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Copyright © 2009 Pearson Education, Inc. © 2013 Pearson Education, Inc. PowerPoint Lecture prepared by Jill Feinstein Richland Community College Fourth Edition BIOLOGY Science for Life | with Physiology Colleen Belk Virginia Borden Maier Chapter 4 Cancer DNA Synthesis, Mitosis, and Meiosis
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© 2013 Pearson Education, Inc. 1 What Is Cancer? Tumor: Unregulated cell division that form a mass of cells with no function Benign tumor: doesn’t affect surrounding tissues Malignant tumor: invades surrounding tissues; cancerous Metastasis: cells break away from a malignant tumor and start a new cancer at another location
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© 2013 Pearson Education, Inc. 1 What Is Cancer?
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© 2013 Pearson Education, Inc. 1 What Is Cancer? Metastatic cells can travel throughout the body via the circulatory system or the lymphatic system. Once in either system the cancer cells can travel anywhere in the body Cancer cells differ from normal cells: Divide when they shouldn’t Invade surrounding tissues Move to other locations in the body
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© 2013 Pearson Education, Inc. 1 What Is Cancer? Risk factors: increase a person’s risk of developing a disease (Table 6.1) Tobacco use: tobacco contains many carcinogens Alcohol consumption High-fat, low-fiber diet Lack of exercise Obesity Increasing age which weakens the immune system Cells that divide frequently such as ovarian cells
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells Asexual reproduction: Only one parent Offspring are genetically identical to parent Sexual reproduction Gametes are combined from two parents Offspring are genetically different from one another and from the parents
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells Before dividing, cells must copy their DNA Gene: section of DNA that has the instructions for making all proteins One molecule of DNA is wrapped around proteins to form a chromosome containing hundreds of genes. Different species have different numbers of chromosomes (we have 46).
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells Chromosomes are uncondensed before cell division Duplicated chromosomes, held together at the centromere, are called sister chromatids They are duplicated through DNA replication
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells DNA molecule is a double stranded structure similar to a twisted ladder. The sides of the ladder are composed of a sugar- phosphate backbone. Nucleotides are connected to each other by hydrogen bonding to form the “rungs” of the ladder. Adenine (A) pairs with thymine (T) Cytosine (C) pairs with Guanine (G)
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells DNA molecule is split up the middle of the helix Nucleotides are added to each side via hydrogen bonding Result is two identical daughter molecules, each with one parental strand and one new strand (semiconservative replication)
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells DNA polymerase: the enzyme that replicates DNA It moves along the length of the unwound DNA and helps form the new strands
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© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells
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© 2013 Pearson Education, Inc. AnimationAnimation: The Structure of DNA Click “Go to Animation” / Click “Play” BioFlix: DNA ReplicationDNA Replication
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis Cell cycle has three steps: Interphase: the DNA replicates Mitosis: the copied chromosomes are moved into daughter nuclei Mitosis occurs in somatic or body cells. Cytokinesis: the cell is split into 2 daughter cells
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Interphase Interphase has three phases: G 1 : cell grows, organelles duplicate S: DNA replicates G 2 : cell makes proteins needed to complete mitosis Most of the cell cycle is spent in interphase
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© 2013 Pearson Education, Inc. AnimationAnimation: The Cell Cycle Click “Go to Animation” / Click “Play”
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis Mitosis produces genetically-identical daughter nuclei Mitosis is followed by cytokinesis which splits the two nuclei into two daughter cells Four stages: Prophase Metaphase Anaphase Telophase
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis Prophase: Chromosomes condense Nuclear envelope disappears Microtubules pull the chromosomes around during cell division Animal cells: microtubules attached to centrioles at the poles of the cell
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis Metaphase: Chromosomes are aligned across the middle of the cell by microtubules Anaphase : centromeres split, sister chromatids are pulled apart toward opposite poles Telophase: Nuclear envelopes reform around chromosomes Chromosomes revert to uncondensed form
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis
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© 2013 Pearson Education, Inc. AnimationAnimation: Mitosis Click “Go to Animation” / Click “Play” BioFlix: MitosisMitosis
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Cytokinesis Cytokinesis is the stage in which two daughter cells are formed from the original one After cytokinesis, cells reenter interphase. Animals: Proteins pinch the original cell into two new cells
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© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Cytokinesis Cytokinesis in Plants: Starts with vesicles forming the cell plate. This results in a new cell wall being formed between the cells forming daughter cells. The cell wall is made from cellulose
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation Cell division is a tightly controlled process Normal cells halt at checkpoints Proteins survey the condition of the cell Cell must pass the survey to proceed with cell division 3 checkpoints: G 1,G 2, and metaphase
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation Growth factors stimulate cells to divide Growth factors bind to receptors to trigger a response from a cell Mutation: a change in the sequence of DNA Changes to DNA can change the structure and function of the protein coded by the DNA Mutations may be inherited or caused by carcinogens
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation Proto-oncogenes: genes that code for the cell cycle control proteins When proto-oncogenes mutate, they become oncogenes Their proteins no longer properly regulate cell division They usually overstimulate cell division
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation Tumor suppressor genes: genes for proteins that stop cell division if conditions are not favorable When mutated, can allow cells to override checkpoints
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation Depending on the number of mutations and whether the tumor suppressor protein is functional will determine whether it is a benign or malignant tumor that is formed.
