BIOE 1010 Final Exam Study Guide
BIOE 1010 Final Exam Study Guide BIOE 1010
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This 9 page Study Guide was uploaded by Sara Littlejohn on Thursday April 14, 2016. The Study Guide belongs to BIOE 1010 at Clemson University taught by Dr. Vladimir Reukov in Spring 2016. Since its upload, it has received 120 views. For similar materials see Biology for BioEngineers in Bioengineering at Clemson University.
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Date Created: 04/14/16
BIOE 1010-Final Exam Study Guide Red Text- This material will be on the exam Highlighted Text- key concepts or terms Module 6-1 Cell Signaling Cell Communication Responses: cells change their metabolism, their morphology, grow, die, migrate, adhere, or differentiate Signals: proteins, peptides, amino acids, nucleotides, steroids, fatty acid derivatives, to even dissolve gas molecules General Principles of Cell Signaling Reception: Information comes as the signal (primary messenger) and stimulates a target cell by binding to and activating a specific receptor Signal transduction: the receptor converts the primary messenger into a second messenger Response: the second messenger: o Activates cellular responses o Causes changes in gene expression Forms of Cell Signaling Autocrine: a cell targets itself o Produced by signaling cells that can also bind to the ligand that is released. o The signaling cell and the cell can be the same or similar cell Signaling across gap junctions: a cell targets a cell connected by gap junctions o Gap junctions are connections between the plasma membranes of neighboring cells. o These water-filled channels allow small signaling molecules, called intracellular mediators, to diffuse between the two cells Paracrine: a cell targets a nearby cell o Signal molecules diffuse locally o Example: neurotransmitters Endocrine: a cell targets a distant cell through the bloodstream o Endocrine signals originate in endocrine cells which are located in endocrine glands ( such as the thyroid gland, the hypothalamus, and the pituitary gland) o The ligands released in endocrine signaling are called hormones Types of Receptors: Internal Receptors o Hydrophobic signaling molecules typically diffuse across the plasma membrane and interact with intracellular receptor in the cytoplasm o Many intracellular receptors are transcription factors that interact with DNA in the nucleus and regulate gene expression o The ligand-receptor complex moves into the nucleus, then binds to a specific regulatory regions of the chromosomal DNA and promote the initiation of transcription Cell-Surface Receptors o Also known as transmembrane receptors, are cell surface, membrane-anchored proteins that bind to external ligand molecules o Spans the plasma membrane and performs signal transduction, in which extracellular signal is converted into an intracellular signal o Ligands that interact with cell-surface receptors do not have to enter the cell that they affect o Cell-surface receptors are also called cell-specific proteins or markers because they are specific to individual cell types Ion Channel-linked Receptors o Bind a ligand and open a channel through the membrane that allows specific ions to pass through o A ligand binds to the extracellular region causing a conformational change in protein structure allowing ions to pass through G-Protein-linked Receptors o Heterotrimeric G proteins have three subunits: alpha, beta and gamma o Signaling molecule binds a G-Protein-coupled receptor causing a GDP molecule associated with the alpha subunit to be exchanged for GTP o The beta and gamma subunits disassociate form the alpha subunit, and a cellular response is triggered. o Hydrolysis of GTP to GDP terminates the signal Enzyme-linked Receptors o Cell-surface receptor with intracellular domains that ae associated with an enzyme or the intracellular domain of the receptor itself is an enzyme o When a ligand binds to the extracellular domain, a signal is transferred through the membrane, activating the enzyme o Activation of the enzyme sets off a chain of event within the cell that eventually leads to a response Signaling Molecules Small Hydrophobic Molecules o Can diffuse directly across the membrane into the cell Water-Soluble Ligands o Polar o Bind to extracellular domain of cell-surface receptors Gases o Cause blood vessels to dilate Methods of Intracellular Signaling Phosphorylation o One of the most common chemical modifications that occurs in signaling pathways is the addition of a phosphate group to a molecule such a s a protein in a process called phosphorylation Second Messengers o Small molecules that propagate a signal after it has been initiated by the binding of the signaling molecule to the receptor Response to the Signal Gene Expression o Some signal transduction pathways regulate the transcription of RNA o Others regulate the translation of proteins form mRNA Increases in Cellular Metabolism o Adrenaline (epinephrine) is a hormone that readies the body for short term emergencies Cell Growth o Cells do not normally divide unless they are stimulated by signal from other cells o The ligands that promote cell growth are called growth factors Cell Death o Programmed cell death is called apoptosis o Apoptosis allows a cell to die in a controlled manner that prevents the release of potentially damaging molecules from inside the cell Module 6-2 Cell Proliferation: Growth and Division o A cell grows by performing an orderly sequence of events called the Cell Cycle. o The Eukaryotic Cell Cycle: o The cell consists of interphase and mitotic phase. o During interphase, the cell grows and the nuclear DNA is duplicated. o During the mitotic phase, the duplicated chromosomes are segregated and distributed into daughter nuclei. o The cytoplasm is usually divided as