lectures 3-4 Flashcards
define amphipatic
a molecule with both hydrophobic and hydrophilic parts
what is the role of steroids in a biomembrane
act as hormones (sex hormones) and maintain membrane stability (cholesterol)
what is the exoplasmic face
the surface of the plasma membrane directing towards the extracellular environment and away from the cytoplasm
what types of molecules can pass through the semi-permeable membrane
hydrophobic
uncharged - non-polar
small
what is a ‘lipid raft’
membrane region that assembles specialised lipids and proteins to perform a certain task
what are the functions of proteins in the plasma membrane
anchorage to extracellular matrix and intracellular cytoskeleton
cell to cell communication
transport across membranes
give examples of stimuli to open a gated channel
mechanical stress
change in voltage
change in temperature
binding of a ligand
what are the 4 lateral junctions in epithelium
desmosomes
gap junctions
tight junctions
adherens junctions
what are the two basal junctions in epithelium
hemidesmosomes
extracellular matrix
tight junctions
hold cells together
act as diffusion barrier
consist of plasma-membrane proteins
(claudin, occuldin)
gap junctions
field of connecting channels made of connexins
allow passage of small molecules and ions between adjacent cells
adherens junctions
cadherens forms bridges between cells
catenins link to actin cytoskeleton
desmosomes
catherin proteins interact with intermediate filaments in the cytoskeleton and resist shear force in epithelia and muscle
hemidesmosomes
contains integrin proteins that interact with extracellular matrix and anchor epithelial cells to basal lamina
extracellular matrix
fibres of secreted proteins (collagen, matrix proteins, glycoproteins) that hold tissue together and provide strength
