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

© 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

© 2013 Pearson Education, Inc. 1 What Is Cancer?

© 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

© 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

© 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

© 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).

© 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

© 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)

© 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)

© 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

© 2013 Pearson Education, Inc. 2 Passing Genes and Chromosomes to Daughter Cells

© 2013 Pearson Education, Inc. AnimationAnimation: The Structure of DNA Click “Go to Animation” / Click “Play” BioFlix: DNA ReplicationDNA Replication

© 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

© 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

© 2013 Pearson Education, Inc. AnimationAnimation: The Cell Cycle Click “Go to Animation” / Click “Play”

© 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

© 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

© 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

© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis

© 2013 Pearson Education, Inc. 3 The Cell Cycle and Mitosis - Mitosis

© 2013 Pearson Education, Inc. AnimationAnimation: Mitosis Click “Go to Animation” / Click “Play” BioFlix: MitosisMitosis

© 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

© 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

© 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

© 2013 Pearson Education, Inc. 4 Cell Cycle Control and Mutation

© 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

© 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

© 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

© 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.

© 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

© 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

© 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

© 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)

© 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.

© 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

© 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

© 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

© 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.

© 2013 Pearson Education, Inc. 6 Meiosis I

© 2013 Pearson Education, Inc. 6 Meiosis II

© 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

© 2013 Pearson Education, Inc. BioFlix: MeiosisMeiosis AnimationAnimation: Meiosis Click “Go to Animation” / Click “Play”

© 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)

© 2013 Pearson Education, Inc. 6 Comparison of Mitosis and Meiosis

© 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.

© 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.

© 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.

© 2013 Pearson Education, Inc. How many chromosomes does a human body cell contain?  12  23  34  46

© 2013 Pearson Education, Inc. How many chromosomes does a human body cell contain?  12  23  34  46

© 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.

© 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.

© 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

© 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

© 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.

© 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.

© 2013 Pearson Education, Inc. The genes that encode the proteins regulating the cell cycle are called ________.  oncogenes  proto-oncogenes  carcinogens  malignant

© 2013 Pearson Education, Inc. The genes that encode the proteins regulating the cell cycle are called ________.  oncogenes  proto-oncogenes  carcinogens  malignant

© 2013 Pearson Education, Inc. True or False: Chemotherapy causes hair loss because hair follicles divide rapidly, like cancer cells.  True  False

© 2013 Pearson Education, Inc. True or False: Chemotherapy causes hair loss because hair follicles divide rapidly, like cancer cells.  True  False

© 2013 Pearson Education, Inc. At what stage of meiosis does crossing over occur?  metaphase I  metaphase II  prophase I  prophase II

© 2013 Pearson Education, Inc. At what stage of meiosis does crossing over occur?  metaphase I  metaphase II  prophase I  prophase II

© 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

© 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

© 2013 Pearson Education, Inc. What does this figure show?  centromere  karyotype  cancerous cells  animal cells of different sizes

© 2013 Pearson Education, Inc. What does this figure show?  centromere  karyotype  cancerous cells  animal cells of different sizes