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Ms. He's Cell Division

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  • Only need one parent for asexual reproduction. Their offspring will have identical genetic materials Sexual reproduction needs two parents. Each parents cell will carry half the genetic information -> gametes. Two parental cells then join to form zygote which have complete genetic information,  different process (meiosis)
  • This causes limitations in communication when the cells gets too big.
  • Communication between nucleus and organelles & nucleus and other cells. **Take longer time for nucleus (control center) with --- Ex. nerve cells, they need to sent signals to other nerve cells.
  • Decreasing SA:V as cell increase the size
  • SA:V ratio decrease means cell membrane does not grow as fast as inside the cell (the volume) -> thus ….stretch the membrane and increase the cellular concentration
  • All cells need nutrients, water, and gas exchange (ex.oxygen,water, sugar). What are the process that brings in those nutrients and water????
  • As the eukaryotic cell grow and divide,
  • Transcript

    • 1. 1. Questioning and think-pair-share discussion2. Why do cells divide?3. Introduction to cell cycle4. Animation5. Homework: “Cell cycle on the Internet” handout
    • 2. What is a cell?the structural and functional units of all livingorganisms.Unicellular organismsingle-celled organism (ex. Bacteria)Multicellular organismany organism made up of more than one cell (ex.Human)
    • 3. Humans start out as one fertilized egg (a single cell). How does it grow into an organism with trillions of cells?
    • 4. Why do you think it is important for cells to divide? and why?
    • 5. 1. Reproduction2. Growth3. Repair
    • 6. At the end of lesson, you will understand that:All cells divide so that the organism canreproduce, grow, and repair itself
    • 7.  Reproduction: production of offspring from a parent cell or a combination of parent cells Single cellular organisms use cell division as a means of reproducing  Bacteria Some multicellular organisms also use cell division to produce offsprings:  Starfish, coral etc.  Plants, fungi
    • 8.  Asexual reproduction: one parent, offspring will have identical genetic copies Sexual reproduction: two parental cells containing half the genetic information (gamete) join to form an offspring new cell having a whole set of genetic information (zygote)  Human gamete: sperm and egg
    • 9.  Binary fission – daughter cells are the same size (e.g. bacteria) Budding – the bud is smaller than the parent (e.g. yeast) Fragmentation – a small part grows into a whole organism (e.g. starfish and coral) Vegetative propagation – plant puts out shoots or roots that grow into identical new plants (e.g. strawberry plant)
    • 10.  Occurs in single celled bacteria Cell division in prokaryote Daughter cells will be identical to the original parent
    • 11. Animations http://highered.mcgraw-hill.com/sites/983409233(first half)
    • 12.  Occurs in single celled yeast A small offspring will grow from the parent, and will eventually breaks off
    • 13.  A new organism grows from a part that breaks off of the parent
    • 14. http://krishisewa.com/articles/2011/imgs/sb01.jpg  Plants are identical clones connected together by a runnerhttp://www.morning-earth.org/graphic-e/biosphere/PLANTIMAGE/DISPERSAL/VEGPROP/strawberryrunners.jpg http://images.tutorvista.com/content/reproduction/vegetative-propagation-by-runners.jpeg
    • 15.  Why do multicellular organisms grow by producing more cells instead of just enlarging a couple of cells?  Why increase quantity instead of increasing volume?  Why more cells instead of bigger cells?
