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Transcript
Cytoplasm HONORS ANATOMY & PHYSIOLOGY Cytoplasm material between plasma membrane& nucleus site of most cellular activity 3 elements 1. Cytosol 2. Organelles 3. Inclusions Cytosol viscous, semitransparent fluid in which other elements in cytoplasm are suspended complex mixture of: water proteins salts Sugars other solutes Organelles specialized cellular compartments or structures each has specific function Organelles non-membranous: cytoskeleton ribosome Endomembrane System membranes allow inside to differ from cytoplasm membranous: mitochondria, Ers, Golgi, lysosomes, peroxisomes intermembrane system: connections between ERs, nucleus Mitochondria structure dbl membrane inner membrane has enzymes used in etransport chain matrix w/in ↑ enzymes for citric acid cycle Function aerobic cellular respiration ATP Mitochondria Ribosomes Structure Function proteins + rRNA translation part of 2 subunits large small protein synthesis Ribosomes Endoplasmic Reticulum extensive system of interconnected tubes & parallel membranes enclosing fluid-filled cavities called cisterns continuous with outer membrane of nuclear envelope 1. Smooth ER 2. Rough ER Smooth ER Structure continuous with RER enzymes (integral proteins) Function metabolize lipids synthesize cholesterol & lipoproteins synthesize steroid hormones absorb, synthesize, & transport fats detoxify drugs, cancercausing chemicals glycogen free glucose SER RER Structure Function ribosomes stud surface synthesize all proteins of membrane proteins made on these ribosomes thread way into cisterns proteins then enclosed in vesicles Golgi exported from cell makes membranes RER Golgi Apparatus Structure Function stacked & flattened modifies,, membranous sacs associated with numerous vesicles concentrates, & packages proteins &lipids destined for export packages enzymes into vesicles lysosomes, peroxisomes Peroxisomes Structure Function “peroxide bodies” detoxify harmful membranous sacs substances (many in liver& kidney) breakdown & synthesize fatty acids containing enzymes ex: oxidases, catalases made in ER Lysosome Structure spherical, membranous organelles containing activated digestive enzymes in acid pH many found in cells that phagocytize plasma membrane has H+ pumps Function enzymes digest all molecules H+ pumps maintains normal pH in cytosol degrade worn out organelles glycogen glucose breakdown nonuseful tissues Tay-Sachs 1 enzyme missing in lysosmes of nerve cells buildup of glycolipid lysosomes swell with undigested lipids interferes with normal nervous system functioning death in early childhood Cytoskeleton “cell skeleton” network of protein rods thru cytosol supports cell structure allows cell movement Types: 1. Microfilaments 2. Intermediate Filaments 3. Microtubules Microfilaments Structure Function made of actin strengthens cell surface “web” just inside transmit force during plasma membrane of all cells movement & shape changes works with myosin muscle contractions & formation of cleavage furrow in cytokinesis Intermediate Filaments Structure Function tough, insoluble resist pulling forces protein fibers most stable & permanent of the 3 attach to desmosomes exerted on cell Microtubules Structure Function hollow tubes made of determine overall protein tubulin most radiate from centrosome very dynamic: selfassemble/dissemble have associated proteins that help organelles move in cytoplasm shape of cell distribute organelles https://www.youtube.c om/watch?v=4TGDPot bJV4 Centrosomes Structure Function made of paired generates & organizes centrioles: barrelshaped organelles oriented @ rt angles to each other microtubules organizes mitotic spindle Cilia Structure Function whip-like, motile as beat in unison cellular extensions found in large #s on surface of cell 9 paired microtubules runs length of cilium mucus/particles swept over surface of cell http://www.zoology.ubc.ca/courses/bio33 2/Images/Cilia/Cil3/cilium.gif Flagella Structure Function cell projections formed propels entire cell by centrioles longer than cilia only human cell with flagella is the sperm 9 + 2 pattern of microtubules http://worms.zoology.wisc.edu/dd2/echin o/fert/sperm/sperm.html Microvilli Structure Function minute projections of ↑ surface area plasma membrane on cell surface found on surface of absorptive cells have core of microfilaments (actin) Nucleus Structure Function dbl membrane houses chromosomes ~5 µm in diameter shape conforms to cell shape 3 regions: nuclear envelope nucleoli chromatin (DNA) making it the control center of cell Nuclear Envelope Structure Function selectively permeable dbl gives shape to nucleus membrane with nuclear pores outer membrane continuous with RER inner membrane lined with rod-shaped proteins that give shape to nucleus pores: complex of proteins pores allow transport route for substance in/out of nucleus encloses nucleoplasm (jelly-like similar to cytoplasm) Nucleolus Structure Function dark staining spherical assemble ribosomal bodies w/in nucleus subunits combine rRNA with proteins Chromatin Structure bumpy threads weaving thru nucleoplasm 30% DNA 60% histones (proteins which package and regulate DNA 10% RNA Function genome codes for proteins Chromosomes Structure Function DNA Codes for proteins Telomeres : DNA at protects chromosome either end of chromosome coding portion acting like “bumpers” Other Roles of DNA Iintrons (parts of pre-mRNA that stay in the nucleus) have role as other RNAs antisense RNAs: can block translation microRNAs: supress certain mRNAs made by certain exons riboswitches: folded RNAs that code for protein that include an on or off switch responding to metabolic changes in their immediate environment (change in environment induces change in configuration stopping or starting protein translation) Degradation of Organelles autophagy: “self-eating” cell debris swept into vesicles (autophagosomes) lysosomes for digestion rate increases in cell stress anoxia, high temp, lack of growth factors can lead to apoptosis (programmed cell death) Ubiquitins proteins that mark other proteins no longer being used by cell for destruction once marked hydrolyzed by proteosomes (giant waste disposal complexes) recycle a.a. and release ubiquitins Extracellular Material (ECM) any substance contributing to body mass found outside cells 1. Body Fluids 2. Cellular Secretions Body Fluids interstitial fluid 2. plasma 3. cerebrospinal fluid 1. Cellular Secretions gastric juices bile mucus sweat serous fluid Extracellular Matrix most abundant ECM = “cell glue” secreted by cells jellylike substance proteins + polysaccharides Apoptosis programmed cell death common in developing embryo: especially in nervous system carves out digits in developing hands, feet Hyperplasia accelerated division of cells Atrophy decrease in size of an organ or body tissue loss of normal stimulation muscles that lose their nerve supply atrophy & waste away Cell Aging still a mystery wear-and tear theory mitochondrial theory progressive disorders in immune system genetic theory: telomere clock