Lectures 15 Membrane Structure and Transport-BW

2000 lectures 15 lipid bilayer is a favored structure

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: is a Favored Structure Membranes form due to the amphipathic property of phospholipids: Box shows the plasma membrane is a bilayer ***Hydrophobic Effect Polar head group interacts with water. Hydrophobic tails interact with each other; avoid water. 3/11/13 MCB 2000 Lectures 15 Eukaryokarote membrane - not plants they dont have c holesterol - the mam. c onstatn colesterol - most importantly the plasma membrane - has ring s tructure - very planar and hydrophobic - you have one hydroxyl group gives cholesterol the imporant property c onsidered amphipathic Membrane Components The precuroser for making steriod hormones - derivie from steriod nueculus Also amphipathic High content in plasma membrane; found in animal, not plant membranes 3/11/13 MCB 2000 Lectures 15 Membrane Fluidity Depends on properties of fatty acid chains in phospholipids Length of chain Double bonds O rganisms and plants can modifi ty - to withstand heat and cold - membrane fl uidity - when you talk about a membrane gonig to have some types of s olid and fl uid characteristics - the more fl uid it is the greater the permeability - because not packed as tightly - what to restict permebailty - pack in molecules closer together ( or more fatty acids taht are saturated in your phosphlipds) - two factos that c ontrol fl uid (one fatty acid and one cholroesteol) focusing on the plasma membrane - plasma highest in choldestrol - property of the fatty acid - if y ou have a saturated fatty acid - can pack mulit phosphlipdi tightly - saturated and unsatured fatty acid - will open up some space - waht determines the fl uidity? - going to put in unsaturated other factor is the life of the cahin - long chain fatty acid ( 18 carbons) verus 4 or 6 which is more fl uid? shorter or longer chain? - short chain because n /11/13 3oncoavalent interaction contribue to stability s horter the chain the fewer of the interactions MCB 2000 Lectures 15 Membrane Fluidity Cholesterol content (animal cells) -OH groups forms H-bond with carbonyl of phospholipid head group Can from complex with specific phospholipids (sphingolipids); may increase rigidity and order in Choldestoral can interact with polar head of the phosplipd bilayer - cholesterol going within the regions of membrane, i.e. tail - one level cholesterol increase membrane fl uidity because it distrubtes the interaction between the hydrophoic tail and seprates them out - however there are regions of the lipid rafts membarne that are more enriched with phosphlipid - can be present in the membarne and they are typically located in pathches - not uniformity distributed - choldrestol interacting with spingolipds - arrangedment - lipid wrap - region of the membrane - unique - signal trasnductino r oles - endocytosis - membrane dynamics - within the region goingt have a decrease in 3/11/13 MCB 2000 Lectures 15 membrane fl uid - cholesterol has two opposing effects - increase infl uid if evenly distrubted s ingle lipid more ridgid - important effects mi...
View Full Document

Ask a homework question - tutors are online