B2.1 Flashcards
Membranes and Membrane Transport
what macromolecules are in membranes
proteins
lipids
small carbs
what are the major classes of lipids
phospholipids
glycolipids
sterols
describe what a phospholipid looks like
modified glycerol molecule with a neg charged phosphate group and two fatty acid chains
describe phospholipids in an aqueous environment
tails point inward
where is cholesterol located
between tails
term for water loving and hating
amphipathic
what can pass through the membrane
steroids
lipid soluble
small uncharged (h20, o2)
what is permability reliant on
hydrophobic/hydrophilic nature
what is simple diffusion + example
the passive transport of molecules from high to low concentration
diffusion of oxygen from high to low concentration in red blood cells
what is a transmembrane protein
a protein that extends fully across a membrane (integral)
explain the polarity of integral proteins
top/outer part is hydrophilic and interacts with the heads, while the inner part is hydrophobic and interacts with the tails
explain the polarity of peripheral proteins
hydrophilic and interacts with the heads
4 functions of membrane proteins
cell - cell recognition
transport
receptors
enzymes
function of transport proteins + 2 types
facilitate movement
channel proteins
- form channels for movement
carrier proteins
- conformational change
function of recognition proteins
distinguish between self and non self cells with cell - cell recognition
function of receptor proteins
binding of molecules to this protein can facilitate reactions or processes
function of enzyme proteins
catalyze reactions
what are aquaporins
integral proteins that speed up the movement of water down a concentration gradient
Facilitated diffusion
movement of solutes down a concentration gradient monitored by size and polarity
movement is mediated by size and polarity
aided by channel and carrier proteins
what type of protein is used for ion pumps
channel proteins
what decides the ion used for the channel protein
binding sites being highly specific
what forms of stimuli can open/close
changes in voltage
binding of molecules (ligand gated)
how do carrier proteins transfer molecules
undergo conformational change and binds to the solute
what is active transport used for
transporting nutrients against a concentration gradient
remove waste
maintain concentrations
two types of active transport
direct –> regular, uses atp
indirect –> movement of one down its gradient makes another against its gradient
two classes of recognition proteins
gated ion channels
specific carrier proteins (GLUT)
types of glycolipids
glycoglycerolipids –> based on glycerol molecules
glycophingolipids –> derivatives of sphingosine
how do glycolipids contribute to membrane stability
forms h bonds with mobile water
functions of glycolipids and glycoproteins
cell - cell recognition
cell adhesion
cell signalling
what is glycocalyx
sticky layer formed by surface of glycolipids and glycoproteins
what contributes to the fluid mosaic model
lipids and proteins can move freely in the membrane
