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Discov5 lecppt ch11

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  • 11.1 Stem Cells: Dedicated to Division Stem cells are a source of new cells. Stem cell technology offers much hope and some success. Embryonic stem cells are found only in very early stages of development. The use of embryonic stem cells is controversial. Induced pluripotent stem cells are derived from differentiated cells.
  • 11.2 Cancer Cells: Good Cells Gone Bad Cancer develops when cells lose normal restraints on division and migration. Cell division is controlled by positive and negative growth regulators. Gene mutations are the root cause of all cancers. Most human cancers are not hereditary. Cancer develops as multiple mutations accumulate in a single cell. The challenge in cancer treatment is to destroy malignant cells selectively. Avoiding risk factors is the key to cancer prevention.
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    • 1. Discover BiologyFIFTH EDITIONCHAPTER 11Stem Cells, Cancer, and Human Health© 2012 W. W. Norton & Company, Inc.Anu Singh-Cundy • Michael L. Cain
    • 2. Henrietta Lacks’s Immortal Cells• Cervical cancer cells from Lacks were the firstto be grown in a laboratory setting and arestill being used today• HeLa cells are among the fastest-dividinghuman cells ever known• Lacks’s cells are immortal and have the abilityto divide indefinitely
    • 3. The Cell Is the Basic Unit of All Life• Genes contained in cellular DNA are theblueprint for cell growth and differentiation• Genetics, as well as external cues, promptcells to differentiate into a particular cell type• Differentiated cells exhibit differentcharacteristics based on gene expression
    • 4. Stem Cells: Dedicated to Division• Stems cells are a vital part of human growth,development, and maintenance• Undifferentiated stem cells can be found intissues throughout the body:– Bone marrow– Skin– Liver
    • 5. Stem cells are a source of new cells• Mitotic division of stem cells generates twoidentical daughter cells• Daughter cells can take one of two paths:– Maintain the stem cell population– Differentiate in order to perform a specializedfunction
    • 6. Stem cells are a source of new cells• Human embryonic stem cells are found only inembryos and can differentiate into any type ofspecialized cell• Adult stem cells can differentiate intospecialized cell types of the tissue or organ inwhich they are found
    • 7. Stem cell technology offers much hopeand some success• Studying stem cells and their development willhelp us to understand diseases andabnormalities such as cancer• Pharmaceutical companies can use stem cellsto increase drug development and lower costs• Regenerative medicine uses stem cells torepair damaged or diseased tissues
    • 8. Embryonic stem cells are found only invery early stages of development• A morula is a mass of undifferentiatedtotipotent stem cells, at 3–4 days afterfertilization,that can give rise to any cell typein the organism• A blastocyst contains pluripotent stemcells, at 5–7days after fertilization, that candifferentiate into the embryo and any cell typein the adult body
    • 9. Embryonic stem cells are found only in veryearly stages of development• Pluripotent stem cells cannot give rise to cellsthat make up the birth sac in mammals• Multipotent stem cells are adult stem cellsthat can differentiate into a limited number ofspecialized tissues• Unipotent stem cells are adult stem cells thatgive rise to only one specialized cell type
    • 10. The use of embryonic stem cells is controversial• Blastocysts are the only source of pluripotentstem cells• Scientists have used IVF embryos to produce aline of human embryonic stem cells• Advocates of embryonic stem cell researchbelieve it will produce promising therapeuticapplications• Opponents believe embryos have moral statusand it is unethical to use one embryo to benefitanother
    • 11. Induced pluripotent stem cells are derived fromdifferentiated cells• Induced pluripotent stem cells (IPSec) can bederived from differentiated adult cells• iPSCs are genetically altered to regain theflexibility of the embryonic pluripotent stemcells• IPSec technology is a promising new therapythat has yet to be tested on humans
    • 12. Cancer Cells: Good Cells Gone Bad• Cancer accounts for over a half-million deathseach year• There are more than 8 million Americansdiagnosed with cancer at any one time• The estimated cost of treating cancer in theUnited States is over $100 billion each year
    • 13. Cancer develops when cells lose normalrestraints on division and migration.• A single cell that divides unrestrained can leadto a cell mass called a tumor• A benign tumor is one that has been confinedto one site• Normal cells are anchorage dependent; cancercells continue to divide after detachment• Angiogenesis increases blood supply to tumorcells, enabling them to proliferate
    • 14. Cancer develops when cells lose normalrestraints on division and migration• Malignant cancer cells invade other tissuesand metastasize• Certain cancers are more prone to metastasis• Cancer cells that impair the function of vitalorgans often lead to death
    • 15. Cell division is controlled by positiveand negative growth regulators• Cell division is controlled by positive and negativegrowth regulators• Hormones can act as either positive or negativegrowth regulators depending on the tissue• Negative growth regulators can promptprogrammed cell death to eliminate damagedcells• A malfunction in either of the growth regulatorscan lead to cancer
    • 16. Gene mutations are the root cause ofall cancers• Gene mutations can lead to an abnormallyhigh or low production of certain proteins• Proto-oncogenes code for positive growthregulators and can trigger excessive cellproliferation as a result of mutations• Ontogenesis are cancerous cells that resultfrom mutations in proto-oncogenes
    • 17. Gene mutations are the root cause ofall cancers• Tumor suppressor genes are negative growthregulators that restrain cell division andmigration by:– Inhibiting the cell cycle– Stimulating repair of damaged DNA– Promoting cell adhesion– Controlling anchorage dependence– Preventing angiogenesis
    • 18. Most human cancers are nothereditary• Only a small percentage of cancers are theresult of inherited gene mutations• Inheriting a gene linked to cancer means anindividual has a higher risk of developingcancer• A majority of people develop cancer as aresult of a combination of environmentalagents and somatic mutations
    • 19. Cancer develops as multiple mutationsaccumulate in a single cell.• Mutations accumulate over time in cells• A sequential breakdown of proto-oncogenesand tumor suppressor genes results in tumorgrowth• Gene p53 plays a vital role in maintaining thecellular process• More than half of all cancers indicate a loss ofp53 activity in tumor cells
    • 20. The challenge in cancer treatment is todestroy malignant cells selectively• Cryosurgery and hormone therapy are used totreat abnormal or cancerous cells in a smallregion• Radiation and chemotherapy are standardcancer treatments that affect both cancerousand healthy cells• More selective cancer therapies are beingtested in clinical trails
    • 21. Avoiding risk factors is the key tocancer prevention• Carcinogens are physical, chemical, orbiological agents that may cause cancer– Bacteria or viruses– Increased exposure to hormones– Toxic chemicals• Two unavoidable risk factors include inheritedgenes and aging
    • 22. How HeLa Cells Changed Biomedicine• HeLa cells have allowed pharmaceuticalcompanies to research and develop drugsworth billions of dollars• HeLa cells have helped develop the field ofvirology and further the study of viruses suchas measles, mumps, and AIDS• Researchers used HeLa cells to show that theHPV infection can cause cancer
    • 23. Clicker QuestionsCHAPTER 11Stem Cells, Cancer, and Human Health
    • 24. Concept QuizAn example of a negative growth regulatorisA. An oncogeneB. A tumor suppressorC. A proto-oncogeneD. A kinase
    • 25. Concept QuizWhich of the following is not usually a causeof cancer in humans?A. Environmental pollutantsB. Genetic predispositionC. VirusesD. Cigarette smoke
    • 26. Concept QuizWhy is p53 important in the cell?A. It is a tumor suppressor that stops cells from dividing.B. It blocks cells with DNA damage from dividing.C. It causes cells with extreme DNA damage to die.D. All of the above