Biosc&0150:&Foundations&of&Biology&I.& & Review4:&&Chapter&8&&&9& & Adel,&Anthony,&Kathleen,&Megan,&Dr.&Swigonova& & Page&1&of&14&Review&Chapter&8:&Cell0cell&interactions&1. In&additio n &to&pla sma&memb r ane,&some&cells&also &co n ta in &primary&cell&wall.&What&is&the&function&of&the&primary&cell&wall?&The&primary&cell&wall&defines&the&shape&of&a&cells,&provides&structural&support,&and&protection.&&a. What&is&the&primary&structural&component&of&the&cell&wall&of&a&cell&extracted& from& corn,& mushroom ,& green& algae,& and& spider?& The&primary& component&of&the&cell&wall&of&is&cellulose&in&corn&and&green&algae&and&chitin&in&mushro om.&&Spider&is&an&insect&and&their&cells&do&not&have&cell&wall.&b. In&p la n ts ,& what&consequence&w ould&there&be& for&cells&if&their&primary&cell&wall&did& not&have&crossGlinked& ce llu los e & st ran d s ? & It& wou ld & n o t& b e & a s& s tr o n g& s o & it& would& b e& e a sie r& t o & d a m a g e & an d& it& would &have&difficulty&withstanding&the&force&that&water&exerts&on&it&via&turgor&pressure.&&c. What& is& the& purpose& of& pectins& in& the& primary& cell& wall?& & Pectin& is& the& gelatinous& po lysaccharide&between&micro& fibrils&that& ho lds&large& a m ou nts &of&w ate r&to&k ee p&a&c ell&wall&moist&an d&helps&keep& th e&structure&firm&by&holding&that&water.&d. Explain&how&the&primary&cell&wall&is&responsible&for&defining&the&shape&of&plant&cells.&The&primary&cell&wall&helps&de fin e& sh a p e&d u e &to &t u rg or &p re ss u re.& W h e n &c o nc e n tra tio n s& of &so lu te s &a re& hig h e r&in sid e &t he &cell&tan&outside,&water&enters&via&osm osis.&Th e&incom ing&w ater&inflates&the& plasma &m em brane,&w hich&exerts&a& force&against&the&primary&cell& w all.&T his& force&is&known&as& turgor&pressure.&So&thanks&to& this,&the&plasm a &membran e&is&pushed &against&the &p rim ary &cell&wall,&wh ich&is&what&defines&its&shape.&Th e&primary&cell&wall&prevents&the&cell&from&bursting&due&to&the&incoming&water.&e. Why& do& plants& wilt&when& not&properly&watered?&How&is& the&cell& wall&affected&during&drought?& Plant&wilting&is&the&result&of&an& insufficient&turgor&pressure.&During&drought&the&cell&wall&helps&maintaining&the&structural&integrity&of&the&gree n&pa rts&of&the&plan t,&such &as&stem s&and &leave s.&Exten sive&dro ught&may&result&in&dehydration&of&the&cell&wall&matrix&made&of&pectins&and&the&cell&wall&would&collapse.&&2. Name&the& main& components& of&animals’&extracellular&m atrix?&The&animal&extracellular&m atrix& (ECM)&consists&of&collagen,&gelGforming&polysacch aride s,&in te gr ins ,&a nd &fib r on e c tin s. &a. What&is&the&function&of&the&E C M?&&The&ECM&main&function&is&structural&support.&b. What&is&so&special&about&collagen&and&the&other&ECM&proteins&that&is&advantageous&for&the&structure&and&functio n &of&animal&cells.&&Collagen,&the&main& component,& is &very&elastic&and&benda b l e &(com p a re d &to& cellulose& of& plants)& wh ich& m ake s& the& stru cture & pliable.& It& is& not& rigid& so& it& can& adjust& itself&depending&on&its&environment.&c. You&are&given&a&picture&of&a&certain&group&of&cells&an d&are&asked&to&identify &whether&they&are&bone&cells&or&skin&cells.&How&can&you&decide&what&sort&of&cells&you&are&looking&at?