Chapter 11 Reading Guide PDF

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BIO Chapter 11 Reading Guide and Study Guide...

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Chapter 11 Reading Guide: Cell Division The targeted reading is created to guide your study, directing your attention to the content that will help you meet the learning objectives. There are detailed Learning Objectives at the end of the document if you need extra guidance. The answers to the Self-Assessment Questions are also included.

11.1 Cell Division (p. 225-227) During cell division, a single parental cell produces two daughter cells. LO 11.1 Describe the process and products of cell division. Terminology: Cell division: the process by which a parent cell gives rise to two daughter cells Asexual reproduction: the reproduction of organisms by mitotic cell division or fragmentation. Offspring are clones of the parent. Sexual reproduction: the process of producing offspring that receive genetic material from two parents; in eukaryotes, the process occurs through meiosis and fertilization. Gametes: a reproductive haploid cell; gametes fuse in pairs to form a diploid zygote. Eggs and sperm are an example. Binary fission: the process by which cells of bacteria or archaeons divide to form two daughter cells. Mitosis: The division of the nucleus, in which the chromosomes are separated into two nuclei. Cytokinesis: the division of the cytoplasm into two separate cells Cell Cycle: the name for the steps that make up eukaryotic cell division. M Phase: The stage of the cell cycle consisting of mitosis and cytokinesis, in which the parent cell divides into two daughter cells. Interphase: The time between two successive M phases. S phase: The phase of interphase in which the entire DNA content of the nucleus is replicated. G1 phase: The gap phase in which the size and protein content of the cell increase and specific regulatory proteins are made and activated in preparation for S-phase DNA synthesis. G2 Phase: The gap phase in which the size and protein content of the cell increase in preparation for M-phase mitosis and cytokinesis. G0 Phase: The gap phase in which cells pause in the cell cycle between M phase and S phase; it may last for periods ranging from days to more than a year. Figures: ● 11.1 Binary Fission ● 11.2 The Cell Cycle Self-Assessment Questions: 1. How is cell division similar and different in prokaryotic cells and eukaryotic cells? Eukaryotic cells divide by mitotic cell division. The first step is replicating their chromosomes in the nucleus. The nuclear envelope dissolves and each pair of chromosomes is separated. After the two sets of chromosomes are separated, a nuclear envelope forms around each one. Then the cell splits into two new daughter cells. Prokaryotic cells reproduce by a process called binary fission in which the cell replicates its DNA, increases in size and divides into two daughter cells that each have a copy of the parental DNA. Binary fission is similar to mitosis because a parent cell produces two daughter cells and the daughter cells are identical to each other and the parent cell. The processes differ because bacteria have circular chromosomes whereas eukaryotes have linear chromosomes. Another difference is the DNA in prokaryotes is attached to the plasma membrane which allows separation of DNA by cell growth, but eukaryotic cell’s chromosomes are not attached to the nuclear membrane.

2. What do you predict would be the consequence of a mutation in FtsZ that disrupts the function of the protein it encodes? If a mutation disrupts the function of FtsZ, it would block cytokinesis and cell division.

11.2: Mitotic Cell Division (p. 227-231) Mitotic cell division produces genetically identical daughter cells and is the basis for asexual reproduction and development. LO 11.2 Describe the processes that occur during mitotic cell division. Terminology: Karyotype: A standard arrangement of chromosomes, showing the number and shapes of the chromosomes representative of a species. Homologous: Describes characters that are similar in different species because of descent from a common ancestor. Haploid: Describes a cell with one complete set of chromosomes. Diploid: Describes a cell with two complete set of chromosomes. Sister chromatids: The two copies of a chromosome produced by DNA replication. Centromere: A constriction that physically holds sister chromatids together; the site of the attachment of the spindle fibers that move the chromosome in cell division. Prophase: The stage of mitosis characterized by the appearance of visible chromosomes. Mitotic spindle: A structure in the cytosol made up predominantly of microtubules that pull the chromosomes into separate daughter cells. Centrosome: A compact structure that is the microtubule organizing center for animal cells. Prometaphase: The stage of mitosis in which the nuclear envelope breaks down and the microtubules of the mitotic spindle attach to chromosomes. Kinetochores: the protein complexes on a chromatid where spindle fibers attach. Metaphase: The stage of mitosis in which the chromosomes are aligned in the middle of the dividing cell. Anaphase: The stage of mitosis in which the sister chromatids separate. Telophase: The stage of mitosis in which the nuclei of the daughter cells are formed and the chromosomes uncoil to their original state. Contractile ring: In animal cells, a ring of actin filaments that forms at the equator of the cell perpendicular to the axis of what was the spindle at the beginning of cytokinesis. Phragmoplast: In dividing plant cells, a structure formed by overlapping microtubules that guide vesicles containing cell wall components to the middle of the cell. Figures: ● 11.3 Human karyotype ● 11.4 Homologous chromsomes and sister chromatids ● 11.5 Mitosis, or nuclear division o Animation: Mitotic cell division ● 11.6 Kinetochores ● 11.7 Cytokinesis or cytoplasmic division Self-Assessment Questions: 3. Which DNA sequences are more alike: a pair of sister chromatids or a pair of homologous chromosomes? SIster chromatids are more alike because they have identical DNA sequences. Homologous chromosomes are inherited from two different parents. 4. What are three situations in which mitotic cell division occurs? Maintenance and repair of organs and tissues, asexual reproduction of unicellular eukaryotes, and the development of multicellular organisms.

