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Study Guide: Cell Cycle/ Mitosis/ Meiosis Remember some of this information we have not covered in class yet! What is DNA? DNA is the genetic (heredity) material that contains all the instructions for an organism to develop. What are chromosomes? Chromosomes are the DNA when it condenses around the histones (proteins) and becomes visible. What is the difference between chromatin and chromosomes? Chromatin is DNA (pasta) that is not condensed and can’t be see easily especially during Interphase. Chromosomes are DNA that can be seen because they wind around histones and condense. Prokaryotes (bacteria) reproduce differently than eukaryotic cells. What is the process called when bacteria split into 2? Bacteria reproduce asexually by binary fission, they produce two identical cells. They do NOT go through mitosis or meiosis. Explain how viruses reproduce. How is this different from prokaryotic cells? How is this different from eukaryotic cells? Viruses reproduce by taking over a living cell, they can’t reproduce on their own like prokaryotic or eukaryotic cells. Viruses are NOT considered to be living both prokaryotes and eukaryotes are living organisms. Using your notes on cell cycle and mitosis answer the following questions: Why is the cell cycle process important? Cell cycle is important because it allows cells to grow, develop, reproduce and repair old and worn out cells. What are the 3 main stages of the cell cycle? a. Interphase b. Mitosis c. Cytokinesis What happens in each of the following phases of interphase? Explain in detail what is happening. G1 cell performs its function (job), cell continues to grow, cell stores up ATP, organelles multiply and produces proteins. S synthesis of DNA (DNA is copied) G2 cell grows, stores more ATP, does function, cytoskeleton prepares for mitosis What is the main purpose of mitosis? The process of mitosis assures that each cell will receive the correct amount (or number) of chromosomes. Mitosis is the division of the nuclear material to each daughter cell. Below identify the four main phases of mitosis. Explain what happens in each phase. Identify each stage below with a diagram. a. Prophase: chromosomes become visible, centrioles start to move, spindle fibers begin forming, nuclear membrane starts to break down and the nucleolus disappears b. Metaphase: chromosomes move to the center of the cell (metaphase plate or equatorial plate) and line up. c. Anaphase: the sister chromatids separate by the action of the spindle fibers, chromatids move to opposite sides (poles) of the cell d. Telophase: two nuclei start to reform in ONE cell, spindle fibers disappear, centrioles move back to same side of cell, nuclear membranes start to reform, nucleolus will reform and the cell may start to cleave (pinch off) What is cytokinesis? Division of the cell’s cytoplasm into two cells Explain how cytokinesis is different from mitosis. Mitosis is division of the nuclear material, (chromosomes) cytokinesis is division of the cell’s cytoplasm. When a cell reproduces, how does the number of chromosomes in the parent cell compare to the daughter cells? Explain your answer. The number of chromosomes in both daughter cells is identical to the parent cell. This insures that both cells will be able to grow through the cell cycle themselves. What is a karyotype? Karyotype is a picture of an organisms chromosomes from one cell. What are karyotypes used for? Karyotypes are used for identifying or diagnosing genetic disorders. A. B. What is the difference between the two karyotypes shown above? Karyotype B shows a person who is suffering or diagnosed with Trisomy 21. Down syndrome. Karyotype A is a normal male. How would you write the karyotype notation for the individual above in picture A? 46, XY (normal male) How would you write the karyotype for the individual in picture B? 47, XY,+21 Label the cells 1-5 in the order they would complete mitosis. 5 Telophase 2 Prophase 1 Interphase 3 Metaphase 4 Anaphase Identify each of the following cells as being in interphase, prophase, metaphase, anaphase, telophase or cytokinesis. Each term may be used more than one time or not at all. Metaphase Anaphase Telophase Telophase Metaphase Prophase Prophase Interphase What is the difference between somatic cells and gametes? Somatic cells are body cells (diploid) and gametes are sex cells (haploid) 1. What is cancer? The disease caused by an uncontrolled division (problems with the cell cycle) of abnormal cells in a part of the body. 2. A malignant growth or tumor resulting from uncontrolled division of cells. What are some causes of cancer? Chemicals, uv radiation, mutations in DNA and different types of viruses. What is the process of meiosis? Is the process by which ”gametes” (sex cells) , with half the number of chromosomes, are produced. Gametes are genetically different (diverse) from each other. Why is meiosis important to the survival of sexually reproducing organisms? If Meiosis did not occur the chromosome number in each new generation would double. The offspring would die. Example: sperm (46) + egg(46)= zygote (92) organism would NOT develop. Complete the chart below: Organism Number of chromosomes in somatic (body) cells Diploid (2n) Number of chromosomes in gametes (sperm and egg) Haploid (n) Cat 38 19 Goat 60 30 Horse 32 16 Dog 78 39 Meiosis 4 haploid daughter cells Mitosis 2 diploid daughter cells Mitosis (4 steps prophase, metaphase, anaphase and telophase) Types of Reproduction Meiosis I and Meiosis II Prophase I, metaphase I, anaphase I and telophase I then, Prophase II, metaphase II, anaphase II and telophase II Sexual Genetically Different (diverse) identical Cytokinesis After telophase Number of Divisions Occurs after telophase I and telophase II 2 Function Produce gametes Produce somatic cells Chromosome Number Haploid Diploid Crossing Over No Anaphase Number of Daughter Cells Yes, during prophase I when homologous chromosomes form a tetrad Anaphase I, split the homologous chromosomes, Anaphase II split sister chromatids 4 Creates Gametes, sex cells Somatic cells, all other cells Produces Steps Centromeres Split Asexual 1 2 What is crossing over? When homologous chromosomes (example: shoes) pair up and form a tetrad, some of the genetic information from one chromosome and swap genetic material with the other chromosome. Why is crossing over considered positive or a good type of change? Because it allows chromosomes to change (genetic variation) and may give the organism a better chance at survival. Define the following terms: Mutations: change in DNA sequence Inversion: when a piece of material breaks off and reattaches in the opposite direction Deletion: piece of the DNA breaks off the chromosome Translocation: pieces of DNA from one chromosome switch with another non-homologous chromosome. This involves TWO different chromosomes. Duplication: a section of a chromosome as double the amount of information. Nondisjunction: when homologous chromosomes do NOT separate properly. A cell can end up with an extra chromosome or not enough chromosomes.