BIOL 1201 Study Guide Exam 4 Fall 2013 Chapter 11 Cell Communication Understand the different mechanisms for long distance and short distance signaling Long distance signaling will involve hormones entering the blood stream Short distance signaling can involve cell cell junctions gap junctions in animal cells plasmodesmata in plant cells cell cell contact paracrine signaling chemical signaling between cells very close to each other synaptic signaling paracrine signaling involving neurons Understand the processes of reception transduction and response Reception physical interaction between ligand and receptor Transduction series of signaling events that transmit signal from membrane to interior of cell Response cellular charge that results from the signal Understand where receptors are typically located for polar versus nonpolar ligands Polar ligands can t cross plasma membrane so receptors are located on the plasma membrane Non polar ligands can cross plasma membrane so receptors are located in cytoplasm or nucleus Understand the mechanisms for G protein coupled receptor signaling G 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 signaling Two 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 and they phosphorylate each other triggering a signaling pathway Understand the mechanisms for ligand gated ion channels Ligand 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 signaling Involves 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 phosphatases Kinases 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 messengers Both 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 the mitochondria the ER the nuclear envelope and the extracellular fluid Chapter 12 Cell Cycle Know how daughter cells produced by mitosis are different than daughter cells produced by meiosis Mitosis produces 2 daughter cells that are identical to each other as well as the parent cell Meiosis produce 4 daughter cells that are not identical to each other or the parent cell Understand how somatic cells are different than gametes Somatic 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 mitosis DNA 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 mitosis 1 Prophase Prometaphase nuclear envelope breaks down Chromosomes condense 2 Metaphase Sister chromatids line up at the metaphase plate equator of the cell Mitosis spindle begins to form facing in opposite directions elongates 3 Anaphase Sister chromatids separate and get pulled to opposite poles of the cell Cell 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 microtubules Understand what type of offspring are produced by binary fission Binary 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 checkpoint 1 G1 just before the S phase of interphase 2 G2 just after S phase before M phase 3 M just before cytokinesis in M phase Cyclins and Cyclin Dependent Kinases CDK s control each checkpoint Chapter 13 Meiosis and Sexual Life Cycles Understand how sexual and asexual reproduction differ from each other Sexual produces offspring that are genetically different from the parent cell Asexual produces offspring that are genetically identical to the parent cell Understand what a karyotype would look like in both somatic cells and gametes Somatic 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 chromatids Homologous chromosomes same length same genes control same characteristics Within each pair one chromosome came from mom and one from dad Contain same genes but aren t identical Sister chromatids identical copies of individual chromosomes that are produced during S phase of cell cycle in which chromosomes are replicated Know how many autosomes and sex chromosomes are present in human somatic cells and gametes Somatic cells 44 autosomes 2 sex
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