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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
– Peripheral proteins - not embedded in the
– loosely bounded to the surface, often
connected to the other population of
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
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...
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