The Process of Cell Growth & Division

1. How is the life cycle of a human and a single cell similar? 1. How is the life cycle of a human and a single cell similar? 2. How is the life cycle of a human and a single cell different? 2. How is the life cycle of a human and a single cell different? 3. Compare the life of cell to the clock – in 12 hours how long does the cell spend actually dividing? 3. Compare the life of cell to the clock – in 12 hours how long does the cell spend actually dividing? 4. Why do you think cells make a copy of their DNA before they divide in half?

Is it easier to use string when it is spread out or spooled up? 5. Is it easier to use string when it is spread out or spooled up? 6. Is it easier to transport string when it is spread out or spooled up?

7. What do we call DNA that is spread out? 8. What do we call DNA that is coiled up? 9. Compare the string to DNA. Do you think it is easier for the cell to read (and use) the DNA when it is chromatin or chromosomes? 10. Compare the string to DNA. Do you think it is easier for the cell to pass the DNA onto future generations when it is chromatin or chromosomes? 10. Compare the string to DNA. Do you think it is easier for the cell to pass the DNA onto future generations when it is chromatin or chromosomes?

1. What are the two parts of the cell cycle? 2. Summarize what occurs during interphase? 3. What is the difference between mitosis and cytokinesis? Growth and RegulationGrowth and Regulation

4. What is G 0 ? What types of cells in your body are in G 0 ?

Growth and RegulationGrowth and Regulation 5. Why do cells divide? 6. How many times can a normal cell divide? 7. What are the three ways normal growth is controlled? Explain each method.  anchorage dependence  density-dependent inhibition.  Proto-oncogenes

Growth and RegulationGrowth and Regulation 8. What is a stem cell? 9. What is apoptosis? 10. Why is apoptosis so important to cells?

Growth and RegulationGrowth and Regulation 11. What is cancer? 12. What is a tumor?  Cancer is a disease caused by normal cells changing so that they grow in an uncontrolled way. The uncontrolled growth causes a lump called a tumor to form.

Growth and RegulationGrowth and Regulation 13. How many different types of cancer are there? 14. Why are there so many types of cancer? 15. List 5 different types of cancer that you have heard of

2009 Estimated US Cancer Cases*2009 Estimated US Cancer Cases* *Excludes basal and squamous cell skin cancers and in situ carcinomas except urinary bladder. Source: American Cancer Society, Men 766,130 Women 713,220 27%Breast 14%Lung & bronchus 10%Colon & rectum 6%Uterine corpus 4%Non-Hodgkin lymphoma 4%Melanoma of skin 4% Thyroid 3%Kidney & renal pelvis 3%Ovary 3%Pancreas 22%All Other Sites Prostate25% Lung & bronchus15% Colon & rectum10% Urinary bladder7% Melanoma of skin5% Non-Hodgkin5% lymphoma Kidney & renal pelvis5% Leukemia 3% Oral cavity3% Pancreas3% All Other Sites19%

US Mortality, 2006US Mortality, 2006  1.Heart Diseases631,   2.Cancer559,  3.Cerebrovascular diseases137,   4.Chronic lower respiratory diseases124,   5.Accidents (unintentional injuries)121,   6.Diabetes mellitus 72,   7.Alzheimer disease 72,   8.Influenza & pneumonia 56,  9. Nephritis* 45,  10.Septicemia 34, *Includes nephrotic syndrome and nephrosis. Source: US Mortality Data 2006, National Center for Health Statistics, Centers for Disease Control and Prevention, RankCause of Death No. of deaths % of all deaths

2009 Estimated US Cancer Deaths*2009 Estimated US Cancer Deaths* ONS=Other nervous system. Source: American Cancer Society, Men 292,540 Women 269,800 26%Lung & bronchus 15%Breast 9%Colon & rectum 6%Pancreas 5%Ovary 4%Non-Hodgkin lymphoma 3%Leukemia 3%Uterine corpus 2% Liver & intrahepatic bile duct 2%Brain/ONS 25% All other sites Lung & bronchus30% Prostate9% Colon & rectum 9% Pancreas6% Leukemia4% Liver & intrahepatic4% bile duct Esophagus4% Urinary bladder3% Non-Hodgkin 3% lymphoma Kidney & renal pelvis3% All other sites 25%

Growth and RegulationGrowth and Regulation 16. How many times can cancer cells divide? 17. Why do scientists describe cancer cells as immortal? (two reasons) 18. Why can cancer cells spread while normal cells can not?

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Like Begets Like  Cell theory states that ‘cells come from pre-existing cells’ (Rudolf Virchow 1858)  Some organisms create identical offspring – through asexual reproduction  Some organisms create similar, but not identical offspring – through sexual reproduction  Reproduction on the cellular level is called cell division.

