or The Secret Life of Cells: The Phases of Mitosis Divvying Up the Goods or The Secret Life of Cells: The Phases of Mitosis

Section 8.2 Summary – pages 201 - 210 Surface area-to-volume ratio Surface area = 96 mm2 Volume = 64 mm3 4 mm 4 mm 1 mm 1 mm 2 mm 2 mm 1 mm 2 mm Surface area = 6 mm2 Volume = 1 mm3 4 mm Surface area = 24 mm2 Volume = 8 mm3 If cell size doubled, the cell would require eight times more nutrients and would have eight times more waste to excrete. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Cell Reproduction *Cell division is the process by which new cells are produced from one cell. *Cell division results in two cells that are nearly identical to the original, parent cell. This is one of the processes for asexual (no sex) reproduction. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Results of Mitosis Click image to view movie. Section 8.2 Summary – pages 201 - 210

The Secret Life of Cells: The Phases of Mitosis Cell mitosis – jazz! DNA replication and more Mitosis DNA tube Cells alive – step wise mitosis How big are cells & viruses

Role play cell division Use 12 pipe cleaners – 30 cm, 15 cm and 7.5 cm and twist together as demonstrated. What do they represent? Prior to mitosis what do these structures do?

Role play cell division Use 2m yarn as cell membrane and 1m to represent nuclear membrane. Where should the chromosomes go? What stage is your cell in? Dissolve your nuclear membrane Compete the rest of the stages as outlined on p. 123.

Section 8.2 Summary – pages 201 - 210 The Cell Cycle The majority of a cell’s life is spent in the growth period known as interphase Following interphase, a cell enters its period of division called mitosis. Following mitosis, the cytoplasm divides, separating the two daughter cells or Cytokinesis Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Interphase: A Busy Time Interphase, the busiest phase of the cell cycle, is divided into three parts. Interphase DNA synthesis and replication Centrioles, mitochondria and other organelles replicate to provide enough cellular machinery to keep future daughter cells going. Rapid growth and metabolic activity Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Unlocking the Secret Life of Cells: The Phases of Mitosis *The four phases of mitosis are prophase metaphase anaphase telophase Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Prophase: The first phase of mitosis During prophase, the chromatin (DNA) coils to form visible chromosomes. Spindle fibers Disappearing nuclear envelope Chromosome coil into a tighter structure or condense. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Prophase: The first phase of mitosis Sister chromatids (coiled up copied chromosomes) are held together by a structure called a centromere, which later attaches to the spindle fibers for sorting into the new cells. Sister Chromotids Centromere Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 The structure of eukaryotic chromosomes during mitosis (larger to smaller) Centromere Sister chromatids Supercoil within chromosome Chromosome Continued coiling within supercoil Histone H1 Nucleosome DNA Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Metaphase: The second stage of mitosis During metaphase, the chromosomes move to the equator of the spindle. Centromere Sister chromatids Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Anaphase: The third phase of mitosis During anaphase, the centromeres split and the sister chromatids are pulled apart to opposite poles of the cell. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Telophase: The fourth phase of mitosis During telophase, two distinct daughter cells are formed. The cells separate as the cell cycle proceeds into the next interphase. Nuclear envelope reappears Two daughter cells are formed Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Cytokinesis Following telophase, the cell’s cytoplasm divides in a process called cytokinesis. Toward the end of telophase in animal cells, the plasma membrane pinches in along the equator. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Cytokinesis Plant cells have a rigid cell wall, so the plasma membrane does not pinch in. *In plants, a structure known as the cell plate is laid down across the cell’s equator. *In plants, A cell membrane forms around each cell, and new cell walls form on each side of the cell plate until separation is complete. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 **Results of Mitosis When mitosis and cytokinesis is complete, unicellular organisms remain as single cells. In multicellular organisms, cell growth and replication result in groups of cells that work together as tissue to perform a specific function. Section 8.2 Summary – pages 201 - 210

Section 8.2 Summary – pages 201 - 210 Results of Mitosis Tissues organize in various combinations to form organs that perform more complex roles within the organism. Multiple organs that work together form an organ system. Section 8.2 Summary – pages 201 - 210

What is cancer? *Cancerous cells form masses of tissue called tumors that deprive normal cells of nutrients. *In later stages, cancer cells enter the circulatory system and spread throughout the body, a process called metastasis, forming new tumors that disrupt the function of organs, organ systems, and ultimately, the organism.

What causes cancer? * Many cancer cells have too many chromosomes. This can occur when a mistake in divvying up chromosomes between cells can occur. *Uncontrolled dividing of cells can result from the failure of the enzymes (proteins) that regulate cell reproduction. *Enzyme production is directed by genes located on the chromosomes. A mistake in your DNA can result in cancer. Some families have a greater tendency to get certain cancers (an inherited trait).

Section 8.3 Summary – pages 211 - 213 The causes of cancer *Cancer can be caused by chemicals in food, drugs or environment. * Cancer can be caused by radiation of wave lengths smaller than ultraviolet light. *Cancer may also be caused by viral infections that damage the genes. HPV causes cancer in women and is a sexually transmitted disease. A vaccine is currently available to help with the spread of this disease. Section 8.3 Summary – pages 211 - 213

Section 8.3 Summary – pages 211 - 213 Cancer prevention *Physicians and dietary experts agree that diets low in fat and high in fiber content can reduce the risk of many kinds of cancer. *Vitamins and minerals may also help prevent cancer. Eat your fruits and veggies every day or eat a rainbow of colors. Sexual contact limited to one partner after marriage. Section 8.3 Summary – pages 211 - 213

Videos – excellent explanation of cells and cancer cause Cancer video on new cures CPB videos – telomeres