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© 2013 Pearson Education, Inc. 4 Cancer Development Requires Many Mutations Progression from benign tumor to cancer requires many mutations. Angiogenesis: tumor gets its own blood supply Loss of contact inhibition: cells will now pile up on each other Loss of anchorage dependence: enables a cancer cell to move to another location Immortalized: cells no longer have a fixed number of cell divisions due to an enzyme called telomerase
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© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation – Multiple Hit Model Multiple hit model: process of cancer development requires multiple mutations Some mutations may be inherited (familial risk) Most are probably acquired during a person’s lifetime
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© 2013 Pearson Education, Inc. 5 Cancer Detection and Treatment Early detection increases odds of survival There are different detection methods for different cancers Some cancers produce increased amount of a characteristic protein Biopsy: surgical removal of cells or fluid for analysis Needle biopsy: removal is made using a needle Laparascope: surgical instrument with a light, camera, and small scalpel
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© 2013 Pearson Education, Inc. 5 Cancer Detection and Treatment - Treatment Methods Chemotherapy: drugs that selectively kill dividing cells Combination of different drugs used (“cocktail”) Interrupt cell division in different ways Helps prevent resistance to the drugs from arising Normal dividing cells are also killed (hair follicles, bone marrow, stomach lining)
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© 2013 Pearson Education, Inc. 5 Cancer Detection and Treatment - Treatment Methods Radiation therapy: use of high-energy particles to destroy cancer cells Damages their DNA so they can’t continue to divide or grow Usually used on cancers close to the surface Typically performed after surgical removal of tumor If a person remains cancer free after treatment for 5 years they are in remission and after 10 years they are cured.
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© 2013 Pearson Education, Inc. 6 Meiosis Specialized form of cell division in gonads to produce gametes Reduces number of chromosomes in each cell by one-half Chromosomes come in homologous pairs Gamete gets one of each pair
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© 2013 Pearson Education, Inc. 6 Meiosis Chromosomes can be visualized using a karyotype. Human somatic cells have 22 pairs of autosomes and one pair of sex chromosomes
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© 2013 Pearson Education, Inc. 6 Meiosis Gametes are haploid or have 1 set of 23 chromosomes When the egg and sperm nuclei fuse it forms a zygote which is diploid Somatic or body cells are also diploid
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© 2013 Pearson Education, Inc. 6 Meiosis Starts with interphase – DNA is duplicated Meiosis takes place in two stages: Meiosis I Separating out the homologous pairs into 2 separate cells Meiosis II Separating out the sister chromatids in each cell to produce 4 haploid cells.
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© 2013 Pearson Education, Inc. 6 Meiosis I
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© 2013 Pearson Education, Inc. 6 Meiosis II
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© 2013 Pearson Education, Inc. 6 Meiosis Crossing over: exchange of equivalent portions of chromosomes between members of a homologous pair Results in new types of gametes being formed Linked genes typically cross over together Random alignment: the way in which different pairs of chromosomes align and get separated during meiosis I is random Results in different types of games being formed
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© 2013 Pearson Education, Inc. BioFlix: MeiosisMeiosis AnimationAnimation: Meiosis Click “Go to Animation” / Click “Play”
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© 2013 Pearson Education, Inc. 6 Meiosis - Mistakes in Meiosis Nondisjunction: failure of homologues to separate normally during meiosis Results in a gamete having one too many chromosomes (trisomy) or one too few chromosomes (monosomy) Most embryos that result from such gametes will die before birth Several chromosome abnormalities are known in humans (Table 6.2)
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© 2013 Pearson Education, Inc. 6 Comparison of Mitosis and Meiosis
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© 2013 Pearson Education, Inc. 6 Meiosis For cancer mutations to be passed on to offspring, they must take place in cells that give rise to gametes. Mutations caused by environmental exposures are not passed on unless the mutation occurs in the gametes. Mutations in somatic cells (e.g., skin cancer from UV ray exposure) are not heritable.
