Chapter 11Wednesday, November 4, 20158:04 AMCell SignalingIon-channel Receptors-Important in the nervous system-Lead to changes in sodium and calcium signal1. Signal molecule (ligand) binds onto ligand-gated ion channel receptor within the plasma membrane layeroChannel has a gate that is closedoIons floating outside of plasma membrane2. Gate opens afteroIons go through channeloIons get through to the cell - cellular responseoInitiates the transection state-Open or close in response to a chemical signal3. Gate closesoTransient - not lasting forever Two locations - cell membrane and few of them are located inside the cellIntracellular receptors Intracellular Receptors-Located within the cell-Requires signal molecules to go into the cell-Small, nonpolar/hydrophobic molecules-Ex. Testosterone-Can diffuse through the phospholipid bilayer-Once in the cytosol-Binds to receptor protein-Binding changes the conformation of the receptor protein to be recognized by nuclear pore complex-Allow protein to be imported-Act as transcriptional factor-Turns on and off transcriptions for DNA-mRNA is transcribed-Transported out of nucleus and translated into proteins Signal molecules- first messenger Second messengers-Certain small molecules and ions are key components of signaling pathwaysoCyclic AMP-Based on the structure of AMP-Modified AMPoCalcium ions and inositol TriphosphateCyclic AMP-Acts as a second messenger-Produced from ATP by the enzyme adenylyl cyclaseoEnzyme catalyze the production of AMP from ATP-PhosphodiesteraseoBreaks covalent bond between oxygen and carbonoReturn cyclic AMP to regular AMP Q. Adenylyl cyclase has the opposite effect of ___a. Phosphodiesteraseb. cAMPc. Tyrosine Kinase receptord. GPCRe. calcium At time = 0 seconds, + serotonin At time = 20 seconds -Produced and quickly spread from thenew cell-cAMP levels 20 seconds after serotonin treatment Calcium Ions and Inositol Triphosphate-Maintain low calcium concentrationoCalcium pumps on membraneoCalcium pumps on ERoCalcium pumps on mitochondria-So oriented that they pump- Cytosol has low calcium concentration Q. Which is not a second messengera. cAMPb. Calciumc. IP3d. Epinephrine (first messenger - stops at cell membrane)e. None of the above -1st messenger binds to receptor-GPCR activates G protein = GTP-Activates its enzyme (phospholipase C)-Once activated (PC) it will scan the membrane and find a special lipid (POP2) and cut off the IP3 from the membrane lipid-IP3 is a second messenger small molecule that can quickly diffuse through the cell-IP3 diffuses out the celloCalcium channel - CA2+ (second messenger)oDiffuse from higher to lower concentration-Lumen to cytosoloCalcium diffuse through to bring about cellular responses-Can be done by tyrosine-An inhibitor of which factor could be used to block the release of Ca++ from the ER?oIf we block IP3 or G protein, first messengers, epinephrine, phospholipase C (direct one),calcium channel we can block the release, GPCR (turn off), tyrosine kynase receptor - we also block the calcium release Nuclear Response-Phosphorylation cascade-Where they will phosphorylate-Bind to DNA and activate gene-mRNA Q. Which of the following will most likely to be an immediate effect of growth factor binding to receptor?a. Protein kinase activityb. GTPase acitvity (haven't been discussed)c. Photophotase activity (haven't been discussed - opposite of kinase, remove phosphate group from adenylyl)d. Adenylyl cyclase activitye. Phospholipase activity (not activated by growth hormone) MitosisWithin mitosis, cell takes a lot of time-Goes to M phase - division of nucleus Cytokinesis-In animal cellsoCytokinesis occurs by a process known as cleavage, forming a cleavage furrow to separate cytoplasmoCell membrane pinches inside to form a furrow, deeper and deeper until it separates into two daughter cells-Cellular kinesis is different between animal cells and plant cells-Plant cellsoMitosis-Prophase - chromatin is condensing, nucleolus is beginning to disappear, mitotic spindle starting to form-Prometaphase - nuclear envelope will fragment, discrete chromosomes consisting of two identical sister chromatids, spindle fibers attach-Metaphase - all chromosomes lined in equator of cell, no nucleolus/envelop visible, spindle is complete, chromasomes -Anaphase - kinetochore microtubele fibers shorten, split-Telephase - reverse of prophase, reappearing of nucleolusDeliver cell wall material to form cell plateoDuring cytokinesis-A cell plate forms-Carbohydrates are deposited to the middle of the cell to form the cell plate, as the plate grows, it completely separates mother cell into two daughter cells, the plate becomes the new cell wall Q. A cell with 92 chromosomes at metaphase of mitosis at the end of telophase, there will be 2 nucleiwith _ chromosomes each.a. 92 - chromosomes are x shaped, two sister chromatids, doubles the number of chromosomes, at anaphase, cells should have 184, telephase evenly divides into two nuclei = 92b. 46c. 23d. 16e. 184 Q. If there are 20 chromatids in the cell at metaphase, how many chromosomes will each daughter cells have after mitosis?a. 20b. 10 - at metaphase x shape, 2 chromatids, after mitosis-stelephase and cytokinesis - the amount should be the samec. 30d. 5e. 40 Q. Which of the following occurs during mitosisa. Uncoupling of the chromatids at centromere - anaphaseb. Synthesis of DNA - S-phase of interphasec. Synthesis of protein - G2, some cells also during G1 if main task is making insulin, endocrine celld. Separation of cytoplasm - cytokinesise. Formation of cell plate - cytokinesis of plant cell Binary Fission (Prokaryotes - Bacteria)-Binary fissionoThe bacterial chromosome replicatesoThe two daughter chromosomes actively move apart-Repel each other, move towards opposite poles-They are separated as they are synthesized-Cell cycle control (internal factors)oThe frequency of cell cycle varies from cell to celloDetermine when and how fast the cell can divide-Evidence for Cytoplasmic SignalsoMolecules present in the cytoplasm-Regulate progress through the cell cycle-The Cell cycle control systemoThe sequential events of the cell cycle-Are directed by a distinct cell cycle control system, which is similar to a clock-At checkpoints,The clock has specific checkpoints where the cell cycle stops until a go-ahead signal is receivedWithout a signal, the G1 phase exits the cell cycle and goes into G0 phase, a non-dividing state-The Cell Cycle Clock: Cyclins and