CELL GROWTH & DIVISION 8-2 Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG CELL GROWTH & DIVISION 8-2 Image by Riedell

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 http://www.adc.state.az.us/images/Off-Library.JPG

2 Reasons why cells divide 2. _____________________ As cell grows bigger demand for transport across membrane is too great http://www.animationlibrary.com

Need for these depends on ___________ Ability to transport of oxygen, food, waste across cell membrane depends on _______________ Need for these depends on ___________ As cell grows these DON’T increase at the same rate

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

BIGGER CELLS NEED MORE FOOD and OXYGEN, but CAN’T TRANSPORT IT FAST ENOUGH or IN BIG ENOUGH QUANTITIES! http://www.animationlibrary.com

mainly by increasing cell number 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 SCRUNCHED UP IN DIVIDING CELLS

DNA in PROKARYOTES BACTERIAL DNA is CIRCULAR HAVE ONE CHROMOSOME NO NUCLEUS; ATTACHED TO CELL MEMBRANE 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 http://cellbio.utmb.edu/cellbio/chrom2.jpg

Chromosome structure ___________________ 2 identical arms constricted area holds chromatids together __________________ PAIR 2 of each chromosome (one from mom; one from dad)

HOMOLOGOUS CHROMOSOMES SAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT ______________! (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 __________________________________ http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg

______________ = 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) Can’t see chromosomes 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

PROPHASE 1st dividing phase DNA scrunches into chromosomes 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

___________ region organizes spindle CENTROSOME Spindle MICROTUBULES are part of cytoskeleton http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm

METAPHASE Chromosomes line up in ___________ 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_______ 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 ______ 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 ______________________

CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ____________ Plant cells separate cytoplasm by growing a _______________ down the middle. http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html

Figure 10–5 Mitosis and Cytokinesis Section 10-2 Spindle forming Centrioles Chromatin Centromere Nuclear envelope Centriole Chromosomes (paired chromatids) Interphase Prophase Spindle Cytokinesis Centriole Metaphase Telophase Individual chromosomes Anaphase Nuclear envelope reforming

Videos Click a hyperlink to choose a video. Animal Cell Mitosis Animal Cell Cytokinesis

Concept Map Cell Cycle Section 10-2 includes is divided into