BIOL 1201 Study Guide: Exam 4-Fall 2013Chapter 11: Cell CommunicationUnderstand the different mechanisms for long distance and short distance signalingLong distance signaling: will involve hormones entering the blood streamShort distance signaling can involve: cell-cell junctions - gap junctions in animal cells, plasmodesmata in plant cellscell-cell contact - paracrine signaling: chemical signaling between cells very close to each other synaptic signaling: paracrine signaling involving neuronsUnderstand the processes of reception, transduction, and responseReception: physical interaction between ligand and receptorTransduction: series of signaling events that transmit signal from membrane to interior of cellResponse: cellular charge that results from the signalUnderstand where receptors are typically located for polar versus nonpolar ligandsPolar ligands can’t cross plasma membrane, so receptors are located on the plasma membraneNon-polar ligands can cross plasma membrane, so receptors are located in cytoplasm or nucleusUnderstand the mechanisms for G-protein coupled receptor signalingG proteins are enzymes because they have GTPase activity. They are capable of breaking down GTP into GDP+P. When these G proteins are bound to GTP, they are activated or ON. When bound to GDP, they are inactivated or OFF. So they toggle between off and on which will either turn the signaling pathway on or off.Understand the mechanisms for tyrosine kinase receptor signalingTwo different ligands bind to two different receptors on the plasma membrane. This causes these receptors to unite (dimerization). Which activates the kinase enzyme in the receptors, andthey phosphorylate each other, triggering a signaling pathway.Understand the mechanisms for ligand-gated ion channelsLigand binds to the receptor, which also functions as a protein ion channel. Ligand binding causes receptor to change shape and open a gate allowing ions to cross the membrane.Understand the mechanism for intracellular receptor signalingInvolves non-polar ligands (usually hormones). Hormones cross the plasma membrane and bind to receptors in the cytoplasm forming hormone-receptor complexes. These complexes can act as transcription factors and enter the nucleus, bind to DNA, and directly control gene expression.Understand the role of protein kinases and phosphatasesKinases: add phosphate group to substrate (phosphorylation). Generally activates substrate.Phosphates: remove phosphate group from substrate (de-phosphorylation). Generally deactivates substrate.Understand the role of Ca2+ and cAMP as second messengersBoth are very powerful 2nd messengers because they are capable of activating multiple different signaling pathways, so their concentrations inside the cell must always be regulated. cAMP is produced by the enzyme Adelyl Cyclase while Calcium is stored (sequestered) inside themitochondria, the ER, the nuclear envelope, and the extracellular fluid.Chapter 12: Cell CycleKnow how daughter cells produced by mitosis are different than daughter cells produced by meiosisMitosis: produces 2 daughter cells that are identical to each other as well as the parent cellMeiosis: produce 4 daughter cells that are not identical to each other or the parent cellUnderstand how somatic cells are different than gametesSomatic cells: your normal body cells (Diploid: 46 in humans). Gametes: your sex cells, sperm and egg (Haploid: 23 in humans)Know what process produces sister chromatids, where they are attached to other, and what role they play in mitosisDNA replication during S phase of interphase produces sister chromatids. They are attached to each other at the centromere. One chromatid from each pair of ends up in each of the daughter cells produced by mitosis.Be able to list what happens during the different stages of the cell cycle- Interphase: G1, cell grows. S, DNA copies itself. G2, cell grows more- M Phase: Mitosis (division of nucleus) Cytokinesis (division of cytoplasm)Have a general understanding of what occurs during the 5 stages of mitosis1. Prophase/Prometaphase: nuclear envelope breaks down. Chromosomes condense. Mitosis spindle begins to form.2. Metaphase: Sister chromatids line up at the metaphase plate (equator) of the cell, facing in opposite directions3. Anaphase: Sister chromatids separate and get pulled to opposite poles of the cell. Cell elongates.4. Telophase/Cytokinesis: Cleavage furrow forms in animal cells, cell plate in plant cells, cytoplasm splits. Nuclear envelope re-forms. Daughter cells are produced. Understand the role of the mitotic spindle, microtubules, and kinetochores during mitosis- Mitotic spindle: similar to a spool of kite string. Physically separates chromosomes. - Microtubules: similar to actual string. Attach to the chromosomes and spindle and separates the chromosomes- Kinetochore: like “handles” on the chromosomes. Located next to the centromeres and this is the attachment point for the microtubulesUnderstand what type of offspring are produced by binary fissionBinary fission is a form of asexual reproduction in some prokaryotes. It produces offspring that are genetically identical to parent cell, which produces very little variation in offspring.Know where each checkpoint occurs during the cell cycle and what types of proteins control each checkpoint1. G1: just before the S phase of interphase2. G2: just after S phase, before M phase3. M: just before cytokinesis in M phaseCyclins and Cyclin Dependent Kinases (CDK’s) control each checkpointChapter 13: Meiosis and Sexual Life CyclesUnderstand how sexual and asexual reproduction differ from each otherSexual: produces offspring that are genetically different from the parent cell Asexual: produces offspring that are genetically identical to the parent cellUnderstand what a karyotype would look like in both somatic cells and gametesSomatic cells: 22 pairs of autosomes, 1 pair of sex chromosomes (XX in females, XY in males)Gametes: 22 autosomes and 1 sex chromosome (X in female-eggs, X or Y in male-sperm)Understand the relationship between homologous chromosomes and how they differ from sister chromatidsHomologous chromosomes: same length, same genes, control same characteristics. Within eachpair, one chromosome came from mom and one from dad. Contain same genes but aren’t identicalSister chromatids: identical copies of individual chromosomes that are produced during S phase of cell cycle, in which chromosomes are replicatedKnow how many
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