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Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG. Image by Riedell. CELL GROWTH & DIVISION 10-1 & 10-2. Reasons why cells divide. DNA OVERLOAD. 1. _____________________ As cell grows bigger demand on DNA “genetic library” becomes too great.

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  1. Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG Image by Riedell CELL GROWTH & DIVISION 10-1 & 10-2

  2. Reasons why cells divide DNA OVERLOAD 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

  3. Reasons why cells divide Material exchange can’t keep up 2. _____________________As cell grows bigger demand for transport across membrane is too great http://www.animationlibrary.com

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

  5. Reasons why cells divide Image by Riedell 3.ToGrow-Multicellular organisms grow mainly by increasing cell number More cells, not bigger cells

  6. Now we know why cells divide, let’s talk about how • What do you think will have to happen before a cell can divide into identical copies? • What is the most important thing that needs to be copied?

  7. DNA CAN BE: SPREAD OUT INNON-DIVIDING CELLS SCRUNCHED UP IN DIVIDINGCELLS CHROMOSOMES CHROMATIN

  8. 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

  9. DNA in EUKARYOTES(Plants & Animals) • DNA is ROD-SHAPED CHROMOSOMES • MANY PAIRS • FOUND IN NUCLEUS http://cellbio.utmb.edu/cellbio/chrom2.jpg

  10. Chromosome structure CHROMATIDS • ___________________ 2 identical arms • __________________ constricted area holds chromatids together CENTROMERE HOMOLOGOUS • __________________ PAIR 2 of each chromosome(one from mom; one from dad)

  11. HOMOLOGOUS CHROMOSOMES • SAME SIZE • SAME SHAPE • CARRY GENES for the SAME TRAITS • BUT ______________! (Don’t have to have the SAME CHOICES) NOT IDENTICAL http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

  12. CFUWork alone on a separate sheet of paper. • Why do cells need to divide? • How is the DNA different in Prokaryotes vs. Eukaryotes? • How are Chromatids related to each other? • How are Homologous Chromosomes related to each other?

  13. Vocabulary • When a cell divides, its offspring are called Daughter Cells. • Why? Because that’s what they decided long ago. • No you can’t call them Son cells, it just doesn’t sound right.

  14. CELL DIVISION in PROKARYOTES BINARY FISSION Bacteria reproduce using __________________________________ • It’s fast • Simple • Produces Identical Offspring/No sex required! http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg

  15. What about Eukaryotes; You know, things with a nucleus? ______________ =series of events that cells go through as they grow and develop or more simply, A cell’s lifetime cells alive cell cycle CELL CYCLE

  16. CELL CYCLE INTERPHASE – non-dividing phase- Includes: G1- Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) G2- Grow bigger, copy organelles & molecules needed for cell division

  17. CELL DIVISION MITOSIS – Nuclear division in 4 stages 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase Cytokinesis – Final step, Cytoplasm divides You end up with 2 identical copies- very important!!!!

  18. Figure 10–4 The Cell Cycle Section 10-2 G1 phase M phase S phase G2 phase

  19. Cell Cycle Check for Understanding • What are the stages of the cell cycle? 2. Define mitosis: 3. In what phase does a cell spend most of its life? 4. In what phase does the DNA get copied?

  20. In between divisionsCells 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 INTERPHASE (G1 - S - G2)

  21. Pearson Education Inc publishing as Pearson Prentice Hall PROPHASE 1st dividing phase P= Preparing http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html 1. DNA scrunches into chromosomes 2. Centrioles appear 3. Nucleus disappears= DNA EXPOSED! 4. Spindle fibers form & attach to chromosomes

  22. Chromosomes line up in ___________ middle METAPHASE Images from:Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG

  23. Centromeres splitCentrioles pull chromatids_______ Apart ANAPHASE Images from:Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG

  24. two See ______ nuclei Nucleus returns but now there are two! TELOPHASE (reverse prophase steps) Chromosomes spread back out as chromatin and get back to work now that They are safe again. Images from:Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html

  25. CYTOKINESIS Cytoplasm splits into 2 cells ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW

  26. 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. CELL WALL CELL PLATE http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html

  27. Mitosis Check for Understanding • List the four stages of Mitosis in order • In what stage are copies (sister chromatids) pulled Apart from each other? • What is the name of the phase where the cell splits into two? • When mitosis is complete are the daughter cells identical to the parent cell?

