Biosc&0150:&Foundations&of&Biology&I.& & Review3:&&Chapter&7& &Adel,&Anthony,&Kathleen,&Megan,&Dr.&Swigonova& & Page&1&of&8&Review&Chapter&7:&The&cell&1. Prokaryotic&Structure:&a. The& shape& of& a& prokaryote’s& chromosome& is& _______________,& while& the& shape& of&eukaryotic&chromosomes&is&________________.&Circular,&linear&b. Explain&why&it&is&necessary&for&the&chromosome&of&a&prokaryote&to&be&highly&coiled&within&the& cell.& When& stretched& into& linear& form,& a& prokaryo te’s& chrom o so m e& can & be& up& to& 500&times&the&length&of&the&cell&itself.&Su pe rco iling&of&the&chromoso m e&with&th e&aid&of&enzyme s&allows&the&chromosome&to&fit&within&the&cell.&c. What& is& a& plasmid?& What& purpose& doe s& a& plasmid & serve& in& a& bacterial& cell?& Are& plasmids&essential& to& bacterial& survival?& A& plasmid& is& a& stretch& of& D NA& that& contains& genes& and& is&physically& independent&from& the& main& chromosome,& does& no t& c a rry & e ss e n ti a l& fu n c ti o n s & to &cell& survival.&Plasmids&serve&as& a u xilia ry &genes&and&m ay&contribute&to&adaptation& to&changed&environmental& conditions& (commonly& carry& resistan ce& genes).& Plasm id s& are& exch an ge a b le&between& different& bacterial& cells& and&disseminate&genes&throughout&and&among&bacterial&populations.&Scientists&often&m anipulate&bacteria&by&injecting&them&with& certain&plasmids,&as&you&will&learn&in&Biology&0060.&d. What& is& the& purpose& of& a& bacterial& cell& wall?& What& is& its& m a in & structura l& comp o n en t ?&Bacterial&cell&walls&give&added& support&to& the& cell.&Because& the& inside&of& a& bacterial&cell&is&usually&hypertonic& to&its& environment,& water&enters&the&cell&via&osmosis&through&the&plasma&membrane.&The&cell&wall&prevents&the&cell&from&bursting&due&to&the&influx&of&water.&The&main&component&of&bacterial&cell&wall&is&peptidoglycan.&2. Explain&how&the&pulseTchase&experiment&is&done.&&It&consists &o f&two&p a rts ,&t h e &“ p u ls e” &and&th en&the&“chase.”& For& the& “p ulse,”& the& cells& to& be& experimented& on& are& exposed & to& high& concentrations& of&labeled&mo lec u le s&(can&be&radioa ctiv e &leucine &for&amine &acids) &for&a&br ie f&time .&Then ,&large&amo u nt s&of&unlabeled&versions&of&the& same&m olecule& are&added& for&the&“chase.”&The&point& of&this& is&to& have&a&molecule&you&can&actually&follow&over&time&and&see&where&it&ends&up.&&&a. Why& is& it& necessary& to& expose& the& experimental& cells& to& a& high& concentration& of& labeled&molecules&for&a&short&time?&If& you & were& to & use& a& lot&of& th e & labeling& molecu le ,& it & would& be&hard&to&tell&where&specific&populations&of&labeled&molecules&were&moving.&b. Using&the&logic&of&a&pulseTchase&experiment,&if&you&were& to &ra dioa ctive ly&lab el& pro teins& in& the &rough& endo pla sm ic& reticu lum,& where& m ight& yo u& find & them& after& several& min ute s?& & & In& the&several&minutes&after&labeling,&you &m ight&find& the&labe led&pro teins&in&th e&G olgi&app aratus&if&it&didn’t&travel&far.&c. Explain& the&path&a&protein&takes&when &it&goes&through&the&end om e m bra ne &system &from&the&start&of& its&synthesis& on&the& Ro ugh & E R&to& secretion.