5. What are the five stages of mitosis? Draw the structure and position of the chromosomes at each stage. 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase

6. What would be the consequences if a cell underwent mitosis but not cytokinesis? It would become a single cell with two nuclei and twice the normal amount of DNA. 7. How does cytokinesis differ between animal and plant cells? In animal cells, cytokinesis involves a contractile ring that forms against the inner face of the cell membrane at the middle of the cell. The ring contracts and the cytoplasm is pinched in half and forms two new daughter cells. In plant cells, cytokinesis involves the growth of a new cell wall called a cell plate in the middle of the dividing cell.

11.3 Meiotic Cell Division (p. 231-238) Meiotic cell division produces genetically unique daughter cells and it the basis for sexual reproduction. LO 11.3 Explain the purpose of meiotic cell divisions. Terminology: Meiotic cell division:  A form of cell division that includes only one round of DNA replication but

two rounds of nuclear division; meiotic cell division makes sexual reproduction possible. Meiosis I:  Reductional division; the first stage of meiotic cell division, in which the number of chromosomes is halved. Meiosis II: Equational division; the second stage of meiotic cell division, in which the number of chromosomes is unchanged. Prophase I: The beginning of meiosis I, marked by the visible manifestation of chromosome condensation. Synapsis: The gene-for-gene pairing of homologous chromosomes in prophase I of meiosis. Bivalent:  A four-stranded chromosomal structure formed in prophase I of meiosis composed of a pair of homologous chromosomes, each consisting of two chromatids, paired side by side and held together by one or more chiasmata. Non-sister chromatid: Chromatids of different members of a pair of homologous chromosomes; although they carry the same complement of genes, they are not genetically identical. Prometaphase I:  The stage of meiosis I in which the nuclear envelope breaks down and the meiotic spindles attach to kinetochores on chromosomes. Metaphase I: The stage of meiosis I in which the meiotic spindle is completed and the bivalents move to lie on an imaginary plane cutting transversely across the spindle. Anaphase I: The stage of meiosis I in which the two homologous chromosomes of each bivalent separate as they are pulled in opposite directions, but the sister chromatids remained joined at the centromere. Reductional division: An alternative name for meiosis I, since this division reduces the number of chromosomes by half. Telophase I:  The stage of meiosis I in which the chromosomes uncoil slightly, a nuclear envelope briefly reappears, and in many species the cytoplasm divides, producing two separate cells. Prophase II: The stage of meiosis II in which the chromosomes in the now-haploid nuclei recondense to their maximum extent. Prometaphase II: The stage of meiosis II in which the meiotic spindles attach to kinetochores on chromosomes. Metaphase II:  The stage of meiosis II in which the chromosomes line up so that their centromeres lie on an imaginary plane cutting across the spindle. Telophase II: The stage of meiosis II in which the chromosomes uncoil and become diffuse, a nuclear envelope forms around each set of chromosomes, and the cytoplasm divides by cytokinesis. Equational division:  Another name for meiosis II because cells in meiosis II have the same number of chromosomes at the beginning and at the end of the process. Polar bodies: A small cell produced by the asymmetric first meiotic division of a primary oocyte. Zygote: The diploid cell formed by the fusion of two gametes. Figures:

