John   Lenyo
Corrina   Perez
Hazel   Owens
http://micro.magnet.fsu.edu/cells/plasmamembrane/plasmamembrane.html

• Cell   membranes   are   composed   of   proteins   and   lipids.
• Since   they   are   made   up   of   mostly   lipids,   only   certain   substances   can   move   through.
spmbiology403.blogspot.com

• Phospholipids   are   the   most   abundant   type   of   lipid   found   in   the   membrane.
Phospholipids   are   made   up   of   two   layers,   the   outer   and   inner   layers.
The   inside   layer   is   made   of   hydrophobic   fatty   acid   tails,   while   the   outer   layer   is   made   up   of   hydrophilic   polar   heads   that   are   pointed   toward   the   water.
academic.brooklyn.cuny.edu
• Membrane   structure   relies   on   the   tendency   of   fatty   acid   molecules   to   spread   on   the   surface   of   water.
• Membrane   proteins   (which   take   up   half   of   the   membrane)   determine   what   gets   into   and   leaves   the   cell.
• Glycolipids   are   found   on   the   outer   part   of   the   cell   membrane.

• Single   chain   lipids   were   assumed   to   be   the   first   of   those   to   form   cell   membranes   with   the   more   complex   phospholipids   evolving   later
• Phospholipids   can   be   synthesized   in   an   abiotic   environment   without   enzymes   now
• Phosphoplipid   bilayers   now   make   up   the   plasma   cell   membranes   that   regulate   movement   into   and   out   of   prokaryotic   and   eukaryotic   cells.
Single   chain   lipid http://clincancerres.aacrjournals.org/content/11/5/2018/F1.
expansion http://web.nestucca.k12.or.us/nvhs/staff/whitehead/homewor k.htm

• Today   Plasma   Membranes   are   made   primarily   of   phospholipids
• It   is   thought   that   early   membranes   may   have   been   made   of   simpler   fatty   acids.
http://exploringorigins.org/fattyacids.html

• They   are   Ampipathic,   meaning   that   they   have   a   hydrophobic   (“water   hating”)   end   and   a   hydrophilic   (water   loving”)   end.
• Hydrophobic   molecules   are   nonpolar.
They   prefer   other   neutral   or   non ‐ polar   molecules   and   avoid   polar   molecules,   such   as   water.
i.e.
oil   and   vinegar http://www.cool
‐ science ‐ fair ‐ experiments.com/oil ‐ and ‐ vinegar ‐ separation ‐ experimen/
• When   fatty   acids   or   phospholipids   are   put   into   an   aqueous   solution,   they   will   self ‐ assemble   into   a   ball.
Their   hydrophobic   ends   will   face   inward   and   hydrophilic

• Micelles   are   basically   spheres   of   fatty   acids.
• They   will   self ‐ assemble   in   an   aqueous   solution   in   low   concentrations
• Their   hydrophilic   ends   point   outward   making   contact   with   the   water   and   the   hydrophobic   ends   cluster   together.
http://en.wikipedia.org/wiki/File:Micelle_scheme ‐ en.svg

• Research   from   the   Stoztak   Lab   at   Massachusetts   General   Hospital   has   shown   that   micelles   can   form   vesicles   under   the   right   conditions
(pH,   concentration,   etc.)
( http://genetics.mgh.harvard.edu/szostakweb/researchVesicles.html
) http://en.wikipedia.org/wiki/File:Lip osome_scheme ‐ en.svg
• Vesicles   are   membrane ‐ enclosed   sacks   that   form   in   aqueous   solutions
( http://en.wikipedia.org/wiki/Vesicle_(biology) )
• Once   formed,   phospholipid   vesicles   are   highly   stable
• Fatty   acid   lipids   are   much   more   dynamic
( http://exploringorigins.org/fattyacids.html
)

• Vesicles   made   of   fatty   acids   are   stable,   but   very   dynamic.
Fatty   acids   are   constantly   flipping   in   and   out   of   the   membrane.
• This   may   have   provided   the   opportunity   for   other   monomers   or   macromolecules   to   enter   the   vesicle.
http://genetics.mgh.harvard.edu/szostakweb/exploringOriginsDownloads/p rotocell.jpg

• In   a   cooperative   effort   from   Harvard   and   other   genetic   research   institutions   efforts   are   being   made   to   replicate   working   vesicles   from   plasma   membranes.
http://genetics.mgh.harvard.edu/szostakweb/researchVesicles.html
http://www.hms.harvard.edu/dms/prospective/AboutDMS.html

• Some   scientists   propose   that   early   earth   had   the   capacity   to   form   fatty   acids,   most   likely   near   hydrothermal   vents
• Clays   are   thought   to   have   played   a   role   in   catalyzing   the   formation   of   fatty   acid   tails   from   H   and   CO2   gases.
• In   large   enough   quantities,   these   fatty   acids   have   been   shown   to   self ‐ assemble   into   micelles,   or   vesicles
( http://exploringorigins.org/fattyacids.html
)

• Research   has   shown   that   the   clay   montmorillonite   can   catalyze   the   formation   of   vesicle   formation
( http://exploringorigins.org/fattyacids.html
)
• The   vesicle   is   crucial   to   the   formation   of   the   protocell   and   is   thought   to   be   the   precursor   to   the   cell   membrane
• Today,   however,   plasma   membranes   are   synthesized   and   regulated   by   the   cell.

• European   Researcher   Pascal   Jonkheijm   is   working   to   create   artificial   cell   membranes   on   microchips   to   better   understand   how   cells   communicate   with   each   other
• Jonkheijm   believes   that   the   knowledge   he   gains   can   be   a   stepping stone   into   regenerative   research.
http://www.nanowerk.com/news/newsid=18101.php
http://www.utnieuws.utwente.nl/new/?artikel_id=76814