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Skin Cells: 20 days Red Blood Cells: 120 days Stomach lining cells: 2 days Brain cells: years Platelets: 10 days Intestinal lining cells: 3 days ______________________

DNA plus proteins is called chromatin. One half of a duplicated chromosome is a chromatid. Sister chromatids – chromosome after it has made an exact copy. Held together at the centromere. Telomeres protect DNA and do not include genes. Condensed, duplicated chromosome chromatid telomere centromere telomere

The four stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis. 1) Gap 1 (G 1 ): cell growth and normal functions Mitosis occurs only if the cell is large enough and the DNA undamaged. 2) DNA synthesis (S): copies DNA 3) Gap 2 (G 2 ): additional growth 4) Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)

Parent cell centrioles spindle fibers centrosome nucleus with DNA Interphase prepares the cell to divide. During interphase, the DNA is duplicated. Mitosis and cytokinesis produce two genetically identical daughter cells.

Prophase Metaphase Anaphase Telophase _______________________________________

Sister Chromatids Nuclear Membrane CentriolesFibers Shorten and Thicken Begins to break down Move apart from one another Form between centrioles

Sister Chromatids Nuclear Membrane CentriolesFibers Become attached to the fibers. Are pulled to middle of cell Remains dissolved Move to opposite ends of cells Are stretched between the two ends of cell

Sister Chromatids Nuclear Membrane CentriolesFibers Pulled apart by fibers. Each chromatid is separate from its “sister” Remains dissolved Still at cell’s poles; Pull each chromatid toward opposite ends of cell

Sister Chromatids Nuclear Membrane Cell Membrane Fibers Each end of cell has a complete set of chromosomes. Begins to reform Begins to pinch, forming two new cells Begin to disappear

Cytokinesis differs in animal and plant cells. –In animal cells, the membrane pinches closed. –In plant cells, a cell plate forms.

The process is VERY SIMILAR in each type of cell. There are only 2 differences: 1.Plant cells do not have centrioles 2.A cell wall is laid down at the end of the cell division.

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_____________________________ Life Cycle Animation

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Cancer cells form disorganized clumps called tumors. Benign tumors remain clustered and can be removed. Malignant tumors metastasize, or break away, and can form more tumors. cancer cell bloodstream normal cell Cell division is uncontrolled in cancer.

Cancer cells do not carry out necessary functions and crowd out normal cells. Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

Carcinogens are substances known to promote cancer. Standard cancer treatments typically kill both cancerous and healthy cells.

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ORGANISM“GUESSTIMATE”ACTUAL CHROMOSOME # CAT DOG CHIMPANZEE EARTHWORM GOLDFISH CARROT LETTUCE ONION CHICKEN GUINEA PIG HUMAN MOSQUITO PEA PENICILLIN CORN FROG

Stem cells are unique body cells. Stem cells have the ability to –divide and renew themselves –remain undifferentiated in form –develop into a variety of specialized cell types

Stem cells are classified into three types. –totipotent, or growing into any other cell type –pluripotent, or growing into any cell type but a totipotent cell –multipotent, or growing into cells of a closely related cell family

Stem cells come from adults and embryos. –Adult stem cells can be hard to isolate and grow. –The use of adult stem cells may prevent transplant rejection. –The use of embryonic stem cells raises ethical issues –Embryonic stem cells are pluripotent and can be grown indefinitely in culture. First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

The use of stem cells offers many currently realized and potential benefits. –Stem cells are used to treat leukemia and lymphoma. –Stem cells may cure disease or replace damaged organs. –Stem cells may revolutionize the drug development process.