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11.8 Prophase I of meiosis 11.9 Chiasmata 11.10 Meiosis I 11.11 Meiosis II o Animation: Meiotic cell division Table 11.1 Comparison of Mitosis and Meiosis 11.12 Comparison of Mitosis and Meiosis 11.13: Cytoplasmic division in females and males

Self-Assessment Questions: 8. In a human cell at the end of prophase I, how many chromatids, centromers, and bivalents are present? At the end of prophase l, there are 92 chromatids, 46 centromeres, and 23 bivalents. 9. What are three ways in which meiosis I differs from mitosis? In mitosis, centromeres divide and sister chromatids separate, which does not happen in meiosis l. In meiosis l, homologous chromosomes pair and cross over. 10. What two processes during meiosis result in genetically unique daughter cells? 1. Crossing over- occurs at random places along the chromosomes and creates unique genetic combinations. 2. Random alignment of the homologous chromosomes on the spindle in metaphase l, each nucleus receives a random combination of homologs.

11.4 Nondisjunction (p. 238-241) Nondisjunction results in extra or missing chromosomes LO 11.4 Predict the possible changes in chromosome number due to nondisjunction. Terminology: Nondisjunction: The failure of a pair of chromosomes to separate normally during anaphase of cell division. First-division nondisjunction: Failure of chromosome separation in meiosis I. Second division nondisjunction: Disjunction in the second meiotic division. Down syndrome: A condition resulting from the presence of an extra copy of chromosome 21; also known as trisomy 21. Trisomy 21: A condition resulting from the presence of three, rather than two, copies of chromosome 21; also known as Down syndrome. Klinefelter syndrome: A sex-chromosomal abnormality in which an individual has 47 chromosomes, including two X chromosomes and one Y  chromosome. Turner syndrome: A sex-chromosomal abnormality in which an individual has 45 chromosomes, including only one X chromosome. Figures: ● 11.14 Nondisjunction o Animation: Nondisjunction ● 11.15 Trisomy 21 ● 11.16 Symptoms associated with (a) Klinefelter syndrome and (b) Turner syndrome Self-Assessment Questions: 11. How does nondisjunction in meiosis I or II result in extra or missing chromosomes? Make a diagram to answer the question.

12. A male baby is born with the sex chromosomes constitution XYY. Both parents have normal sex chromosomes (XY in father, XX in mother). In which meiotic division of which parent did the nondisjunction take place that produced the XYY baby

Nondisjunction took place in the father because the father donates the Y chromosomes. It took place in the second meiotic division because that is when the sister chromatids of the X chromosome separate and the sister chromatids of the Y chromosome separate.

11.5 Cell Cycle Regulation (p. 241-244) The cell cycle is regulated so that cells divide only at appropriate times and places. LO 11.5 Explain why the cell cycle is regulated. Terminology: Cyclins: A regulatory protein whose levels rise and fall with each round of the cell cycle. Cyclin-dependent kinases: A kinase that is always present within the cell but active only when bound to the appropriate cyclin. Checkpoint: One of multiple regulatory mechanisms that coordinate the temporal sequence of events in the cell cycle. Figures: ● 11.17 Cyclins and cyclin-dependent kinases (CDKs) ● How Do We Know: Fig. 11.18 How is progression through the cell cycle controlled? ● 11.19 Cyclin-CDK complexes ● 11.20 Cell Cycle checkpoints ● 11.21 DNA damage checkpoint controlled by p53 Self-Assessment Questions: 13. What are the roles of cyclins and cyclin-dependent kinases in the cell cycle? Cyclins bind to and activate CDKs. The CDKs phosphorylate target proteins involved in promoting cell division. 14. What are three examples of checkpoints that the cell monitors before proceeding through the cell cycle? 1. The DNA damage checkpoint, which is active in the G1 phase and checks for DNA damage.  2. The DNA replication checkpoint, which is active in G2 and makes sure all DNA is replicated. 3. The checkpoint for spindle attachment to chromosomes, which is active before anaphase and ensures that all chromosomes are attached to the spindles.

