Anatomy , Chapter 3

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Perixisomesdetoxify toxic substances: oxidase enzyme changes toxins to hydrogen peroxide, catalase enzyme breaks down hydrogen peroxideMicrotubulesSupport the cell and give it shape. Involved in intracellular and cellular movements. Form centrioles and cilia and flagella, if present.intermediate filamentsrope like protein fibers, helps cell resist mechanical forces on the cellMicrofilamentsstrands made of spherical protein subunits - involved in muscle contraction and other types of intracellular movement, help form the cell's cytoskeletoncentrosomesmicrotubule organizing center, contains centriolescentriolespart of the centrosome, form the basis of cilia and flagella, organize the microtubule networkthree parts to the cytoskeletonmicrofilaments, intermediate filaments, microtubulesciliaprojections formed by centrioles, moves materials across the cell surfaceflagellaprojections formed by centrioles, longer than cilia, propels the cell itself -Ex: spermMicrovilliprojections that increase the cell's surface area for absorptionNucleusControl center of the cell, responsible for transmitting genetic information and providing the instructions for protein synthesisnuclear envelopeA double membrane that surrounds the nucleus in the cell, controls the passage of substances to and from the nucleusnuclear poressmall holes in the nuclear envelopenucleoliSites where ribosomes are assembled, they center around the DNA that codes for rRNAchromatinmade of DNA, histone proteins, and RNA chainshistonesprotein molecules around which DNA is tightly coiled in chromatin, package and regulate DNAnucleosomes (Histone Octomer)8 histone proteins wrapped by 2 winds of DNA double helixFunctions of the plasma membrane-Physical barrier that separates the cytoplasm from the extracellular fluid -selective permeability - communication with chemical messengers - call recognition with other cellscomponents of plasma membranephospholipids, cholesterol, proteins, carbohydratesPhospholipids in plasma membraneform basic structure of membrane, hydrophobic tails on the inside to prevent substances crossing, hydrophilic head on the outsidecholesterol in plasma membranestiffens membrane, decreases water solubility of membraneProteins in plasma membranedetermines what function membrane can perform - transport, communicationintegral proteinsembedded in a lipid bilayerperipheral proteinsanchored on the side of the membrane or on other proteinstransmembrane proteins (channel proteins)Integral proteins that span the membrane, let substances go in and out the cellcarbohydrates in plasma membraneare bonded to a protein or lipid - are located on the outer surface of the plasma membrane called glycocalyx - glycolipids form when bond with lipid - glycoproteins form when bond with proteins2 major periods of the cell cycleinterphase and cell divisionInterphasecell carries out its routine activities and prepares for cell divisioncell divisiona cell divides into two new daughter cellsinterphase can be broken down into 3 subphasesG1 (gap 1): vigorous growth and metabolism S (synthetic): DNA replication occurs G2 (gap 2): preparation for divisionG1 phaseThe first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.S phaseThe synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.G2 phaseThe second growth phase of the cell cycle, consisting of the preparation for division.cell cycleseries of events in which a cell grows, prepares for division, and divides to form two daughter cellsmitotic phase of cell cycle consists of 2 distinct events:mitosis, cytokinesisMitosis (cell division)prophase, metaphase, anaphase, telophase____________ takes up most part of the cell cycleinterphasetonicityability of a solution to change the shape of cells by altering the cells internal water volumeIsotonic solutionscells retain their normal size and shape - the same amount of water is moving in and out of the cellhypertonic solutioncells lose water by osmosis and shrink - water moves outside the cell to the higher concentrationHypotonic solutioncells take on water by osmosis until they become bloated and burst - water moves inside the cell because it has a higher concentrationEndocytosistransport into cell Involves formation of protein-coated vesicles ▪ 3 different types: phagocytosis, pinocytosis, receptor-mediated endocytosisPhagocytosisCell eating - the cell eats a large particle by forming a projecting pseudopod around it and enclosing it in a sac called a phagosome . the phagosome meets a lysosome and it is digestedPinocytosisCell drinking - the cell gulps a drop of extracellular fluid into tiny vesiclesreceptor-mediated endocytosisExtracellular substances bind to specific receptor proteins, enabling the cell to ingest and concentrate specific substances in protein coated vesicles. substance may be released inside the cell, or combined with a lysosome to digest contents.Autophagy (self-eating)sweeps up unneeded stuff into vesicles, the vesicles then meet with a lysosome to digest the unneeded stuff.autophagy serves 3 roles-cells dispose of unneeded stuff -in starvation, it allows cells to eat themselves in order to survive -it helps restructure cells during developmentUbiquitin-proteasome pathwayhandles individual proteins that are misfolded, damaged, or unneeded and must be disposed of.______________ are doomed proteins marked for destructionubiquitins_______________ hydrolyze tagged proteins into small peptides and digest themproteasomesApoptosisrids the body of cells that are programmed to have a limited life span - caspases initiate apoptosis, cell shrinks into a ball and tells macrophages to "eat me"t SNAREplasma membrane snarev SNAREvesicle SNAREthe process of exocytosis1: Molecules in the vesicle that need to be secreted go to the plasma membrane 2: the v SNARES bind with the t SNARES at the plasma membrane 3: the vesicle and the plasma membrane fuse together and a pore opens up to release the contents in the vesicleTelomeresstrings of nucleotides that protect ends of chromosomes (like caps on shoestrings)Every time a cell divides, the telomere _________shortenstypes of Cell aging theories-wear and tear theory -mitochondrial theory of aging -immune system disordersimmune system disordersbody loses ability to fight pathogenswear and tear theoryas time goes by, repeated use and abuse of the body's tissues cause it to be unable to repair all the damagemitochondrial theory of agingdiminished energy production by damaged mitochondriaG-proteins and cell signaling steps 1-61. the ligand binds to a receptor and activates it outside the cell 2. the activated receptor binds with G protein and activates it in the cell 3. the activated G protein activates an effector protein by changing its shape 4. the activated effector creates reaction to produce 2nd messengers in the cell 5. 2nd messengers activate other kinase enzymes 6. kinase enzymes activate other enzymesG-proteins and cell signaling is like a game of _____________telephonegenesregions of DNA that code for proteinsCentral DogmaDNA -> mRNA -> ProteinDNA turns into mRNA by ________________ and mRNA turns into Proteins by _______________________transcription, translationDNA is replicated by the enzymes ________________ and _______________helicase, DNA Polymerase