Prokaryotic vs Eukaryotic Cells  Remember that prokaryotic cells are:  Smaller than Eukaryotic Cells  Simpler than Eukaryotic Cells  It turns out that their DNA is also:  Shorter than Eukaryotic Cells  3,000 vs 300,000 genes long  Organized into only 1 strand, while Eukaryotic cells its organized into many  1 chromosome in a bacterium vs 46 in a human

A closer look at Eukaryotic DNA throughout the life of the cell…  Day-to-day the DNA is coiled around histone proteins into threads called chromatin.  Before dividing the DNA replicates (makes an identical copy of itself). The copy attaches to the original forming somewhat of an X like structure. These are called chromatids.  When dividing the DNA coils even further into short rods called chromosomes. These are so dense they can be easily seen through a microscope.

G1 S G2 M phase

S phase G1 phase G2 phase

Growth (Interphase)  G1: Gap 1  Cell grows bigger and makes proteins needed for life.  S Phase: DNA Synthesis  During the S phase, the cell replicates its DNA.  G2: Gap 2  Cell grows even bigger and makes proteins needed for two cells!

 Cells can live their entire life growing. An example of this is nerve cells in humans. They never progress past this part of the cell cycle.  Most cells, though, will divide (reproduce) at some point. Why would cells divide?  Survival (they have become too big)  DNA overload  Cell Transport overload  Benefit of the larger organism  Grow  Heal  If a cell is going to divide it will continue through this sequence… Not in notes – jot down what you think is important

Division of a Prokaryotic Cell  Called Binary Fission  Chromosomes segregate (move to opposite sides of the cell)  Cell elongates and divides

Division of an Eukaryotic Cell  There are 2 stages to Division:  Division of the DNA (MITOSIS) 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase  Division of the cytoplasm (CYTOKINESIS)

Prophase  Think Prepare -  The DNA coils into chromosomes.  Now visible by microscope  Centrioles and spindle fibers take their places This is a picture of a cell in prophase.

Prometaphase  Think Prepare for Metaphase  Spindle fibers attach to kinetochore  Nuclear envelope disappears

Metaphase  Think Middle -  Chromosomes line up at the center of the cell.  Chromosomes line up at metaphase plate equidistant between two poles. This is a picture of a cell in metaphase.

Anaphase  Think - apart  Each centromere divides.  Motor proteins of kinetochores walk daughter chromosomes towards opposite poles  Sister chromatids separate and move apart. This is a picture of a cell in anaphase.

Telophase/Cytokinesis  Think - two  Two nuclear membrane are formed  Chromosomes uncoil  Mitotic spindles disappear  Nucleoli reappear  Cytokinesis  Division of cytoplasm This is a picture of a cell in telophase. This is a picture of a cell in cytokinesis.

Videos of DivisionVideos of Division  html html  hill.com/sites/ /student _view0/chapter2/animation__mito sis_and_cytokinesis.html hill.com/sites/ /student _view0/chapter2/animation__mito sis_and_cytokinesis.html  on.com/anim_mitosis.html on.com/anim_mitosis.html

Cytokinesis in Animal Cells Cell’s membrane pinches inward until the two sides touch resulting in two separate daughter cells.

Cytokinesis in Plant Cells Cell’s membrane CAN NOT pinch inward because of the rigid cell wall. Instead, a cell plate forms between the two nuclei and slowly grows into a new wall separating the two daughter cells

S phase G1 phase G2 phase

Cell Cycle in Onion Cells interphaseprophasemetaphase anaphaseTelophase / cytokinesis

Cancer  Cancer starts in one cell with one mutation. This mutation causes the cell to ‘cycle’ faster than it should.  Over time – additional mutations occur in the cell. These mutations cause the cell to ‘cycle’ even faster – essentially the cell loses control!

Cancer  Mutations can be –  Inherited from your parents  Random  Caused by chemicals / environmental factors (carcinogens / mutagens)  Cigarette smoke  Chewing tobacco  Asbestos  UV light  X-rays

Cancer  Mutations that cause cancer are specific – they must affect the speed of the cell cycle and its survival!  Proto-oncogenes mutate to oncogenes (fast forward)  Tumor suppressor genes mutate to stop working (breaks fail)  Angiogenesis genes are mutated to become active (unlimited food)  P53 gene is mutated to stop working (immortal)  Various genes mutate to allow metastasis (cells spread)  Most cancers are caused by 5-10 mutations. Cancer is a disease of multiple mutations in one cell.

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Magic BulletsMagic Bullets  Mitch  Leukemia – white blood cells  Symptoms – back pain  Treatment – Glevic (magic bullet that blocks an oncogene)  Jeff  Kidney Cancer that spread to abdonmen  Treatments – Anti-Veg-F (magic bullet that blocks angiogenesis)

The End