&It&would&be&helpfu l&to&look&at&th e &ECM&of&bone &and&skin &(see&google&images).&Bon e &has&relative ly&few&cells&but&lots&of&E C M&while&skin&cells&have&many&cells&tightly&packed&tog eth er&w ith&limited &EC M .&d. Using&the&example&of&bone& and&skin,&how&does& the&structure&of&ECM&relates&to& the&function?&The&amount&of&ECM &relates&to&the&function &of&th e&cells:&b on e&is&supporting&structure&thus&contain&la rge &amount& of& extracellular&su ppo rting& material& (ECM )&that&consists&of&collagen&fibers&embedded&in&a&matrix&rich&in&calcium&and&phosphorus.&Skin&cells&form&epithelial&tissue&that&lines&surfa ce &o f& the & bo dy,&making& waterproof& coat& that& protects& underlining& structures,& thus& cells& in& skin& are& tightly& packed&together&with&lim ited&E CM.&e. In&certain& resea rch& labs,& the& en z y m e & tr yp s in & is& u s ed & t o & b re ak & a p ar t& ce lls & fro m& each& oth e r & an d & the&surface.& What& might& trypsin& b e& doing ?&&Trypsin&is&a& peptidase,& a& digestive& enzyme& produced& by&Biosc&0150:&Foundations&of&Biology&I.& & Review4:&&Chapter&8&&&9& & Adel,&Anthony,&Kathleen,&Megan,&Dr.&Swigonova& & Page&2&of&14&pancreas& (as& a& proenzyme& trypsinogen)& that& hydrolyses& proteins& by& cleaving& peptide& chains& at&specific&sites.&The &tar ge t&pr ot ein s&a re &the &su rfa ce &pro te in s&in vo lv ed &in&c ell&a dh e sio n .&When& the&ECM&is&broken &d o w n ,&ce lls &w ill&h a ve &a &ha rd &t im e &a tta c hin g &th e mselves&to&surfaces&as&well&as&other&cells.&&3. Explain&the&relation&of&each&of&the&following&structural&componen ts&of&the& ECM :&integ rin ,&fib ro n e c tin ,&co llag e n .&Draw& a& picture&and&label&the& stru ctu res.& The& transmemb rane& protein& integrins& (attached& to&actin&filament&inside&the&cell)&helps& hold&a& cell& in&place& by& binding&to&nearby& proteins,& including& fibronectins,& which& bind& to& collagen&fibers.& This& linkage& is& between & the& integrin ,& fibronec tins,& and &collagen&is&what&holds&a&cell&in&place. &a. If& in te g rin & wer e & remo v e d & from& a& cell,& wh at& would & be& the&consequences?&&The& cell& would& probably& n ot& be& ab le& to& stay&in&place.&b. What& must& happen& for&cells& to& metastasize&and& migrate& through&the& body?&&The&cell’s&cytoskeletonGECM&linkage&must&break&down&to&allow&the&cell&to&move&form&one&place&to&the&other.&&c. Where&are&most&ECM&components&synthesized?&&They&are&mostly&synthes ize d &in &t h e &RER.&d. Through& w hat& process& are& these& compo nents& moved& out& of& the& cell?&&These& compo nents& are&secreted&from&the&cell&via&exocytosis&(don’t&forget&the&endomembrane&system&and&how&it&works!)&&4. CellGCell&Attachments&a. The& extracellular& space& between& ad jacent& plant& cells& comprises& of&how& many& layers?& & Name& these& layers.& & What& is& this& “glueGlike”&middle&layer&made&up&of?&Draw&a&picture&and&lable&the&components.&3;&Cell&wall&–&middle &la mella&–&ce ll&w a ll;&g e la tinous&pec tin s &&&b. Compare&and&contrast&primary&and&secondary&cell&wall.&Primary&cell&wall&is&produced&first&and&is&relatively&thin&and& flexible,&allowing&& the&cells& to& grow.& Once& cells& cease& to& grow,& they& commonly& secrete&secondary&