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GSU BIOL 3800 - Final Exam Study Guide
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Biol 3800 1st EditionExam # 4 Study Guide *Review these important notes and key terms for test!Chapter 15- Cell Communication- Cells communicate with each other using signals- Signaling molecules illicit a specific response only in target cells thathave a receptor for that signal- Signals that cannot get through the cell membrane will bind to cell surface receptors Cell Surface Receptors– Integral Membrane proteins– 3 distinct domains• Exoplasmic• Cytoplasmic• Membrane-spanningThe cell surface receptor is a trans-membrane proteinSignal =LigandSignal Transduction= converting an extracellular signal to an intracellular responseParacrine- Signaling molecules released by a cell affect target cells in close proximity• Neurotransmitters• Growth factors– regulate developmentSignals and Receptors- Different cell types may have different sets of receptors for the same ligand- Each receptor can induce a different response- Different cell types may have the same receptor- Binding of a particular ligand to a particular receptor may trigger a different response in each type of cell- One ligand can induce different cells to respond in different waysReceptor-Ligand Complex• Measure of the affinity of the receptor for its ligand Kd dissociation constant• Maximum cellular response does not require the activation of all receptors• Sensitivity of the cell to the signal depends on the number of receptorsChapter 20- Cell CycleThe Cell Cycle• Two main molecular processes take place during the cell cycle– S-phase Chromosome duplication– M-phase Chromosomes are distributed to each daughter cell• Cell division is controlled by checkpoints that are in place to prevent initiation of a stepbefore the previous step is completeCell Cycle Phases• G1 (Gap): Between the end of mitosis and DNA synthesis for next mitosis– Most of the life of a typical cell• S (Synthesis): DNA replication; chromosomes copied• G2 (Gap): Between synthesis and mitosis; preparing for cell division• M (Mitosis): Chromosomes condense, spindles form, nuclear membrane dissolves,chromosomes migrate along spindles, cell divides, nuclear membranes reformRegulation of CDK ActivityThree key features about these kinases are important to keep in mind:• Cyclin-dependent kinases (CDKs) are only active when bound to a regulatory cyclin subunit.• Different types of cyclin-CDK complexes initiate different events. G1 CDKs and G1/S phase CDKs promote entry into the cell cycle, S phase CDKs trigger S phase, and mitotic CDKs initiate the events of mitosis• Multiple mechanisms are in place to ensure that the different CDKs are only active in the stages of the cell cycle they trigger.Mitotic cyclin-CDK complexes are synthesized during S phase and G2 , but their activities are held in check until DNA synthesis is completed Once activated, mitotic CDKs promote entry into mitosisTheir inactivation during anaphase prompts cells to exit mitosis, which involves the disassembly of the mitotic spindle, chromosome decondensation, the re-formation of the nuclear envelope, and eventually cytokinesis.Cycle Regulation• Surveillance mechanisms known as checkpoint pathways operate to ensure that the next cell cycle event is not initiated until the previous one has been completed.Chapter 25- CancerHallmark of a Cancer Cell• Cancer Cell– proliferates without external signal– Resistant to signals that inhibit cell division/cell death– Ability to move– Develop vasculature• Normal Cell– requires growth factors for cell division– Can halt the cell cycle or undergo apoptosis– Do not move without instruction. Loss of cellular regulationGenetic damage (mutation):1. proto-oncogenes2. tumor-suppressor genes3. caretaker genesCancer Genes• Proto-oncogenes– mutated version is an oncogene– involved in cell division, differentiation and cell death• Tumor-suppressor genes– Halt the cell cycle• P53• p16• Caretaker Genes– Protect the genome– DNA-repair enzymesOverview of Cancer All cancers result from the abnormal cell division and growth of cells• The dysregulation of growth results from permanent changes in gene expression (DNAmutations) in normal cells• Mutated genes frequently involve regulation of cell division, DNA repair• Mutations occur mostly in somatic cells, but some mutations occur in germ line• The cancer-forming process is an interplay between genetics and the environment.Important concepts and properties of cancerOncogenesis or tumorigenesis: the cancer-forming process.• Metastasis: a process that cells migrate from the primary tumor to new sites where they form secondary tumors• Benign tumor : Tumors that pose little risk to their host because they are localized, and of small size• Malignant tumor: their ability to invade nearby tissues and spread to distant onesMost cancer deaths are due to invasive, fast-growing metastasized tumorsGOOD


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GSU BIOL 3800 - Final Exam Study Guide

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