  28. Videos Animal Cell Mitosis Animal Cell Cytokinesis

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

  30. M phase (Mitosis) Interphase G1 phase S phase G2 phase Prophase Metaphase Anaphase Telophase Concept Map Section 10-2 Cell Cycle includes is divided into is divided into

  31. Interest Grabber Answers Knowing When to Stop Suppose you had a paper cut on your finger. Although the cut may have bled and stung a little, after a few days, it will have disappeared, and your finger would be as good as new. 1. How do you think the body repairs an injury, such as a cut on a finger? The cut is repaired by the production of new cells through cell division. 2. How long do you think this repair process continues? Cell division continues until the cut is repaired. 3. What do you think causes the cells to stop the repair process? Students will likely say that when the cut is filled in, there is no room for more cells to grow.

  32. REGULATING the CELL CYCLE http://www.travel-net.com/~andrews/images/animations/traffic.gif

  33. Control of Cell Division Section 10-3 If center cells are removed,cells near the space will start to grow again. SHOWS: Cell division genes can be turned on and off Cells grow until they touch other cells

  34. EXAMPLE: Cell division genes can be ________ in case of injury. Cells near injury are stimulated to divide to heal and replacedamaged/missing cells and shut off when the repair has been made. CELL DIVISION GENES turned on

  35. Some cells divide frequently (some human skin cells divide once/hour) Some cells divide occasionally (liver cells divide about once/year) Some cells don’t divide once they form (nerve cells) CELL DIVISION GENES

  36. Molecules on the surface of neighboring cells act as signals to slow down or stop the cell’s cycle. These signals prevent excessive growth and keep tissues from disrupting each other. EXTERNAL REGULATORS Pearson Education Inc; Publishing as Pearson Prentice Hall

  37. Cancer cells have lost control of their cell division genes SEM Image by: Riedell CHO (Chinese Hamster Ovary) cells in culture

  38. Cancer cells don’t stop when they touch nearby cells. . . they just keep growing! That’s what makes a tumor. See a video NO CONTACT INHIBITION http://www.exn.ca/news/images/2000/08/02/20000802-cancer.jpg

  39. Cancer cells • Don’t stop dividing • Like a “car with no brakes” • Can spread to new places (METASTASIS) • ______________ are substances that can damage DNA and cause cancer Ex: Cigarette smoke (OR CHEW), Radiation, chemicals in environment, even viruses, Carcinogens http://www.dfci.harvard.edu/abo/news/publications/pop/fall-winter-2004/images/metastasis_1.jpg

  40. 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 can’t respond to normal cell signals to control their growth. CELL CYCLE p53

  41. Check For Understanding • What is contact inhibition? • What causes a healthy cell to replicate? • What is a Carcinogen? Give one example.

  42. ANTI-SMOKING commercial

  43. MEIOSIS11-4 http://waynesword.palomar.edu/lmexer2a.htm Making gametes…

  44. Interest Grabber 1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis? 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo? 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have? 46 chromosomes 46 + 46 = 92; a developing embryo would not survive if it contained 92 chromosomes. Sperm and egg should each have 23 chromosomes.

  45. Remember from Chapter 1:CHARACTERISTICS OF LIVING THINGSALL LIVING THINGS __________ REPRODUCE Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htmFamily http://babyhearing.org/Parenet2Parent/index.asp

  46. ASEXUAL REPRODUCTION http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html BINARY FISSION Bacteria reproduce using __________________________________ Budding & regeneration are used by plants and animals to reproduce asexually (mitosis) http://fig.cox.miami.edu/~cmallery/150/mitosis/c7.13.2.hydra.jpg Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm

  47. Single Celled Eukaryotes: EX: Yeast and Algae Two Unicellular Eukaryotes • Yeast and Algae are single celled or unicellular, but are still Eukaryotes • They reproduce from Mitosis only • How do their offspring (Daughter cells) compare to the parent cells? Bacteria or Prokaryote

  48. BINARY FISSION & MITOSISTwo types of Asexual Reproduction identical Produces cells that are __________ copies of parent cell

  49. ADVANTAGES OF ASEXUAL REPRODUCTION Can make offspring faster Don’t need a partner http://www.mrgrow.com/images/cutting.jpg

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