Week 3 MPW Lecture 2 Flashcards
What is the size difference between eukaryotic and prokaryotic cells?
Eukaryotic cells are about 1000x larger in volume (10x linear dimensions) than prokaryotic cells
Since the eukaryotes are large, how does the eukaryotic cell function with its large size?
By compartmentalisations – separating the cells function in different places. Most eukaryotes vesicles function are in a membrane bound vesicle.
What are membranes made out of?
Membranes are made of lipids, which are hydrophilic at one end and hydrophobic elsewhere. Therefore, in water they spontaneously aggregate together.
What type of structures can be made with lipids?
In the lab, they can aggregate into many different structure (lipid bilayer, liposome, vesicle) but in cells they just aggregate into bilayers.
How is the fluid mosaic structure made?
Hydrophobic proteins through into the bilayer, producing the fluid mosaic structure. Hydrophilic proteins are usually on the surface of the bilayer.
What type of proteins are bound to the membrane?
So;
a) Lipid anchored protein
b) Integral membrane protein
c) Peripheral membrane protein
What is a Lipid anchored protein?
only going halfway in
What is an Integral membrane protein?
running all the way across
What is a peripheral membrane protein?
stuck to an intrinsic protein
Do membrane proteins move? If so, how are they detected?
Yes, can be detected by FRAP (fluorescence recovery after photobleaching)
a) So first we label the membrane proteins
b) Bleach the labels with a laser
c) Track the movement of the bleached proteins
i) From the tracking of the proteins we can see that some of the proteins are ‘recovering’, this as some lipids are free to move, other are immobile
What does an atomic force microscopy (AFM) image of a membrane show?
This shows the height of different components (rafts) and shows proteins embedded in the membrane sticking up above the lipid bilayer.
What is a vesicle?
membrane-enclosed bag produced by the cell - for example for exocytosis (secretion) or endocytosis
What is a liposome?
membrane-enclosed bag but is produced by humans, It is normally a simple spherical container made from a lipid suspension.
