Chapter 4: General Features of Cells PDF

General features of cells cell theory - : > - ALL Living things are madeupofone ormore cells. > cells are thesmallest - building blocks of Life > New cells - arecreatedfromexisting cells throughcell division...

General features of cells cell theory - : > - ALL Living things are madeupofone ormore cells. > cells are thesmallest - building blocks of Life > New cells - arecreatedfromexisting cells throughcell division Microscopy · Most cellsaretoosmallwithout a microscope. · Microscope helpscientists seethe structure andfunctionofcells uses electron beam resolution forLuminatina factors in using microscope- : · Magnification- how much biggertheimageappears comparedto the actualsize. · Resolution-the obilityto see 2 close objects as separate anddistinct - >Ig - S jjj5. Contrast- how clear a cellstructurelooks compared to others, whichcan be improvedwithdyes, · Prokaryotic cells - prokaryotess simple cells without nucleus · , watersoil, humanbodies) They are much smallerthanenkorystic cells andfound in everywherelair - - Bacteria-very common, mostly harmless - Archaea- Less common, usually found inextreme environments - Bothtypes of prokaryotes aresmall insize The cellstructure: ALL PrRonyotic cells contain: Additional in some: (outsideinthe wall) · - CLLWALLo CoPsuLer - - cell membrane - Plasmids : - CytoPLaSmo - fLageLo - DNA o - Pilio - Ribosomes. - membrane infolding  Structure of prokaryotic > - cell(cell envelope) The cell emlope of prokaryoticcell includes Plasmamembrane, cell wall, and LYCOCALY Plasmamembrane(innerLayer) - : > Double - LayeroP f hospholipids , Similar to euraryotic cells. > It - controls what enters andexits theCells CeLL WaLL (outerLayer- : > - made ofo tough material called peptidoglycan(mixofsugarsand peptides) >It help the cellto keep it's shape, - Whetherit's round(cocus), Rashaped(bacillus), orspiral > Some - bacteria, like mycoplasmadon't havecellwall,they don't havefixedshape. > Bacteria is classified as - gram-positive orgram-negative based ondifferences intheircellWall ELycoCalyx (outside CeLLWALL) - : > - sticky layerof sugaroutsidethe cellwall. It helps to protect > - bacteriafromdrying out, defends against the immunesystem, Let's bacteriastick tosurfaces (teeth, rocks, orothercells) > - It secretedfrom insidethe cell and forms athick,sticky coating outside, Cell envelope(glycocalyx or capsule) · The glycocaly(orcapsule whenfrimly attached · Itsheilds the bacteriaandis common in harmful bacteria it's a protective lateraroundsome bacteria because it blocks white bloodcells fromattacking them. · capsules iftheYeocalyx is tightly attached · It's madeof starch or geyeslipids. · It · stime layers iftheCLYeoColy is Loosely attached helps bacteria avoiddrying out(desition) · It's a wellorganized layermade of polisachorides· · It hidesthe bacteria fromthe immunesystemand protects themfromviruses · It also helps bacteriatostickto surfaces. Prokaryotic cell structure - prokaryoticcells have no nucleus. - Insteadsthey havea regioncalled nucleoid, where DNA floats the Cytoplasm They have a single, circularchromosome - - Therede no histone proteins bound to the DNA , it's often called NakedDNA & bacteriaisnot boundto special proteins  Prokaryotic plasmid > - Plasmids-some bacteria havesmallercircularPieces of DNA. > - Itcontain resistance genes that can be passed to otherorganisms > - It carry non-essentialsenes(not necessary forbasic survival >It - can replicate independently of mainchromosome DNA. Ribosome in prokaryotes · prokaryotic libosomes aresmallerthanlibosomes ineukaryotic Cells · · > made upof 2parts, sosubunit and sos subunits 70s libosomes - · Theirmainjob is to makeproteins forthe cell. Structure of prokaryotic cell(cytoplasm) cytoplasm-semi-fluidinside thecell, surfunded by Plasma membrane· ing - - It contains enzymes needed forthe bacteria's metabolismo - Thesinglechromosome is formd in a gel-likearea callednucleid - Therearemany ribosomesthat help make proteins - Inclusionbodies are storage areas for substances, like nutrients, which bacteriacan use when needed Structure of prokaryotic cell(appendages) Bacteria can have several types of appendages- : > - Flagella : - > - fimbrine: - > - Long tail-linestructures that help bacteria move. , -small hair likefibersonthe surface of the cell. > - They rotate likea motorunderthe Plasmamembrane. > - Notformoving but forattackingto surfaces. many flagella indifferent spots >Bacteria can havefor - > Sex Pili : - - > Tube-like structures that allow bacteria to Pass DNA from one cellto another - > Even - though bacteria repreduceby binary fission,they can exchangeDNA throughthesePilio  Eukaryotic cells · · · In enroyotic cells, DNA stored insidethe nucleus These cells are organized into different compartments called organelles organelles- small structureswith specificfunctions· · animal CeLL Plant Cell · Theshape,size, and organizationof cells can bevery different betweenspecies and even betweendifferent cell types inthe some organism. Proteome determines characteristics of a cell - A single organism canproducedifferent types ofcells howeverall cells havethesame DNA. - proteome-thedifference comes fromeachcell having a uniqueset of proteins - The Proteomedetermines acell'sstructureandfunction - factors like serveregulation, amount of proteinproduced,sequenceofamino acids, and protein modifications can effect a cell's proteome - The proteome inhealthy cells is differentfromthoseinconcerous cells The proteome refersto thesetof proteinsthat are actively made inacellat acertaintime, under - aspecific conditions· Cytosol The stoplasm of enrarbotic cell is the areabetweenthe organees n > Plasma membrane· and > It - includes everything insidethePlasmamembrane, suchas CytosL CeLL (fLuidPart), endomembranesystem, semiautonomous organelles· Metabolism cytosolisthe mainareawhere many important metabolic activities happen in eukaryotic cells includes - : · catabolismsthe process of breaking down molecules into smaller Ports · and macromolecules · Anabolism- the process of building up largermolecules and cellular components· CeLL  Cytoskeleton - The Cytoskeleton acts as the internalsupport systemof the cell. - It maintains the cell's shope,strengthens it, helps with movements, and holds organelles in Place. Microtubules : - - Long,tube-likestructures madefromalphaand betatubulinproteins. - The alphaand betaprimpand form sheets thatfold into cylinders - Microtubules have a polarstructure witha plus and minus end - They growandshrink inaprocess called dynamic instability: Importantfunctions: - - moving organelles Like mitochondriaorvesicles insidethe cello - supporting ciliaandflagella(formovement) - Helpingto devide cells during mitosis. - Buildingthe cellwall in plantso Intermediate filaments : - - movestable than microtubules and activfliments (they don't breakdownorrebuild easily - Help maintainthe cell's shapeandrigidity by handling tension. - found inthe cytoplasm, nucleus, and also outside the cellto help bind cells together - madefrom proteins like Relatin Actinfilaments(microfilaments) : - - made of 2twisted chains ofactivprotein. - supportthe Plasma membraneandgive the cell strengthand shope - Involved in connecting cells to othercells orthe surrounding structured - playing a role in Processes Like Phagosytosis (engulfing particles) and providetensilestrength Cytoskeleton function Microflimantes : > Help maintain cellshape - microtubules: > - Aid incytoplasmicstreaming, circulating the cytosolso > - Assist inchromosome separationduring cell devision, all organelles get access to nutrients especially during anaphase identical copies of chromosomes process of cell division > - Play role in cytokinesis (cell division) in animal cells > wor - withcentromeres toPulLapart sisterchromatids. Intermediatefliments: > - Help with cellmovement,formingPorts offLogeLLa > cotribute to - forming stabletissues. and ciliceo structures on surfaceof some enraryotic cells (similarto flagella) > since - they can extendoutsidethecell,they assist in cell-to-cell interactions  Motor proteins · motorproteinsare special proteins in cells that uses ATP forenergy to helpwith movement They havesports> head, hinge, and tail · To explain how motorproteins Worr/LikeWorking) : - · ground is cytoskeletalfilament · · yourleg is head of motorprotein. · yourhip is hinge. ways motorproteins can move: · The motorproteinwalks along thefilament, carrying congo to anotherLocation(like Kinesin) · The motorproteinstays in placeandpushesthefilament to move(like myosin) · The motorprotein andfilament are bothstuck, but proteinstill tres to walr cousing filament to bend(like dinein) · They convert chemicalenergy fromATP into movement energy by breaking downATPo Motor proteins(flagella and cilia) emaa zillum a Flagella is usually - longerthancilia and appearaloneorinPairs onacello · Treble cilia is shorterthanflagellaand often coverpart wallof cell's surfaces - Dynein - Both havethesome internalstructure. Structure of flagellum - They containmicrotubules, dinein, andanarrangementcalled axoneme - Microtubules are arrangedin192 Potter19 Pairs around2 centralmicrotubules - Theirmovement happens by a bending motionthat starts at the base and moves towald thetipo Nucleus > - Nucleoplasmtthe nucleus contains chromatin in a semi-fluids > - Before thecelldivides, cromatincondenses into chromosomes > chromatinis made of DNA, Proteins, and SomeRNA -. > it's a double membraneconterand innerthat separates the > Nuclearenvelope- - nucleus from CytOPLaSmo > Nuclearpores allow proteins andRNA to move betweenthe nucleusandestoplasmo - >The nucleus - main job is to protect, organize, andexpressgenetic material > - assembled inthe nucleus. Ribosomes are > - Nucleoplasm is thefluid insidethenucleus  Endomembrane system. > network of membranes that includes nucleus, Endomembrane system- · endobcosmicreticimsgolgiapparatus,sosomes, vacuoles, and Plasmamembrane · These membranes may be directly connectedorrass materials betweenthem CeLL usingvesicles. · This system helps to keepcertainchemical reactions limitedtospecificareas withinthe cello Nuclear envelope - The nucleorenvelope is made of2 membranes that surround thenucleusa - membrane is connectedto the endoplasmicreticulum The outer - Nuclearpores act asgateways, allowing materials to move inand out of the nucleus. - However, the materials insidethe nucleusoneseparatefromendomembranesystemo Endoplasmic reticulum > - > a networkof membranes that formtube-likestructures EndoplasmicVeticulum(ER) - called cistereo > ER Lumen- - > insidespace , ER is connected to the outenuclear membrane > Rougher has - ribosomes attachedto it and helps moreandsort proteins. >It also modifies proteins - by adding corbohydrate chains and helps foldthem into theirfinalshape. > SmoothER - doesn't haveribosomes and is involved in detoxifying chemicals, monaging conbonstrates,storing calcium, andmaking andmodifying Lipids. Golgi apparatus (also called golgibody orgolsi complex) · Golgi apparatus - > it's a stck offlot, membrane-bound compartments separated from ERo · > one is facing ER, theotherfaces Plasmamembrane In animal cells- · · It modifies proteins andLipids,thenpackagesthem intoresides fortransport. It has3 mainjobs : - · secretion- releasing materialfromthecello · processing- > changing proteins andLipids · > sending themtothe right place. sorting-  Lysosomes - Lysosomes- > de membrane-boundvesides madeby golgi apparatus. - They have lowph and containstrong digestive enzymes (acidhydrolasses) to breakdownproteins, carbohydrates, nucleicacids, andLipids - They digestfoodparticles and harmful invaders likeviruses orbacteriathroughendocytosis. >Lysosome Autophagy- also breakdownworn-out organelles bythis process - - The Lysosome's membrane protectstherest ofthecellfrom Powerfulenzymes inside,otherwise it causedamage - Lysosomes are involvedinthecell's selfdeathprocess Vacuoles vacuoles havedifferent functions depending ontypeof celland environmental conditions - : > - > Central vacuoles store nutrients and providesupport In Plant cells- In > - > contractice vacuoles help removeexes water protists- >In protistsandwhite blooacells- - > phagocyticvacuoles helpbreakdownordecrade harmful materials Peroxisomes · Peroxisomes->they aresmallorganellesfound in alleuralyticCeLLs · · Theirmainfunction is to speedupcertainchemical reactions, usually thosethat breakdownby removing(H) oradding(0) Hydrogen Peroxide(H202) process : · Long fatty acids choing toxin ↓ B-oxidation · RH2402- > R4H202 short mediumfatty acidchains ↓ · It's quickly brokendowninto waterand oxygenbyonenzymecolLedCatalases Mitochondria d · Peroxisomes havedifferentenzymes depending onthecelltype. CO24H20 · In livesthey help to produce bilesolts fromcholestrol and breakdown fats Plasma membrane - Acts as a barerbetweenthe cell and it's surroundings Controls whatenters andexits thecello - - Helps cells to communicateusing special receptors - Allows cells to sticktogether  Semiautonomous organelles > - They called"semiautonomous" because they candivide ontheir > While - Billywi through fission, producing moreof themselves own they have some independence, making some oftheirown proteins and · containing theiowngeneticmaterial, butstill rely onthe cellforcertainrecourses and most proteins. > Mitchondriaand ChLOOPLASES > Examples- - Mitochondria · Mitochondra are responsibleforcellularrespiration corbondrates · > Co24H20(Adenosinetriphosphate) CH20 + O - · ATP is usedforalenergy needed in the cell. · MitochondriaProduce most ofthe cell's ATPand havea membranes- > outer membrane called cristal andfolded innermembrane. · Inside, the matrix contains enzymes that help breakdowncarbohydrates and nutrients. · Mitochondria also help withthe synthesis, modification,and breakdownof various molecules in thecello Mitochondria and chloroplasts MitochondriaandChloroplasts share2traits withbacterice : - - They havetheirownDNA, separatefromcell's nucleus, whichis small, circulardoublestranded chromosomesimilarto bacterialDNA - They reproduceby binary fission, meansthat theysplit into2, just Like bacteria Chloroplasts > - Photosynthesis happens inchloroplasts,where lightenergy is capturedandusedto makeorganic molecules likeaucose > - abones a solrenergy, co2He chloroplasts arefound inmost plants andolfeand aregreendueto the pigment Chlorophy/1 > - They have2membranes (innerand outerwithasmallspace betweenthem > -. > InsidetheChloroplast,the fluid is called stroma, itcontains enzymes· - >Inthestroma, there are stacks - ofthylakoids,whichit'sthesiteof Photosynthesis > - Thesestacks are calledgrandorganum·