braneFunctions Me m
S le e ctiveBarrie r
Transport S m yste s Enzym S m e yste s for Ene Me rgy tabolism
C ll e S ignaling
Me braneFunctions m
Me brane cre ce com m s ate ll partm nts through se ctivepe e e le rm ability. C ll com e partm nts can haveindividually controlle e d pH, m cular conce ole ntrations, and charge diffe ntial. re Re ptor prote allow: ce ins C ll-ce re e ll cognition. C ll signaling. e Me brane can control re m s action se nce que s. C hargediffe nce across m m re s e brane can se ne s nd rve im pulse and drivece re s ll actions.
Me brane arecom d of lipids and prote m s pose ins. Lipids providethestructureand prote providethe ins function.
Me braneC pone m om nts
Ele ctron m icrograph of m lin inne m m ye r e brane . Mye insulate lin s thechargeon ne rve fibe rs.
Me brane m C pone om nts
Phospholipids cholesterol phospholipid bilayer fluid mosaic model glycolipids glycoproteins
Me branePrope s m rtie
Fluidity Pe iability rm I nsidevs Outside Transport Prope s rtie C hargeand pH
Me branePrope s m rtie
I n ge ral, thephospholipids and ne prote in m m ins e brane arefre to s e m late ove rally but, only ve rare ry ly flip.
How do weknow that?
Oneway is fromm aking m ouse hum hybrid ce an lls.
Add PEG or Sendai virus
Fre zefracturele you e ts cut m m e brane in half and s se e phospholipid le t. e ach afle
Which part of a m m e branegive s it its fluid characte ristics?
Membrane Fluidity
Me brane m re ain fluid for asse bly and biological m s ust m m functions Bacte and ye adapt to varying te pe ria ast m rature by s changing thele ngths and theunsaturation of the tails ir m unsaturation = m fluid ore ore Anim ce re al lls gulatefluidity with chole rol ste
The most common fatty acid is palmitate.
Plasm m m a e brane have s ne onechole rol pe arly ste r phospholipid m cule ole .
C ste hole rol
C ste m s thelipid bilaye le hole rol ake r ss de ableand de ase its pe e form cre s rm ability to sm wate all r-solublem cule ole s by partially im obilizing thephospholipid m cule ne to e m ole s xt ach chole rol m cule ste ole . Without chole rol, anim ce would ne d ce walls. ste al lls e ll
What fe aturein a m m e brane he to prevent lps freezing?
S chain hort fatty acids m lt at e a lowe te pe r m raturethan long chains. Unsaturate fatty acids d re ain fluid at lowe te pe m r m rature s than saturate fatty acids. d
Permeability
Me brane areim rm able m s pe e to ce rtain m cule ole s. How do the m cule e r se ole s nte thece ll?
Protein Glycosylation
Oligosaccharidesidechains areadde (sugars) to d m prote in theER and arethe m any ins n odifie in d theGolgi apparatus. Glycosylation se s various functions including rve prote ction fromde gradation, transport and packaging signals, and ce com unication whe ll m n displaye on theoute m m d r e brane .
I n glycolipids, as with glycoprote ins, thesugar portions of them culearefacing ole thee xtrace llular space .
Membrane Structure Review
De scribethefluid m osaic m l of m m ode e brane structure . What is them abundant lipid in m m ost e brane s? How do bacte and ye m ria ast odulatem m e brane fluidity? How do anim ce m al lls odulatefluidity?
Cell Membrane Function
Transport Re cognition C ll S e ignaling
Bulk Transport Endocytosis Exocytosis Pinocytosis
(figureadapte fromAlbe e al.,1994, Mole d rts t cular Biology of theC ll) e
Theroleof clathrin, adaptin and yolk prote in receptors in the inte rnalization of yolk prote by de loping ins ve oocyte s.
(figureadapte fromAlbe e al.,1994, Mole d rts t cular Biology of theC ll) e
Adaptin binds cytoplasmic tail of receptor.
Clathrin binds adaptin deforming membrane to form bud.
(figureadapte fromAlbe e al.,1994, Mole d rts t cular Biology of theC ll) e
FROM GENE TO DNA TEC HNOLOGY
C S ase tudy: Fam HYPERC ilial HOLES TEROLEMI A RFLP ge m ne apping cDNA PC R in-situ hybridization ge cloning ne knock-out ge s ne ge the ne rapy
Re re s: fe nce Theinform ation about FH on the se slide is e rpte fromOnline s xce d Me lian nde I nhe ritancein Man http://www.ncbi.nlm .nih.gov/O m / im
Fam HYPERC ilial HOLES TEROLEMI A Background an autosomal dominant disorder characte d by rize e vation of se chole rol bound to low-density le rum ste lipoprotein (LDL), re sulting in m dly incre d chole rol arke ase ste le l and an incre d incide of e onse of athe ve ase nce arly t roscle rosis and its com plications. Mutations in theLDL receptor (LDLR) ge on ne chrom osom 19 causethis disorde e r. Occurance about 7 out of 1000 people. :
TheLDL re ptor was ce discove d through an re e xtraordinary collaboration be e two e twe n xtraordinary scie ntists, Michae S Brown l . and Jose L. Goldste ph in.
C lls that ne d chole rol synthe LDL re ptors. e e ste size ce
from Alberts et al. Molecular Biology of the Cell, Garland Publishing, Third edition, 1994.
C lathrin Pits
Mole cular Transport PassiveDiffusion Facilitate Diffusion d ActiveTransport
Gap Junctions allow com unication m be e ce twe n lls. S all m cule and m ole s ions can pass through.