Lecture 9 and 10: Introduction to Cellular and Model Membranes Flashcards
What are the biomembrane functions ?
- inside/outside cell life
- selectively permeable barrier
- compartmentalise
- site
- support gradients
- communication
- indentification
- specialised synthesis
- source/sink
- dimensionality reduction
- site of vulnerability
Who discovered the fluid mosaic model ?
Singer an Nicholson
What is the fluid mosaic model ?
2D lipid bilayer in/on which proteins reside
What does the fluid mosaic model allow ?
Both lipids and proteins are free to move laterally in the membrane plane and to rotate about their long axis
What does the fluid mosaic model not allow ?
Lipids or proteins to rapidly change orientation across the membrane
Where are biomembranes ?
Surround the cell
What is the definition of a biomembrane ?
Biomoleculrar lipid leaflet in and on which are situated a variety of proteins and other molecules across and along which information and matter flow
What is fluidity ?
The ability of a lipid to diffuse in the plane of a membrane and for its hydrocarbons to flex and bend
What are fatty acids not found as in membranes ?
Free fatty acids
What are fatty acids ?
Carboxylic acids with non-polar hydrocarbon tails
What is the simplest glycerophospholipid ?
Phosphatidic acid
What is the role of phosphatidic acid ?
Key intermediate in the synthesis of membrane lipids - second messenger
What sits in the outer leaflet f outer membrane of gram negative bacteria ?
AA constituent of lipopolysaccharide
What is spingosine ?
Trans monenoic 18C amino diol
Where might you find sphingolipids ?
Nervous system tissue
What is sphingospine ?
A long chain alcohol with a hydrophobic hydrocarbon tail an amine group to which a fatty acyl chain can attach and an OH group at C1 to which a polar head can attach
What is ceramide ?
Addition of a fatty acyl chain to amino group of sphingosine
How do you form sphingomyelin ?
Add phosphochiline to C1-OH of ceramide
What is the head group of sphingomyelin ?
PC
What is the head group of cereboside ?
Hexode sugars
What is the head group of gangliosides ?
Several sugar residues and one or more N-acetylneuraminic acid
What charge is sphingomyelin ?
Zwitterionic
What charge is cereobside ?
Neutral
What charge is gangliosides ?
Negatively
