Lecture 3- cell membranes

Membraneiscomplex 8 membrane carbohydrates are

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: terol" holds"them"intact 17 Diagram of the structure of the cytoplasmic membrane 10:25 Gardiner 2013 18 6 The Thickness – 8000 staked would be the thickness of a page in our text book BIOLOGY • Approx. 8 nm thick (7 – 9) 1202B 10:25 Gardiner 2013 19 Proteins may have membrane spanning α-helices - Proteins have a primary structure, secondary struture, tertiary structure- each structure causes conformational changes in the molecule Example: 7-TM receptors for signalling molecules, for instance adrenalin and glucagon 20 • Proteins determine most of the membrane’s specific functions. • The plasma membrane and the membranes of the various organelles each have unique collections of proteins. • There are two populations of membrane proteins. – Peripheral proteins - not embedded in the lipid bilayer – loosely bounded to the surface, often connected to the other population of membrane proteins. 10:25 Gardiner 2013 - Proteins can be divided in different categories: (1) peripheral proteins - surface proteins - do not interact with the hydrophobic core of the membrane - made up of a mixture of polar and nonpolar amino acids - held to membrane surfaces by noncovalent bonds 21 7 – Integral proteins penetrate the hydrophobic core of the lipid bilayer, often completely spanning the membrane (a transmembrane protein). (2) Integral proteins - span the membrane - proteins embedded in the phospholipid bilayer- • Where they contact the core, they have hydrophobic regions with nonpolar amino acids - alpha helices. • Where they are in contact with the aqueous environment, they have hydrophilic amino acids. - go right through the membrane - A subset of integral membrane proteins that traverse the entire lipid bilayer are referred to as transmembane proteins - The domain that interacts with the lipid bilayer (core)consists predominantly of nonpolar amino acids- alpha helix (hydrophobic) - The portions that are exposed on either side of the 10...
View Full Document

Ask a homework question - tutors are online