biological membranes Flashcards
(9 cards)
1
Q
what is a phospholipid made from
A
- glycerol head - part of the head of the phospholipids (contains phosphate group)
- 2 fatty acid tails - attached to the glycerol that makes up the tails
- head is hydrophilic and tail is hydrophobic
2
Q
what is the fluid mosaic model of membrane structure and what does it consist of
A
- fluid mosaic model - the cell membrane is a mosaic of components that give the membrane a fluid character and allows the selective exchange of materials
- fluid mosaic model applies to all cells on earth, for all membrane organells
- phospholipids are arranged in a bilayer (two-layers)
- proteins are insterted in the lipid bilayer
3
Q
whats the membranes function
A
- to maintain homeostasis within the cell
- membranes are selectively permeable
4
Q
what can affect the membranes permeability
A
- size of molecules (large can’t, small can)
- charge of molecules (polar/charged can’t, nonpolar/uncharges can)
5
Q
what are the functions of membrane proteins
A
- transport substances in and out
- enzymes - speed up reactions
- cell surface receptors - send signals from outside to inside
- cell surface identity markers - chemical name tags
- cell-to-cell adhesion proteins - join cells togethor
- attachments to the cytoskeleton
6
Q
what structural framework do cell membranes consist of
A
- phospholipid molecules
- embedded proteins
- cholesterol
- glycoproteins and glycolipids
7
Q
what are glycoproteins and glycolipids
A
- are lipids and proteins on the cell membrane surface with short carbohydrate chains protruding out from the cell surface
- are receptor molecules, binding with hormones or neurotransmitters
8
Q
what does cholesterol do
A
- helps to regulate fluidity of the membrane
- provide mechanical stability - without it the cells will burst open as their membrane breaks
9
Q
how does water move across membranes
A
through channel proteins called aquaporins
