Why does a cell divide? Efficiency Smaller the cell = quicker it can work Transport of Substances Cellular communication Ratio of surface area to volume

Other reasons for cellular division Growth Replace damaged cells

The Cell Cycle Cell reaches max size it stops growing or divides Cells reproduce by growing and dividing = cell cycle 3 main stages of cell cycle Interphase – cell grows, replicates DNA Mitosis – nucleus and nuclear material divide Cytokinesis – cytoplasm divides

3 Stages of Interphase Gap 1 (G1) normal functions Synthesis (S) Cell copies DNA Gap 2 (G2) Cell prepares for mitosis

Mitosis Cell’s DNA separates Creates 2 identical daughter cells Same Number of Chromosomes 4 Stages – Prophase, Metaphase, Anaphase, Telophase

1. Prophase Chromatin condenses into chromosomes X – shaped Consist of two chromatids – identical copies of DNA Chromatids are connected at a centromere

1. Prophase Nuclear membrane disappears Spindle apparatus appears Spindle fibers, centrioles, and aster fibers

2. Metaphase Chromatids Line up at center of cell

3. Anaphase Chromatids pull apart

4. Telophase Chromosomes arrive at the poles Chromosomes unwind Two nuclear membranes begin to form Spindle apparatus disappears

Cytokinesis Divides cytoplasm Animal Cells Plant Cells Microfilaments constrict/pinch the cytoplasm Plant Cells Cell plate forms between two daughter nuclei Cell walls then form on either side of cell plate

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html http://www.sumanasinc.com/webcontent/animations/content/mitosis.html

https://www.youtube.com/watch?v=L0k-enzoeOM

Cancer Uncontrolled cell division Tumors begin with a single cell that reproduces by mitosis Cells in tumors divide continuously Metastasis: Process in which cells are invasive and move to other sites in the body

The Cell Cycle and Cancer Benign = not cancerous Do not invade neighboring tissue or spread Malignant = cancerous Readily invade neighboring tissues May also detach and lodge in distant places – metastasis

Cell grows, doubles in size Chromosome duplication G2/M checkpoint 4 Cell division Mitosis 3 DNA repair G2 1 Cell grows, doubles in size G1 S 2 Chromosome duplication Checkpoints in the cell cycle regulate cell division G1/S checkpoint Stepped Art p. 181

How does it happen? Oncogenes are activated Normal function: cell growth, gene transcription Tumor suppressor genes are inactivated Normal function: DNA repair, cell cycle control, cell death

Tumor suppressors “Guardian(s) of the genome” Often involved in maintaining genomic integrity (DNA repair, chromosome segregation)‏ Mutations in tumor suppressor genes lead to the “mutator phenotype”—mutation rates increase Often the 1st mutation in a developing cancer P53 and Rb

Causes of Cancer Mutation: change in genetic makeup Any agent that causes cancer is called a carcinogen and is described as carcinogenic Infection Viruses (EBV, hepatitis B, papilloma) Bacteria (Helicobacter)

Lifestyle Risks Smoking Diet high fat and low in fruits and vegetables Lack of exercise Unprotected exposure to the sun, (UV) rays Obesity Stress Jobs – exposed to chemicals, etc Radiation

Environmental Risks Second hand smoke PCB’s Air pollution Industrial pollution Chemical exposures tar from cigarettes some foods

Inherited Risks Less than 15% of cancers are inherited Some families are more susceptible to getting certain cancers You can’t inherit cancer its just that you maybe more susceptible to getting it

Treatment Chemotherapy treatment uses medicine to weaken and destroy cancer cells in the body affects the whole body Radiation therapy (also called radiotherapy) high-energy rays are used to damage cancer cells and stop them from growing and dividing local treatment; it affects cancer cells only in the treated area

Cancer Prevention Healthy lifestyle Exercise and proper breathing Balanced diet Complete rest and sleep Water Eating Fruit

Explain what happens in each step of mitosis. Agenda for Review mitosis (video?) Mitosis Cell Lab

If a cell has 150 chromosomes how many daughter cells are created at the end of mitosis? How many chromosomes are in each cell? Agenda for Finish lab Finish worksheets Start cancer notes

What is cancer? Agenda for Cancer Notes Go over worksheets and lab Cancer worksheet