Name: Block: PACKET #9 Reading: Unit 4: Cell Development and Replication, Part I: The Cell Cycle Objectives: By the conclusion of this unit you will be able to: Date: Introduction to the cell cycle 1. Compare the process of cell division in prokaryotes and eukaryotes. 2. Explain the importance of the cell cycle. 3. Describe the main events of the cell cycle, including what happens during each stage of interphase G0, G1, S, and G2. DNA replication 4. Describe the structure of nucleotides and why they are paired the way they are (purines and pyrimadines). 5. Describe the structure of DNA (also refer to chapter 1) and explain how it is assembled into the chromosome. 6. Define and relate the following terms: chromatin, chromosomes, DNA, sister chromatids, centromere, replicated chromosomes, and homologous chromosomes. 7. Explain the process of DNA synthesis (replication). Cell division and control of the cell cycle 8. List the steps of mitosis and both describe and draw what occurs in each step. 9. Describe the major differences between cancer cells and normal cells and how the cell cycle may be altered in cancer. Key terms Binary Fission Cell cycle Mitosis Interphase G0 Phase G1 Phase S Phase G2 Phase M Phase Restriction point Nuclear division Cytokinesis Nucleotide Adenine Thymine Cytosine Guanine Uracil DNA synthesis (replication) DNA polymerase Replication origins Semi-conservative Chromosome Replicated Chromosome Sister chromatids Centromere Mutation Spindle Prophase Metaphase Anaphase Telophase Cell cycle arrest 1
Objective 1: Compare the process of cell division in prokaryotes and eukaryotes. Objective 2: Explain the importance of the cell cycle. Objective 3: Describe the main events of the cell cycle, including what happens during each stage of interphase G0, G1, S, and G2, be sure to include the restriction point. Phase Sub-phase Description of Events Interphase G0 G1 S G 2 M Phase Watch each of the following short animations/video clips, as found at http://iknow.net/cell_div_education.html Cell cycle movie Plant mitosis movie Embryonic division zebrafish Animal mitosis movie lung cell 2
Objective 4: Describe the structure of nucleotides of DNA. Objective 5: Describe the structure of DNA and explain how it is assembled into the chromosome. 3
Objective 6: Define and relate the following terms: chromatin, chromosomes, DNA, sister chromatids, centromere, replicated chromosomes, and homologous chromosomes. Compare and contrast two sister chromatids of one chromosome and two homologous chromosomes. Relate the structure of a replicated chromosome to an unreplicated chromosome. Drawing Definition Single, unreplicated chromosome Replicated chromosome Homologous chromosome pair 4
Objective 7: Explain the process of DNA replication (use a diagram to help) (8.4). STEP Binding of enzymes to existing DNA DESCRIPTION Unwinding of the double helix Synthesis of a new matching strand for each existing strand TERM Helicase DEFINITION AND/OR ROLE IN THE PROCESS Replication fork (origin) DNA polymerase Semiconservative Lagging and Leading Strands 5
DNA Structure and Replica2on Prac2ce ques2ons 1.) Place the following in order, from small to big: Nucleus of a cell Nucleic acid molecule Neutron Nitrogen atom Nitrogenous base Nucleo;de 2.) is the type of monomer that is repeated to make a nucleic acid, just as glucose monomers are repeated to make a polysaccharide (or amino acid monomers to make a protein). 3.) This monomer is made of a sugar group, a phosphate group, and a that have been bonded together. 4.) In a single strand of DNA, the phosphate group binds to the of the next group. 5.) The 5' end of a single DNA strand contains a free, while the 3' end contains a free. 6.) DNA was not thought to be the gene;c blueprint originally; instead many scien;sts hypothesized that contained the gene;c code and blueprint of life. (They were later proven wrong.) 7.) DNA is a type of (what type of organic molecule?). 8.) In order for DNA to replicate, (what kind?) bonds are broken. This is catalyzed by an enzyme called. The adding and joining (covalent bonding) of new nucleo;des (during the process of replica;on) is catalyzed by an enzyme called. This enzyme also catalyzes proofreading as new nucleo;des are added (it tries to make sure that C pairs with G and A pairs with T). 9.) Number the steps of DNA replica;on in the correct order (1, 2, 3) Daughter strands are formed using complementary base pairing. DNA unwinds The DNA of the daughter strands winds with together with its parent strand. 10.)What enzyme unwinds are unzips the parent strand? 11.)What enzyme synthesizes the new DNA strand? 12.)The two sides of the DNA helix are held together by 13.)You are studying a DNA (double helix) molecule that is 1,000 base pairs long and 20% of the molecule consists of thymines. a. How many total bases are in this double helix? b. What percentage of the bases are guanines? c. How many of the bases are guanines? d. Would you be able to answer this ques;on if the DNA molecule were single- stranded, instead? Explain. 14.)What makes DNA replica;on semiconserva;ve? 6
