membrane structure and membrane proteins

how are organelles distributed within the cell

they are nonrandomly distributed and have preference due to function

what are the most abundant cellular lipids

phospholipids

what are the two classes within the 5 major phospholipids

1. sphingo

2. glycerol

what are the 4 major phospholipids in the mammalian plasma membrane

1. phosphatidylethanolamine

2. phosphatidylserine

3. phosphatidylcholine

4. sphingomyelin

what are sterols

sterols are a class of molecule that is characterized by its 4 ring structure

why is cholesterol an important part of the membrane

it can be used as a precursor for other sterols and is small enough to be inserted between normal phospholipids

what is the function of cholesterol in membranes

reduces mobility of phospholipids

what is an example of the number of tails in a phospholipid affecting the way they congregate together

one tail phospholipids form micelles and two tailed phospholipids end up forming a lipid bilayer

why does spontaneous closure of phospholipid bilayers happen frequently

it is because the sealed compartments are more energetically favorable

what structure do membrane spanning regions of proteins tend to be

alpha helical

what about alpha helical structures make them so good to be able to traverse through membranes

their structure maximizes hydrogen bonding which helps stabilize the hydrophobic portion

is it possible for transmembrane proteins to not be identified by a hydropathy plot and if so why

yes, and it is possible because they can associate with other transmembrane portions without actually being transmembrane themselves.

what structure do transmembrane regions of proteins take if they pass through the membrane multiple times

betta sheet(beta barrel)

what can be used to extract membrane proteins

detergent

what can anchor proteins to the membrane

• transmembrane portion

• lipids

• non-covalent interactions from other proteins

can macromolecules be segregated without a membrane

yes, they can do it through condensate formation

how do condensates form

they form via multivalent interaction