    • 16.  Larger multicellular organisms do not necessarily have larger cells but they do have more cells  More cells are needed to carryout different jobs  Cells specialize and differentiate to carryout specific functions ▪ Ex. Muscle cells for movement, white blood cells to fight infection…
    • 17.  Over a cells lifespan, the size of the nucleus grows very little while the rest of the cell continues to grow Yellow circle: nucleus Grey circle: cytoplasm
    • 18.  Over a cells lifespan, the size of the nucleus grows very little while the rest of the cell continues to grow Cell reaches a maximum size due to limitations in communication when the cell gets too big  3 types of communication is affected
    • 19.  Communication distance from nucleus 1. Nucleus to the rest of the cell (to organelles) 2. Nucleus to the cell membrane (to other cells) Yellow circle: nucleus Grey circle: cytoplasm
    • 20. Communication Restrictions for efficientbetween communicationNucleus and organelles Distance of nucleus to(and other cell parts) rest of cellNucleus and other cells Distance of nucleus to cell membraneCell processes to external Volume of cell to amountenvironment of cell membrane
    • 21.  Surface area to cell volume ratio Yellow circle: nucleus Grey circle: cytoplasm
    • 22. Surface area to cell volume ratiohttp://plaza.ufl.edu/alallen/pgl/modules/rio/stingarees/module/why.html
    • 23.  Assume our cell is a cubed shape Calculate the surface area and volume of the cell as the length of each side of the cell increases by 1 cm Plot both sets of data on the same graph Length of one side (cm) Surface area (cm2) Volume (cm3) 1 1 1 2 24 8 3 4 5 6 7 8
    • 24. The effect of increasing cell size on the surface area to volume ratio600 Total Volume (cm3)500 Total Surface Area (cm2)400300200100 0 0 1 2 3 4 5 6 7 8 Length of one side of the cube (cm)
    • 25. The effect of increasing cell size on the surface area to volume ratio600 Volume (cm3)500 Surface Area (cm2)400300200100 0 0 1 2 3 4 5 6 7 8 Length of one side of the cube (cm)
    • 26. The effect of increasing cell size on the surface area to volume ratio  What is the8000 effect of Volume (cm3)7000 Surface Area (cm2) increasing cell6000 size on the5000 surface area to4000 volume ratio?300020001000 0 0 2 4 6 8 10 12 14 16 18 20 Length of one side of the cube (cm)
    • 27. Communication Restrictions for efficientbetween communicationNucleus and organelles Distance of nucleus to(and other cell parts) rest of cellNucleus and other cells Distance of nucleus to cell membraneCell processes to external Volume of cell to amountenvironment of cell membrane
    • 28. The effect of increasing cell size on the surface area to volume ratio  Why is this8000 change in ratio Volume (cm3)7000 Surface Area (cm2) NOT beneficial6000 for a cell?5000  What types of4000 cellular3000 processes2000 prefer a high1000 surface area to volume ratio? 0 0 2 4 6 8 10 12 14 16 18 20 Length of one side of the cube (cm)
    • 29.  Diffusion: movement of substances across a membrane from an area of high  low concentration  Examples of cell usage of diffusion: ▪ Water product excretion ▪ Absorption of gases (e.g. oxygen) ▪ Absorption of chemicals and nutrients (e.g. sugar) Osmosis: movement of water across a membrane from an area of high water (low solute)  low water (high solute) concentration  Solute: a substance dissolved in another substance; the component of a solution present in the lesser amount
    • 30.  As a cell grows, the surface area to volume ratio decreases.  Limitations of communication ▪ Between nucleus (control center) and organelles ▪ Between nucleus and other cells ▪ Between cell and external environment
    • 31.  Maintenance: healing due to injury Normal replacement: due to cell lifespan  Each type of tissue has its own turnover time related to the workload endured by the cells  Most cells in our body are less than 10 years old http://www.timeshighereducation.co.uk/story.asp?storyCode=198208&sectioncode=26
    • 32. Cell Type LifespanLining of gut 5 days Skin 14 daysRed blood cell 120 days Liver cell 300-500 days Bone 10 years Neurons From birth
    • 33.  The cell cycle regulates how long a cell lives Sometimes cells die because they have suffered injury or damage that cannot be repaired
    • 34.  http://www.youtube.com/watch? v=rgLJrvoX_qo&feature=related
    • 35. InterphaseMitosis
    • 36.  Scientists have identified a repeating cycle of events in the life of a cell This cycle of events is called the cell cycle
    • 37. Every hour, about one billion (109) cells die andone billion cells are made in your body. Part ofthe cell cycle includes making new cells in aprocess called cell division.
    • 38.  The cell cycle has four phases:  G1 Phase  S Phase  G2 Phase  M Phase Interphase
    • 39.  The cell spends about 90% of its time in interphase
    • 40.  Composed of 3 phases: G1, S, G2 Often called the “resting” phase but cell is not at rest Cell is not dividing Cell is active:  taking in nutrients  Growing  conducting other normal cell functions http://student.ccbcmd.edu/~gkaiser/biotutorials/dna/mitosis/images/interphase1_pc.jpg