Chapter 6-Concept 6.1Though usually too small to be seen by the unaided eye, cells can be complex.Scientists use microscopes to visualize cells.Light Microscope (LM): Visible light passes through specimen.-MicroscopyMagnification: Ratio of object’s size in an image compare to in’s original sizeResolution: Image ClarityContrast: Visible differences in parts of a sample.-Electron MicroscopyTwo types of Electron MicroscopesScanning Electron Microscope (SEM): Focus’ beam of electrons on surface providing 3D like image.Transmission Electron Microscope (TEM): Focus beams of electronsthrough a specimen.Used to study mainly internal structure of a cell-Cell FractionationTakes cells apart and separates the major organelles from each other.Ex: CentrifugesHelps to determine functions of organellesBiochemistry and cytology help correlate cell function and structure.-Concept 6.2 Prokaryotic Cells vs. Eukaryotic CellsProkaryoticOnly Bacteria and ArcheaNo NucleusDNA is an area called nucleoidNo Membrane Bound organellesEukaryotic CellsDNA in a nucleusMembrane bound organelles.Surface are relative to volume of a cell is critical.Surface are increase by a factor of n^2 and volume increases by a factor of n^3.-NucleusNucleus: Contains most of the cell’s genes and is usually the most conspicuous organelleNuclear Envelope: Encloses the nucleus separating it from the cytoplasm.Double membrane, lipid bilayerNuclear Pores: Regulate the entry and exit of molecules from the nucleus.Shape of the nucleus is maintained by the nuclear lamina, net like array of protein filaments.Chromatin: DNA and proteins of chromosomes are together, only when cellis not dividing.Nucleolus: located within the nucleus and is the site of ribosomal RNA synthesis.-Concept 6.4: The Endomembrane system regulates protein traffic and preforms metabolic functions in the cell.1) Nuclear Envelope2) Endoplasmic reticulum3) Golgi Apparatus4) Lysosomes5) Vacuoles6) Plasma Membrane-Related either through physical continuity or connected via transfer by vesicles.-Endoplasmic ReticulumAccounts for more than half of the total membrane in many eukaryotic cells, is continuous with nuclear envelope. Two parts1) Rough ER2) Smooth ER-Functions of smooth ER1) Synthesis of LipidsOils, phospholipids, or steroids2) Metabolizes carbohydrates.3) Detoxifies drugs and poisonsInduces proliferation of Smooth ER and associated detoxification enzymes.Liver cell’s use hydroxyl groups4) Stores calcium ions – seen in muscle cells-Functions of Rough ERBound ribosomes, produces proteins into the lumen of the ER (Secreted from cell)Pancreatic Beta cells produce insulin.Secretory proteins are glycoproteins (Proteins covalently bonded tocarbohydrates)Carrier proteins from ER in transport vesicles, proteins surrounded by membranes separated from proteins produced in cytosol.Membrane factory of cellProduces membrane proteinsEnzymes can assemble phospholipids from cytosolic pressure.-Golgi ApparatusFlattened membranous sacs called cisternaeDistinct polarity (Cis and Trans Region)-Cis: Packaging-Trans: TransportExtensive cells specialized in secretion functions.Functions 1) Modifies products of ERCarbohydrate component of Glycoproteins2) Manufactures certain macromoleculesPolysaccharides, none-cellulose polysaccharides3) Sorts and packages materialsSorted by molecular ID tags such as phosphorylation2 Models of substances move from Cis to TransVesicular transport model: Macromolecules from one cisternae to another by vesiclesCisternae maturation Model: Cisternae actually progress from Cis totrans face carrying and modifying their cargo-LysosomesMembranous sac of hydrolytic enzymes that can digest macromoleculesCan hydrolyze proteins, fats, polysaccharides and nucleic acidsEnzymes are produced in rough ERAcidic EnvironmentWill not work on membrane protein, found on lysosomes since their 3D structure protects them from enzyme attachment.Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, in a process called autophagy.A human liver cell recycles it’s own macromolecules once a week.Lysosomes fuse with food vacuoleLysosomal Storage disease: rare, lack functioning hydrolytic enzymes in lysosomes.Tay-Sachs disease- lipid digesting enzyme missing or inactive resulting in a build up of lipids in brain cells-Causes Mental retardation and childhood death.-VacuolesFood Vacuole: PhagocytosisContractile Vacuole: Water removing pump found in some prokaryotic CellsCentral Vacuole: found in many mature plant cells; holds organic compounds and water.-Endomembrane systemComplex and dynamic player in cells compartments and organization.-Concept 6.5: Mitochondria and chloroplasts change energy from one form to another.Mitochondria: Cellular respiration uses oxygen to generate ATPChloroplasts: Found in plants and algae, are the sites of photosynthesis.Peroxisomes: Oxidative organelles-Evolutionary origins of Mitochondria and ChloroplastSimilarities to bacteriaDouble membraneFree ribosomes and circular DNA moleculesGrow and reproduce somewhat independently in cellsHave proteins made up by free ribosomesEndosymbiont theoryAncient Eukaryotic cell engulfed prokaryotic cell causes an Endosymbiont relationship.Merged into a single cell.Mitochondria and Chloroplast-MitochondriaSmooth outer membrane and inner membrane folded into cristae.Composed of phospholipids2 Compartments1) Inter-membrane space2) Mitochondrial MatrixSome metabolic steps of cellular respiration are catalyzed in the mitochondrial matrixmDNA, ribosomes and enzymes that catalyze cellular respiration reside in the mitochondrial matrixCristae present a large surface area for enzymes that synthesis ATP.More mitochondria mean more metabolic activity.-Chloroplasts: Capture of light energyThe chloroplast is a member of a family of organelles called plastidsChloroplast contains the green pigment chlorophyll as well as enzymes and other molecules that function in photosynthesis.Chloroplasts is found in leaves and grass.Structure:Double membrane with intermediate SpaceThylakoids, membranous sacs stacked to form granumStroma: internal fluid of the chloroplast surrounding outside of thylakoidsDNA, ribosomes and enzymes
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