2.3.1: Membrane structure Flashcards
What is the general structure of a cell surface membrane
phospholipid bilayer - hydrophilic phosphate head, hydrophobic fatty acid tails - intrinsic protein, extrinsic protein, cholesterol, glycoprotein
how do phospholipids arrange themselves when they are surrounded by water
micelle
how do phospholipids arrange themselves when there is water on two sides
bilayer
state the polarity of the phosphate head and fatty acid tails
phosphate head = polar molecule
fatty acid tails = non polar
what is a glycolipid
a phospholipid with a carbohydrate chain attached
what is an intrinsic protein
they span the entire phospholipid bilayer, most function as carrier or channel proteins
What does a channel protein do
facilitated diffusion of ions, have the ability to open and close - selectively permeable membrane
what does a carrier protein do
facilitated diffusion of polar molecules, active transport of both polar molecules and ions, ability to change shape for the transportation of a molecule
what lining do all transport proteins have (channel and carrier)
hydrophilic lining
what are the three cotransport proteins
uniport, symport, antiport
what does a uniport do
transports proteins that passively transport one specific ion or one specific polar molecule down the concentration gradient
what does a symport do
actively transports two different substances at the same time in the same direction
what does an antiport do
actively transports two different substances at the same time in opposite directions
what are extrinsic proteins
proteins in (extracellular surface) or on (cytosolic surface) one surface of the cell membrane
what is the function of an extrinsic protein on extracellular surface
receptors for hormones or role in cell recognition
what is the function of an extrinsic protein on cytosolic surface
involved in cell signaling or chemical reactions
what are the factors that increase membrane fluidity
temperature increase -> increase in kinetic energy -> increased fluidity in membrane
cholesterol
organic solvents like ethanol dissolves the lipids causing a puncture in the membrane
what is cholesterol and how does it affect membrane fluidity
it is a type of lipid, an increase = reduce of fluidity of membrane -> reducing permeability of the membrane
why do we need cholesterol in the membrane of our cells
to reduce membrane fluidity to stop our cells from being too fluid as the cells would burst open
what is the role of phospholipids
act as a barrier to most molecules
what is the role of intrinsic proteins
transport molecules across the membrane or catalyse reactions
what is the role of glycoproteins and glycolipids
involved in cell recognition, cell signalling and cell attachment
Describe what is meant by the fluid mosaic model in relation to the structure of the cell membrane
·proteins are scattered throughout the phospholipids - looking like a mosaic, proteins dotted throughout the membrane
·each of the components of the membrane can all move in relation to each other - fluid
what model is the structure of the cell membrane widely referenced to as
the fluid mosaic model