well, resulting in two daughter cells. o Mitosis is divided into five stages: 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase o Cell Cycle Checkpoints: o The cell cycle is controlled at three checkpoints: o The integrity of the DNA is assessed at the G1 checkpoint. o Proper chromosome duplication is assessed at the G2 checkpoint. o Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint. o Concentrations of cyclin proteins change throughout the cell cycle. o There is a direct correlation between cyclin accumulation and three major cell cycle checkpoints. o Also note the sharp decline of cyclin levels following each checkpoint (the transition between phases of the cell cycle), as cyclin is degraded by cytoplasm enzymes. o Cyclin-Dependent Kinases o Cyclins regulate the cell cycle only when they are tightly bound to Cdks o Cyclin-dependent kinases(Cdks) are protein kinases that, when fully activated o To become fully activated, a Cdk must bind to a cyclin protein and then be phosphorylated by another kinase o The levels of Cdk proteins are relatively stable throughout the cell cycle: however the concentrations of cyclin fluctuate and determine when Cdk/cyclin complexes form o Rb halts the cell cycle and releases its hold in response to cell growth o Cancer and the Cell Cycle o Apoptosis: physiological event o Role: to balance mitosis in all tissues o Intervenes in normal processes: embryogenesis, tissue remodeling o Highly researched in pathological states: neoplasm formation o Cell shrinks and condenses o No inflammatory response o Necrosis: pathological event o Result of acute injury o Typical of acute ischemia, infarct, sudden deprivation of blood supplies o Cell swells and bursts o Results in damaging inflammatory response Module 7 Integrating Cells Into Tissues The Cytoskeleton o A dynamic structure continuously reorganized o Built from three types of protein filaments Actin Filaments (Microfilaments) Microtubules Stiff hollow tubes formed by the polymerization of tubulin They can rapidly disassemble in one location and reassemble in another, growing out from the centrosome During cell division, microtubules form the mitotic spindle, the machinery that will segregate the chromosomes equally between the two daughter cells Intermediate filaments Ropelike fibers (polymers) with great tensile strength Function: to withstand mechanical stress that occurs when cells are stretched Built from: keratin in epithelial cells, vimentin in fibroblasts and muscle cells, neurofilament in nerve cells, and nuclear lamins in the nucleus o Gives cells the ability: To adopt a variety of shapes To organize many processes inside the cell ( ex. Mitosis, organelle traffic) To interact mechanically with the environment To carry out coordinated movements Microtubules and motor proteins are involved in organelle traffic in the cell o Kinesins and dyneins: motor proteins that use the energy from ATP hydrolysis to move along the microtubules and carry specific membrane vesicles and other cargoes Actin Filaments: o Two stranded helical polymers of actin o Dispersed throughout the cell, highly concentrated in the cortex o Assemble and disassemble in cell locomotion Cell crawling depends on actin o Protrusion: actin polymerization at the leading edge of the cell pushes the plasma membrane forward o Attachment: new points of anchorage are made between the actin filament and the surface o Traction: contraction of the rear of the cell draws the body of the cell forward During contraction actin filaments slide against myosin filaments Muscle contraction depends on bundles of actin and myosin Tissues The extracellular matrix: an intricate network of macromolecules filling the extra cellular space Proteoglycans and GAGs form a highly hydrated gel-like “ground substance” in which the fibrous proteins are embedded and cells are held together Macromolecular composition of ECM o Two main classes: Polysaccharide chains: glycosaminoglycan (GAGs), usually fund covalently linked to protein in the form of proteoglycans Proteins with structural and adhesive functions: Collagen Elastin Fibronectin Laminin ECM forms o Calcified in rock-hard structures: bone, teeth o Transparent: cornea o Ropelike organization that gives tendons their enormous tensile strength o Flexible, thin tough mats around or under the cells: basal lamina (basement membrane) Role of matrix components o Polysaccharide gel resists compressive forces on the matrix while permitting the rapid diffusion of nutrients, metabolites, and hormones between blood and the cells o Collagen fibers strengthen and help organize the matrix o Rubberlike elastin fibers give resilience o Adhesive proteins help cells attach to matrix The collagen triple helix ( a unique 3-D structure) o 1 Collagen molecule = 3 Helical Chains that wrap around one another, due to a specific repeating tripeptide unit: Gly-Pro-Hyp Collagen molecules (tropocollagen) are cross-linked together to form collagen fibrils. Fibrils aggregate and form fibers. Cell Adhesion Molecules (CAMs) o Cadherins (cell-cell) are linked to the cytoskeleton o Integrins (cell-matrix) are linked to the cytoskeleton Cell junctions hold cells together in TISSUES TISSUES = CELLS + EXTRACELLULAR MATRIX (ECM) Tissue Classification o Connective Tissue Binds structures and fill spaces Cells: fibroblasts, macrophages, mast cells Provides support and protection o Epithelial Tissue Covers organs and the body Lines body cavity Cells tightly packed Functions: protection, secretion, absorption o Muscle Tissue Skeletal Muscle (attached to bones) Smooth Muscle (walls of organs and blood vessels) Cardiac Muscle o Nervous Tissue Found in brain, spinal cord, and peripheral nerves Neurons and neurological cells o Cells form Tissues o Tissues form Organs o Organs form Organ Systems
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