divide frequently (some human skin cells divide once/hour) Some cells divide occasionally (liver cells divide about once/year) Some cells dont divide once they form (nerve cells) In early 1980s scientists discovered a protein in dividing cells that caused a ______________to form in _______________ cells CELL CYCLE REGULATORS Mitotic spindle NON-dividing Pearson Education Inc; Publishing as Pearson Prentice Hall Levels of this protein rose and fell with the cell cycle so it was named __________ because it seemed to control the cell cycle. A whole family of CYCLINS have since been discovered that regulate the _____________________ in EUKARYOTIC CELLS CELL CYCLE REGULATORS CYCLIN TIMING of CELL CYCLE Pearson Education Inc; Publishing as Pearson Prentice Hall ______________ REGULATORS Proteins that respond to events inside the cell. They allow cell cycle to proceed only if certain processes have happened EX: Cell cant enter mitosis until all the chromosomes have been copied OTHER REGULATORS INTERNAL ______________ REGULATORS Proteins that respond to events outside the cell. Signals tell cell to speed up or slow down the cell cycle EX: Growth factors stimulate cells to divide. Especially important during wound healing and embryo development OTHER REGULATORS EXTERNAL Molecules on the surface of neighboring cells act as signals to slow down or stop the cells cycle. These signals prevent excessive growth and keep tissues from disrupting each other. EXTERNAL REGULATORS Pearson Education Inc; Publishing as Pearson Prentice Hall Cancer cells have lost control of their cell division genes they dont stop growing when they touch nearby cells... they just keep growing! Thats what makes a tumor. NO CONTACT INHIBITION Cancer cells Dont stop dividing Like a car with no brakes Can spread to new places by entering the bloodstream (METASTASIS) ______________ are substances that can damage DNA and cause cancer Ex: Cigarette smoke (OR CHEW), Radiation, chemicals in environment, even viruses, Carcinogens Cancer cells Cancer is complicated and can have many causes, but all cancers have one thing in common. They have lost control over their _____________. Many cancers cells have a damaged or defective gene called _____, so they cant respond to normal cell signals to control their growth. CELL CYCLE p53 Cancer Animation 1:h1/cancer/activities/activity2_animations.htmh1/cancer/activities/activity2_animations.htm ANTI-SMOKING commercial