&(Use& the&terms& secretory&vesicles,&p lasma&membrane,&Ribosome,&Rough&ER,&and&Golgi&apparatus).&&Ribosomes&attached&to&the&Rough&ER&produce& protein& strands&that& need&to& be& processed& in& the& Rough&ER& and&eventually&reach&the& Golgi& apparatus& wh ere & they& are& further& pro cess ed & and& possib ly& labeled & with&carbohydrates&so&that&when &they&reach&the&secretory&vesicles,&they&can&be&directed&to&the&plasma&membrane&for&secretion.&&d. You&label&a&certain&protein&and&preform&a&pulse&chase&experiment.&You&waited&4&hours&and&went&to&check&on&the&cell,&only&to&find&that&none&of&the&proteins&you&labeled&are&present.&What& might& have& happened?& & You& probably& waited& too& long& an d& after& four& hours,& the&protein& went& through& the& Rough& ER,& the& Golgi& apparatus,& and& eventually& was& probably&secreted&out&of&the&cell&so&you&couldn’t&find&the&labeled&protein&in&that&cell.&Biosc&0150:&Foundations&of&Biology&I.& & Review3:&&Chapter&7& &Adel,&Anthony,&Kathleen,&Megan,&Dr.&Swigonova& & Page&2&of&8&3. True&or&false&T&if&the&statement&is&false,&correct&it.&If&statement&is&correct&support&it&with&additional&informa tio n .&a. Cells&perform&specialized&functions&and&have&structures&that&suit&their&needs.&For&example,&muscle& cells& are& packed& with& mitochondria& to&produce&ATP&and&specialized&proteins&that&take&part&in&muscle&contraction.&The&reason&of&cell&functional&and&structural&diversity&is&that&they&differ& in& th eir& ge no m ic& D NA .&False.&An&organism’s&DNA&is&the&same&throughout&its&entire&body.& The& difference& between& certain& cell& types& arises& when& certain&genes& are& selectively&and&differentially&expressed.&b. A&fat& cell&w ould&be&expected&to& contain&a&large&amount& of& smooth& endoplasmic&reticulum&(ER).&True.&SER&is&the &site &of &fat&metabo lism.&c. On&the&scale&of&a&cell,&gravity&has&a&small&effect&on&movement&of&molecules.&&False.&Gravity&has& no& effect& on& the& movement& of& molecules.& Electrostatic& attractions& dominate& at& the&cellular&and&atomic&level.&&4. Does&the&nucleus&of&a&eukaryotic&cell&have&a&single&or&double&membrane?&Double&An&opening&into&the&cytosol&from&the&nucleus&is&called&a&___________________.&&&Nuclear&pore&The&___________________________&is&selective&for&letting&certain&molecules&enter&the&nucleus.&&It&is& m a d e& up& o f& (a& few/20/o ve r& 50)& d iff ere n t& proteins & and& f o rm s & an& e lab o ra te & structure.& It& allo w s &certain&molecules&to&enter&the&nucleus&if&they&have&the&prop er&____ _____ ____ ____ _____ ____ _.&The&rate& at& which& m o lec ules & ente r& and & lea ve& th e& nu cleus& is& ___________________.& & Nuclear& pore&complex,&over&50,&nuclear&localization&signal,&rapid&Which&of&the&following&is&most&likely&to&enter&the&nucleus&through&a&nuclear&pore&complex?&A.&DNA&B.&small&molecules&C.&really&large&molecules&that&have&nuclear&localization&sign a ls&D.&mRNA&Answer:&C&&5. Why&is&it& that&energy&is&required&to&move&proteins&through&a&cell&while&ions&and&amino&acids&do&not?&Ions& an d & amino& ac id s & a re & s mall& mo le cu le s & t h at & c a n & d iff u se & r a n d o mly& thro u ghout& a & c ell,& however&proteins& are& large& molecules& that & are& regu la te d & in& whe re & the y& m us t& go & so&