11.6 Cancer (p. 245-247) Cancer is uncontrolled cell division that can result from mutations in genes that regulate cell division. LO 11.6: Identify the key features of cancer cells. Terminology: Oncogene: a cancer-causing gene. Proto-oncogenes: The normal cellular gene counterpart to an oncogene, which is similar to a viral

oncogene but can cause cancer only when mutated. Tumor suppressor:  One of a family of genes that encode proteins whose normal activities inhibit cell division. Figures: ● How Do We Know: Fig. 11.22 Can a virus cause cancer? ● 11.23 Multiple mutation model for the development of cancer ● 11.24 Visual Synthesis Cellular Communities o Cellular Communities: 3D Animation Self-Assessment Questions: 15. How do oncogenes, proto-oncogenes, and tumor suppressor genes differ from one another? Oncogenes are genes that cause cancer. Proto-oncogenes are genes that have the potential to cause cancer when mutated. A tumor suppressor gene blocks specific steps in the development of cancer. 16. What are two ways in which the function of p53 can be disrupted? It can be disrupted by a mutation in the p53 gene or by an inhibitor.

Detailed Learning Objectives 11.1. Describe the process and products of cell division. ● 11.1a. Explain how prokaryotes assure that a copy of their DNA is directed to both cells formed by binary fission. ● 11.1b. Describe the two fundamental processes in mitotic cell division in eukaryotes. ● 11.1c. Describe the events that occur in the stages of the cell cycle. ● 11.1d. Explain the conditions that result in cells entering G0 phase. 11.2. Describe the processes that occur during mitotic cell division. ● 11.2a. Explain how genomic DNA is packaged into chromosomes in eukaryotic cells. ● 11.2b. Describe the number of chromosomes and their naming conventions in human cells. ● 11.2c. Differentiate between homologous chromosomes and sister chromatids. ● 11.2d. Describe the chromosomal contributions made by each parent during fertilization. ● 11.2e. Explain how replicated chromosomes remain paired after S phase. ● 11.2f. Describe the events that occur during the stages of mitosis. ● 11.2g. Differentiate between the process of cytokinesis in animal and plant cells. 11.3. Explain the purpose of meiotic cell divisions. ● 11.3a. Establish the roles meiosis and fertilization play in increasing genetic diversity. ● 11.3b. Determine the effect of meiosis on chromosome number. ● 11.3c. Describe the transition of ploidy that occurs during fertilization. ● 11.3d. Predict the effects on chromosome number in each stage of meiosis. ● 11.3e. Differentiate between the events that occur in meiosis I and mitosis. ● 11.3f. Explain how genetic diversity is generated through the alignment of homologs and crossing over during meiosis. ● 11.3g. Compare and contrast the events occurring in meiosis II and mitosis. ● 11.3h. Provide an argument supporting the hypothesis that meiosis evolved from mitosis. ● 11.3i. Relate differences in the division of cytoplasm during meiosis to the production of eggs and sperm. 11.4. Predict the possible changes in chromosome number due to nondisjunction. ● 11.4a. Describe the effect of the failure of chromosomes to pair or separate properly during mitosis or meiosis. ● 11.4b. Predict the effects of nondisjunction during meiosis on chromosome number in gametes. ● 11.4c. Describe the detrimental effects of extra or missing chromosomes. ● 11.4d. Define the chromosomal makeup of individuals with Down Syndrome. ● 11.4e. Describe the effects of missing or extra sex chromosomes. 11.5. Explain why the cell cycle is regulated. ● 11.5a. Explain the function of cyclins and cyclin dependent kinases in regulating cell division. ● 11.5b. Relate the activation of CDKs to cell division. ● 11.5c. Predict the effects of altering specific cyclin-CDK complexes on progression through specific phases of the cell cycle. ● 11.5d. Relate the importance of cell cycle checkpoints to progression through stages of the cell cycle. ● 11.5e. Describe the role of p53 in regulating the cell cycle. 11.6. Identify the key features of cancer cells. ● 11.6a. Explain how improper regulation of the cell cycle can cause cancer. ● 11.6b. Evaluate the role of viruses carrying oncogenes to the development cancer. ● 11.6c. Explain the relationship between viral oncogenes and cellular proto-oncogenes. ● 11.6d. Describe the specific cellular functions that are regulated by oncogenes and proto-oncogenes.

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11.6e. Describe the role of tumor suppressor genes in cancer. 11.6f. Explain why multiple mutations are required to cause cancer....