Cell Physiology - memebrane Flashcards
membrane structure
phospholipid bilayer, cholesterol, proteins
phospholipid head
hydrophilic
phospholipid tail
hydrophobic
membrane cholesterol
found in outer membrane (primarly), SLIGHTLY amphipathic, maintain membrane fluidity
amphipathic
having both hydrophobic and hydrophilic parts
two classes of membrane proteins
- integral membrane proteins
- peripheral membrane proteins
integral membrane proteins
embedded in the membrane / membrane spanning (transmembrane proteins). Amphipathic
peripheral membrane proteins
NOT amphipatthic, lie on membrane surface, bound to polar regions of integral proteins, mostly on cytosolic surface
membrane function
link adjacent cells together, regulate passage in and out of cells, detect chemical messengers arriving at cell surface, anchor to extracellular matrix
cell junctions
important in formation of tissues.
1. desmosomes
2. tight junctions
3. gap junctions
desmosomes structural charaistics
firm attachedment between cells gives structural integrity, form dense plaques, 20nm space b/w adjacent cells.
desmosomes proteins
cadherins (extend into extracellular space and bind with cadherins form adjacent cells), keratins (anchor desmosomes to cyotosketetons)
tight junction structure
no space between adjacent cells,occurs in band around whole cell, common in epithelia.
tight junction proteins
complex, over 40 proteins. occludins, claudins
gap junction structure
adjacent cells sperated by 2-4nm, form proves b/w cells allowing passage of ions and molecules (small)
