Transcript Do Now
Do Now 1. What happens to your body when you get a cut? 2. Make a drawing illustrating the healing process. Cellular Division Objectives 1. To understand why cells divide. 2. To explain different limitations on cell size. 3. To summarize the steps of the cell cycle. Cell Size *Take a look at the following cells… *Which cell do you think will work most efficiently? Surface Area vs. Volume L x W x # of sides LxWxH Practice… Find the SA:V ratio for the three cubes above. Which cube has the higher SA:V ratio? Size Limitations Key factor that limits cell growth is ratio of surface area to volume As the cell grows, its volume increases much more rapidly than the surface area. Cell can have difficulty supplying nutrients and expelling waste products. Transport of Substances Substances enter membrane through diffusion Diffusion over a large distance = slow Smaller cells are more efficient! Cell Communication The need for signaling proteins to move throughout the cell also limits cell size. Cell size affects the ability of the cell to communicate instructions for cellular functions. Cell Cycle Varies between 8 minutes and one year Average 12-24 hours Cell Cycle All cells start out in Interphase They then enter cell division, Mitosis & Cytokinesis Interphase A. G1 Phase: First growth phase The cell is growing, carrying out normal cell functions, and preparing to replicate DNA. B. S Phase: DNA is copied (DNA Replication) C. G2 Phase: Second Growth Phase Proteins needed for cell division are produced The cell prepares for the division of its nucleus. Mitosis/Cytokinesis Mitosis: Nuclear Division Cytokinesis: Cell Division Do Now Do Now Please hand homework in the bin. Grab a piece of construction paper from my desk. (Color doesn’t matter) Then sign into Kahoot.it using the game code on the board. This will be done individually. Important Vocab. Chromosome Tightly coiled DNA Chromatid Half a replicated Chromosome Chromatin loosely coiled DNA Centromere Center of a chromosome where the sister chromatids attach Centriole Organize the microtubules Attach to the spindle fibers MITOSIS Prophase Nucleolus disappears Nuclear membrane breaks apart The cell’s chromatin tightens making chromosomes visible! Sister chromatids are attached at the centromere. Spindle apparatus forms and attaches to centromeres of chromosomes. Metaphase Sister chromatids (duplicted chromosomes) are pulled along the spindle apparatus toward the center of the cell. They line up in the middle of the cell at metaphase plate. Anaphase The microtubules (spindle fibers) of the spindle apparatus begin to shorten. The sister chromatids separate (apart). The chromosomes move toward the poles of the cell. Telophase The chromosomes arrive at the poles and begin to relax. Two new nuclear membranes begin to form and the nucleoli reappear. The spindle apparatus disassembles. Cytokinesis Cytoplasm will divide forming two new genetically identical daughter cells. In animal cells, microfilaments constrict, or pinch, the cytoplasm. They create a “cleavage furrow” In plant cells, a new structure, called a cell plate, forms ( which will eventually become the new cell wall) Quick Review – Place Cells in Mitosis Order A B D C E Let’s Review! http://highered.mcgrawhill.com/sites/0072437316/student_view0 /chapter11/animations.html Do Now Label the parts of the cell. What phases of mitosis? 9.3 Cell Cycle Regulation Normal Cell Cycle: Different cyclin / CDK (cyclin dependent kinases) combinations signal other activities These including ○ DNA replication ○ Protein synthesis ○ Nuclear division Quality Control Checkpoints The cell cycle has built-in checkpoints These monitor the cycle and can stop it if something goes wrong. Spindle checkpoints also have been identified in mitosis. Ex. If no spindle fibers – will stop before cytokinesis Cell Cycle Checkpoints *If G1 checkpoint shows cell is not ready for DNA replication, it enters G0 phase and will not divide.* When Cell Division Goes Wrong Begins as a single cell that undergoes “transformation” (process converting a normal cell into a cancer cell) Immune system fails to destroy cell. Cell proliferates and forms a tumor. Transformation Transformation is caused by mutations. Mutations can result from a variety of different “carcinogens” (things that cause cancer) Carcinogens Tobacco “Dip” : contains 28 known carcinogens. Cigarettes Carcinogens UV Light Causes skin cancer (most common type of cancer) Tanning beds linked to “melanoma”deadliest type of skin cancer. Carcinogens Pesticides Overexposure has been known to cause leukemia and lymphoma. Cancer Cells vs. Normal Cells Cancer cells lack density-dependent inhibition, causing cells to pile up on top of each other They proceed past checkpoints They are “immortal”, meaning they can divide an infinite number of times, whereas nomral cells divide only about 20-50 times before stopping. Tumors Benign tumor Abnormally growing mass of cells Can disrupt certain organs, ex: brain, if they get too big Can be completely removed with surgery Malignant tumor Spreads into neighboring tissues Can metastasize, enter blood and lymph vessels, and spread to other organs and parts of the body Types of Cancer Carcinomas Originates in external or internal “coverings” such as skin or the lining of the intestine Sarcomas In tissues that support the body such as bone and muscle Leukemias and lymphomas In blood-forming tissues such as bone marrow, spleen, and lymph nodes. Cancer Genetics Multiple changes in DNA are needed to cause cancer Cancer increase with age Certain cancers are inherited in certain families (chances to have it) Do Now What is the difference between a benign tumor and a malignant tumor? What category of cancer is found on the lining of different organs? Apoptosis Programmed cell death Cells going through apoptosis actually shrink and shrivel in a controlled process. Ex. Leave in Fall Ex. Webbed Fingers/Toes DNA Damaged Cells Stem Cells Unspecialized cells that can develop into specialized cells when under the right conditions Stem Cells (cont) Embryonic Stem Cells Adult Stem Cells •After fertilization, the resulting mass of cells divides repeatedly until there are about 100–150 cells. •Found in various tissues in the body and might be used to maintain and repair the same kind of tissue •These cells have not become specialized. •Less controversial because the adult stem cells can be obtained with the consent of their donor http://www.stemcellresearchfacts.com/definition.html Stem Cell Controversy http://www.youtube.com/watch?v=27skh7prkN0 &feature=related As a review… Draw out all of the phases of mitosis with colored pencils. Use 4 chromosomes