Objective 8: List the steps of mitosis and both describe and draw what occurs in each step. Use the information in the video clip and your textbook to fill in the following table: Stage Substage Drawing with labels Description (using vocabulary on page 2 of packet) Interphase G0 Not necessary G1 Not necessary S G2 Not necessary Mitosis Prophase Animal cell Metaphase Anaphase Telophase (including cytokinesis) General description: In plants: In animals: 7
Mitosis Practice: 1. Visit the following website: http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html a. Read the website s text. b. This site includes a collection of 36 pictures of 36 different cells. Look at each picture (micrograph), and decide which stage characterizes which picture. As you look at each picture, keep track of your data in the table below. (Place a tally mark in the appropriate box as you look at each picture.) c. When you are done looking at all 36 picture, calculate the % of the cells in each stage, and then infer the number of hours (in a 24-hour day) a cell spends in each stage. Interphase Prophase Metaphase Anaphase Telophase Total Number of cells 36 Percent of cells 100% # of hours out of a day 2. Look at the following pictures and label each one with the appropriate stage of mitosis. 24 hours a. b. c. 3. Label each of the following statements as being descriptive of interphase, prophase, metaphase, anaphase, or telophase: a. chromosomes are not yet visible b. sister chromatids have just broken away from each other at the centromere c. nuclear membrane is reforming d. sister chromatids are still attached to each other at the centromere, but chromosomes haven t lined up yet e. nuclear membrane is breaking down f. chromosomes have lined up in a single file line g. the stage that includes cytokinesis h. organelle replication and protein synthesis occurs i. in terms of changes in the nuclear membrane, this stage is the opposite of prophase 8
4. Observe the cell shown below (it has just finished cytokinesis) and make each of the six single chromosomes below a different color. a. Then, diagram how this cell would appear if it were seen in each of the following stages. Be sure that each diagram shows the shape of the cell, whether or not the nucleus is visible, and the chromosomal arrangement of the cell. b. Finally, write a caption for each diagram using words/phrases (where appropriate) such as sister chromatids, homologous chromosomes, centriole, and centromere. a. prophase of mitosis b. anaphase of mitosis 5. Used in chemotherapy treatments, taxol is an anti-cancer drug, which is known to stop cells from dividing. a. Tumors are clusters of cells that are growing and dividing without proper regulation. What is the difference between a benign tumor (non-cancerous), and a malignant tumor (cancerous)? b. How do you think taxol might work? Write about two specific ideas that you have. In other words, what mitotic processes might taxol prevent, and how would stopping these processes prevent effective cell division? (There are many, many possible answers here; the important part is that you apply specific knowledge about the cell cycle.) 9
Objective 9: Describe the major differences between cancer cells and normal cells and how the cell cycle may be altered in cancer. Why are tumors harmful? - - - What are Carcinogens? - To be cancerous, a cell must gain the ability to: Grow in the absence of growth stimulatory signals: Grow in the presence of growth inhibitory signals: Avoid the process of apoptosis: Become angiogenic: Proliferate indefinitely: Invade and metastasize: 10
Angiogenesis: Telomerase: Metastasis: 1. Cancer is always genetic. This means that cancer is caused by mutations in the DNA. So, a genetic mutation is a mutation (or change) in your DNA molecule. Because your body has evolved to have many back-up systems, cancer is almost always caused by a series of mutations, not just one. a. Is cancer a genetic disease? Is cancer necessarily an inherited disease? b. Are these genetic mutations always inherited mutations? c. Is an inherited mutation always a genetic mutation? d. Are genetic mutations always passed from one generation to another? e. Why do you think that cancer is generally considered a disease of aging? f. Why do you think that some people do have cancer at younger ages? 11