CH12 Study Guide NEW
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Montgomery College**We aren't endorsed by this school
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BIOL 150
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Biology
Date
Dec 18, 2024
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4
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CHAPTER 12 STUDY GUIDEBIOL150MITOSIS: THE CELL CYCLECell division3 purposes of cell division: 1.Growth 2.Repair and replacement 3.ReproductionCell cycleThe series of events that take place in a cell leading to its division and replication. Two main phases: Interphase and mitotic phase Interphase: G1, S, , G2 Mitotic Phase: M phase; Prophase, Metaphase, Anaphase, Telophase, CytokinesisConcept 12.1: Most cell division results in genetically identical daughter cellsMitosis vs. meiosisMitosis: creates identical cells for growth, repair, and asexual reproductionMeiosis: Creates genetically diverse gametes for sexual reproduction, ensuring genetic variation in offspring GenomeComplete set of genetic material (DNA or RNA) present in a organism or virus. It includes all the information needed for the growth, development, functioning, and reproduction of that organismChromosome structure- chromatin: The unwound, loose form of DNA and protein in the nucleus - sister chromatids: Two identical DNA strands formed after DNA replication, connected at the centromere - centromere: The central region where the sister chromatids are joined and where spindlefibers attach during cell division. Somatic cells vs. gametesSomatic cells are the body cells responsible for all functions except reproduction, and they have two sets of chromosomes Gametes are specialized reproductive cells with half the chromosome number of somatic cells and are involved in sexual reproduction Mitosis vs. cytokinesis Mitosis focus on the division of the nucleus and its chromosomeCytokinesis follows mitosis and is responsible for the division of the cytoplasm, completing the process of cell division and creating two distinct daughter cells 1
CHAPTER 12 STUDY GUIDEBIOL150Concept 12.2: The mitotic phase alternates with interphase in the cell cycleInterphase: Where the cell prepares for division1.G1a.Description: Cell growth, organelle duplication, protein synthesisb.Key events: increase in size, preparation for DNA replication 2.S phasea.Description: DNA replication b.Key events: Duplication of chromosomes, forming sister chromatids 3.G2phasea.Description: Final growth and preparation for mitosisb.Key events: Protein synthesis, checking DNA replication accuracy Mitotic Phase (M phase): Phase of the cell cycle where the cell divides its nucleus and cytoplasm to form two daughter cells 1.prophasea.Description: Chromosomes condense and spindle forms b.Key events: Chromosomes visible, nuclear envelope dissolves, spindle fibers form2.prometaphasea.Description: Spindle fibers attach to chromosomesb.Key events: Nuclear envelope fully dissolves, spindle fibers attach to kinetochores 3.metaphasea.Description: Chromosomes align at the cell’s equator b.Key events: Chromosomes line up along the metaphase plate, checked by the spindle 4.anaphasea.Description: Sister chromatids are pulled apart b.Key events: Centromeres split, chromatids move to opposite poles,5.telophase a.Description: Chromosomes decondense and nuclear envelope reforms b.Key Events: Chromosomes uncoil, nuclear envelope reform, spindle fibers disassemble6.Cytokinesisa.Description: Division of cytoplasm into two daughter cells b.Key events: Cleavage furrow (animal cells) or cell plate (plant cell) formsMitotic spindle: A structure made of microtubules and associated proteins that plays a critical role in the proper segregation of chromosomes during mitosis1.Centrosomesa.Description: Microtubule organizing centers at spindle poles.b.Key role in mitotic spindle: Form and anchor the spindle microtubules, positioning the spindle apparatus2.Kinetochoresa.Description: Protein structures on centromeres where spindle fibers attachb.Key role in mitotic spindle: Connect chromosomes to the spindle, ensuring accurate segregation 2
CHAPTER 12 STUDY GUIDEBIOL1503.metaphase platea.Description: Imaginary plane where chromosomes align at the cell’s equator during metaphaseb.Key role in mitotic spindle: Ensures proper chromosome alignment for equal distribution in daughter cells.Cytokinesis in animal cells vs. plant cells1.cleavage furrow a.Mechanism: Contractile ring creates a cleavage furrow that pinches the cell b.Key structures: actin filaments and myosin in the contractile ring c.Physical features: Furrow forms and deepens to split the celld.Rigid cell wall?: Absent, allowing membrane flexibility e.Outcome: Two daughter cells separated by the plasma membrane2.cell plate a.Mechanism: Vesicles fuse to form a cell plate that becomes the new cell wall.b.Key structures: Vesicles from the Golgi apparatus, microtubules.c.Physical features: A plate that forms and grows outward to divide the celld.Rigid cell wall?: Present, requiring a new cell wall to forme.Outcome: Two daughter cells separated by a new cell wall. Binary fission in bacteria: Primary method bacteria and many prokaryotes reproduces. Asexualprocess that results in the production of two genetically identical daughter cells. - origin of replication: The bacteria chromosome is circular and contains a specific sequence of DNA called the origin of replicationKey Functions:Serves as the starting point for DNA replication.Ensures that replication occurs in a precise and regulated manner.Plays a role in the attachment of the chromosome to the cell membrane during segregationConcept 12.3: The eukaryotic cell cycle is regulated by a molecular control systemCell cycle control system: complex network of regulatory proteins that ensures the orderly progression of the cell cycle and prevents error in cell division. Checkpoints : act as surveillance mechanisms to verify that key processes, such as DNA replication and chromosome alignment, are completed correctly before the cell moves to the nextphase.- G1checkpoint : determines whether the cell will proceed to DNA synthesis (S Phase) orenter a quiescent phase (G0) G0 phase: a reversible or irreversible resting state, cells in this phase do not divide but may remain metabolically active - G2 checkpoint (cyclin/Cdk/MPF): Ensure that DNA replication in the S phase has been completed accurately and that the cell is ready to enter mitosis (M phase) - M checkpoint: occurs during mitosis, specifically at the metaphase stage, to ensure proper chromosome alignment and spindle attachment before anaphaseExternal signals that influence cell division3
CHAPTER 12 STUDY GUIDEBIOL150-growth factors1.Definition: Proteins that stimulate cell division2.Significance : Regulate division based in physiological needs, suchas growth and repair -density-dependent inhibition1.Definition : Cells stop dividing when they become crowded 2.Significance: Prevents overgrowth and maintains tissue structure -anchorage dependence1.Definition: Cells must be attached to a substrate to divide 2.Significance: Ensure cells divide only in appropriate locations, maintaining tissue integrity. Cancer cells- transformation: Process by which a normal cell becomes a cancerous cell- benign tumor: mass of abnormal cells that remain localized and do not invade surrounding tissues- malignant tumor/metastasis: cancerous cells that invade nearby tissues and have the ability to spread to distant parts of the body (metastasis) 4