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© 2013 Pearson Education, Inc. Which of following statements incorrectly identifies how cancer cells differ from normal cells? Cancer cells divide when they should not. Cancer cells invade surrounding tissues. Cancer cells form benign tumors. Cancer cells can move to other locations in the body.
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© 2013 Pearson Education, Inc. Which of following statements incorrectly identifies how cancer cells differ from normal cells? Cancer cells divide when they should not. Cancer cells invade surrounding tissues. Cancer cells form benign tumors. Cancer cells can move to other locations in the body.
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© 2013 Pearson Education, Inc. How many chromosomes does a human body cell contain? 12 23 34 46
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© 2013 Pearson Education, Inc. How many chromosomes does a human body cell contain? 12 23 34 46
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© 2013 Pearson Education, Inc. Which statement correctly describes the role of DNA polymerase in DNA replication? DNA polymerase splits the double-stranded DNA in half. DNA polymerase helps bind incoming nucleotides to each other. DNA polymerase lines up chromosomes on the metaphase plate. DNA polymerase helps prevent the degradation of chromosomes.
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© 2013 Pearson Education, Inc. Which statement correctly describes the role of DNA polymerase in DNA replication? DNA polymerase splits the double-stranded DNA in half. DNA polymerase helps bind incoming nucleotides to each other. DNA polymerase lines up chromosomes on the metaphase plate. DNA polymerase helps prevent the degradation of chromosomes.
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© 2013 Pearson Education, Inc. During which phase of mitosis does the centromere split, allowing motor proteins to pull each sister chromatid to opposite poles of the cell? prophase metaphase telophase anaphase
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© 2013 Pearson Education, Inc. During which phase of mitosis does the centromere split, allowing motor proteins to pull each sister chromatid to opposite poles of the cell? prophase metaphase telophase anaphase
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© 2013 Pearson Education, Inc. A gene encoding a protein that regulates the G1 checkpoint is mutated What is a likely outcome? Tumors will develop. The cell will die. The cell will live but never divide. The cell will become larger and large.
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© 2013 Pearson Education, Inc. A gene encoding a protein that regulates the G1 checkpoint is mutated What is a likely outcome? Tumors will develop. The cell will die. The cell will live but never divide. The cell will become larger and large.
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© 2013 Pearson Education, Inc. The genes that encode the proteins regulating the cell cycle are called ________. oncogenes proto-oncogenes carcinogens malignant
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© 2013 Pearson Education, Inc. The genes that encode the proteins regulating the cell cycle are called ________. oncogenes proto-oncogenes carcinogens malignant
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© 2013 Pearson Education, Inc. True or False: Chemotherapy causes hair loss because hair follicles divide rapidly, like cancer cells. True False
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© 2013 Pearson Education, Inc. True or False: Chemotherapy causes hair loss because hair follicles divide rapidly, like cancer cells. True False
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© 2013 Pearson Education, Inc. At what stage of meiosis does crossing over occur? metaphase I metaphase II prophase I prophase II
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© 2013 Pearson Education, Inc. At what stage of meiosis does crossing over occur? metaphase I metaphase II prophase I prophase II
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© 2013 Pearson Education, Inc. A checkpoint is missing from this picture. Where is this checkpoint? at the beginning of G2 at the end of M phase during S phase at the end of G2
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© 2013 Pearson Education, Inc. A checkpoint is missing from this picture. Where is this checkpoint? at the beginning of G2 at the end of M phase during S phase at the end of G2
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© 2013 Pearson Education, Inc. What does this figure show? centromere karyotype cancerous cells animal cells of different sizes
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© 2013 Pearson Education, Inc. What does this figure show? centromere karyotype cancerous cells animal cells of different sizes
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