Class Notes (1,100,000)
CA (630,000)
UTSC (30,000)
BIOB10H3 (300)
Lecture

Important Terms and Definitions


Department
Biological Sciences
Course Code
BIOB10H3
Professor
Aarti Ashok

This preview shows half of the first page. to view the full 2 pages of the document.
LECTURE#5
x A function of the plasma membrane is that it serves as a scaffold fro biochemical activities eg.
signalling proteins send signals to the nucleus
x It allows the cell to respond to extracellular signals eg. signals could tell cels to prepare for cell
division ; cell surface receptors that bind ligand on the cell exterior can send signals into the
cytoplasm of the cell
x PM is a lipid bilayer
x Hydrophobic interactions of the fatty acid tails of the PM
x Protein channels within the bilayer
x Short sugar chains on proteins and lipids are called glycoproteins or glycolipids
x Membrane lipids are amphipathic, contain both hydrophobic and hydrophilic regions; 3tyes
o Phospholipids
o Sphingolipids
o Cholesterol
x Sphingolipids are composed of an amino alcohol with a long hydrocarbon chian called
sphingosine and a single fatty acid chain; fatty acid is attached to the amino group of
sphingosine; ceramide is the simplest sphingolipid
x Glycolipids are formed when a sugar is attached to the terminal alcohol of a sphingosine; certain
viruses and txins eg. cholera/influenza toxins bind to cell surface glycoproteins and gain access
to cells
x 3 types of membrane proteins
o Integral membrane proteins: transmembrane proteins (expand bilayer)
Are single or multipass; can pass through membrane once or several times
CFTP is defective in cystic fibrosis patiens (ccystic fibrosis transmembrane
proteins)
o Peripheral membrane proteins: on cytoplasmic or extracellular side of PM
Often transiently interact with PM eg. response to signals
o Lipid-anchored proteins: can be on cytoplasmic or extracellular side (anchored on wither
side)
On the extracellular side, proteins are attached to a complex oligosaccharide
linked to a phosphatidylinotisol t form GPI glycophosphatidylinisol linked
proteins eg. some receptors such as prion
x Membrane fluidity depends on:
o Temperature
o The types of lipids
o The presence of cholesterol tdisrupts the packing of fatty acid chain
x Transition temperature = the greater the degree of unsaturation, the lower the temperature
beore the bilayer gels; eg. butter gels at higher temp than oil; more trans fats in oil than butter
x Various factors influence the mobility of integral membrane proteins
o Local crowding of proteins; neighbours restrict movement
www.notesolution.com
You're Reading a Preview

Unlock to view full version