Image from: http://www.bcps.org/offices/lis/models/life/images/grow.jpg CELL GROWTH & DIVISION 10-1 & 10-2 Image by Riedell
2 Reasons why cells divide 1. DNA OVERLOAD 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 http://www.adc.state.az.us/images/off-library.jpg
2 Reasons why cells divide 2. Material exchange can t keep up As cell grows bigger demand for transport across membrane is too great http://www.animationlibrary.com
Ability to transport of oxygen, food, waste across cell membrane depends on SURFACE AREA Need for these depends on CELL VOLUME As cell grows these DON T increase at the same rate See relationship between volume and SA
Ratio of Surface Area to Volume in Cells Section 10-1 Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume Go to Section:
BIGGER CELLS NEED MORE FOOD and OXYGEN, but CAN T TRANSPORT IT FAST ENOUGH or IN BIG ENOUGH QUANTITIES! http://www.animationlibrary.com
Image from: http://www.bcps.org/offices/lis/models/life/images/grow.jpg Image by Riedell Multicellular organisms grow mainly by increasing cell number
DNA CAN BE: SPREAD OUT IN NON-DIVIDING CELLS CHROMATIN SCRUNCHED UP IN DIVIDING CELLS CHROMOSOMES
DNA in PROKARYOTES NO NUCLEUS HAVE ONE CHROMOSOME ATTACHED TO CELL MEMBRANE IN THE REGION NUCLEOID MANY BACTERIA CONTAIN A PLASMID WHICH IS A CIRCULAR DNA MOLECULE THAT REPLICATES SEPARATELY FROM THE CHROMOSOME. http://www.origin-life.gr.jp/3202/3202121/fig6.jpg
DNA in EUKARYOTES (Plants & Animals) DNA is ROD-SHAPED CHROMOSOMES MANY PAIRS FOUND IN NUCLEUS HUMANS HAVE 46 CHROMOSOMES, 23 PRS http://cellbio.utmb.edu/cellbio/chrom2.jpg
Chromosome structure 2 identical arms CHROMATIDS CENTROMERE constricted area holds chromatids together HOMOLOGOUS PAIR 2 of each chromosome (one from mom; one from dad)
HOMOLOGOUS CHROMOSOMES SAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT NOT! IDENTICAL (Don t have to have the SAME CHOICES) http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm http://sps.k12.ar.us/massengale/genetics%20tutorial.htm
CELL DIVISION in PROKARYOTES Bacteria reproduce using asexual BINARY FISSION reproduction called http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg
CELL CYCLE = series of events that cells go through as they grow and develop cells alive cell cycle
CELL CYCLE INTERPHASE non-dividing phase G 1 - Grow bigger Cell is doing its job DNA is spread out as chromatin S - Synthesis (copy DNA) & chromosomal proteins G 2 - Grow bigger, make organelles & molecules needed for cell division
CELL DIVISION MITOSIS Nuclear division Prophase Metaphase Anaphase Telophase CYTOKINESIS - Cytoplasm divides G 0 cell stops dividing (Ex: nerve cell)
Figure 10 4 The Cell Cycle Section 10-2 G 1 phase M phase S phase G 2 phase Go to Section:
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 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 DNA scrunches into chromosomes http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html Centrioles appear in centrosome region & move to poles Nuclear membrane & nucleolus disappear Spindle fibers form & attach to chromosomes (paired chromatids)
CENTROSOME region organizes spindle aster centrosome Microtubule (spindle fibers) centrioles Spindle MICROTUBULES are part of cytoskeleton http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm
METAPHASE Chromosomes line up in middle Hint: Count chromosomes by counting the centromeres 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 Centrioles pull chromatids apart 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) See two nuclei 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 growing a CELL PLATE down the middle. http://www.eastcentral.edu/acad/depts/bi/plant_mitosis_nolabels.html
Figure 10 5 Mitosis and Cytokinesis Section 10-2 Centrioles Spindle forming Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Spindle Centriole Nuclear envelope reforming Cytokinesis Telophase Anaphase Individual chromosomes Centriole Metaphase Go to Section:
Figure 10 5 Mitosis and Cytokinesis Section 10-2 Centrioles Spindle forming Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Spindle Centriole Nuclear envelope reforming Cytokinesis Telophase Anaphase Individual chromosomes Centriole Metaphase Go to Section:
Figure 10 5 Mitosis and Cytokinesis Section 10-2 Centrioles Spindle forming Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Spindle Centriole Nuclear envelope reforming Cytokinesis Telophase Anaphase Individual chromosomes Centriole Metaphase Go to Section:
Figure 10 5 Mitosis and Cytokinesis Section 10-2 Centrioles Spindle forming Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Spindle Centriole Nuclear envelope reforming Cytokinesis Telophase Anaphase Individual chromosomes Centriole Metaphase Go to Section:
Figure 10 5 Mitosis and Cytokinesis Section 10-2 Centrioles Spindle forming Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Spindle Centriole Nuclear envelope reforming Cytokinesis Telophase Anaphase Individual chromosomes Centriole Metaphase Go to Section:
Figure 10 5 Mitosis and Cytokinesis Section 10-2 Centrioles Spindle forming Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Spindle Centriole Nuclear envelope reforming Cytokinesis Telophase Anaphase Individual chromosomes Centriole Metaphase Go to Section:
Videos Animal Cell Mitosis Animal Cell Cytokinesis
Concept Map Section 10-2 Cell Cycle includes is divided into is divided into Go to Section:
Concept Map Section 10-2 Cell Cycle includes Interphase M phase (Mitosis) is divided into is divided into G 1 phase S phase G 2 phase Prophase Metaphase Anaphase Telophase Go to Section: