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Unformatted text preview: ral and functional aspects of various specialized structures in prokaryotes and the basic mechanisms of prokaryotic motility. 1. Bacteria may have specialized internal structures for specific purposes, including thylakoids and carboxysomes for photosynthesis, gas vesicles for buoyancy, storage granules for energy, magnetosomes for oriented swimming, and endospores for surviving through stressful periods. 2. Surface structures are used for attachment (pili and stalks), molecular transfer (pili), or a specialized type of movement called “twitching motility” (type IV pili). 3. Flagella are rotary appendages used for movement. The flagellum is made up of a protein called flagellin. Rotation is driven by a complex of proteins embedded in the cell membrane that act as a motor. 4. Chemotaxis is the process of moving toward or away from a chemical. It consists of a biased random walk alternating between runs in a straight line and tumbles that change the direction of movement. The ratio of tumbles to runs is regulated by chemical receptors that “sense” attractants or repellants, and results in net movement toward attractants and away from repellants. 5. Multiple mechanisms of cellular motility are known, including swimming motility using flagella, swarming using flagella and surfactants, twitching using type IV pili, and gliding. !"#$%&$'&(#)*+,-.%,.-#+*&/*"01,1+2/,0#3%*%#''+*4*%2$/15$%,#-&$ ?2;:96<9b;K'?83R:8R3;? DHJ'8N/.1M"+,@ !"#13.$,%%&.3)7,7*3.#,')12.1)2(%+) -"@7,#1' !-"@7,#1')$.-1&3,)%"@21 !%"@21)"')$(#A,31,+)"#1()BCD DTJ':1%\"W/@"$)@ !"#$%&'"(#)*(+",')-.$/,+)0"12)3&*"'$() 4,#567,8 !,#567,)9(3):;<)= >.?(# E+-'FGF_ DFJ'[email protected]'Q)@+0.)@'Y (%"$"*)'\A"/1#0/ !"#$%&'(")*%+%*,&(-&).(+%/0 !(0*,&#/.&'#0&)#11&#0$&0(+&2#+%.3&)%."#4*,&+(&#/.& 45+&0(+&2#+%. #6 6)%#'/#*/7%$&1+.5'+5.%1&/0&"#0,&8.(9#.,(+%1 DaJ'?*"%1-)'-%1#A.)@ D1J'O./0"-)#'-%1#A.)@ !"#$%&'()%#"*+ D\J'2"./L LN/,%"W/\A*/%1*) D2BSJ'1#,' 2"./L LN/,%"W/1.M1#"1*) -%1#A.)@ D0J'?A.&A%'-%1#A.)@ !"#$$%&'&()#*+$&,)+-)#&./01$#2/ 3#$+$/,$&,)+-)#&4)#2%5& *6717,816$,2,&95#$$%&7)1,24$&'& *)#*+$&2%,24$: D,J'2N"@(N1*)'-%1#A.)@ #" DXJ'!1-#)*"@"$)@ !"#$%&'(#)%*+(,)$'-(#./#) DIJ';#,"@("%)@'Y ,"%$1#*'@*%A0*A%)@' *N1*'1%)'N+-N./'%)@[email protected]*1#*'*"'@*%)@@)@ 0'&am...
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