Membranes Flashcards
membrane asymmetry
the inside and outside of the plasma membrane are not the same
why do phospholipid bilayers form
due to a hydrophobic tail and hydrophilic head (amphipathic)
what are membranes influenced by
lipid type and concentration
what does the fluid mosaic model show
that membranes move (are fluid)
why does it matter that membranes are fluid
matters for proper function, adaptability, and homeostasis
factors that influence membrane fluidity
temperature, structure and composition of phospholipids (kinks?), cholesterol levels
structure of saturated hydrocarbon tails and affect on membrane
no double bonds meaning no kinks/bend, makes more viscous membrane
structure of unsaturated hydrocarbon tail and effect on membrane
double bonds present meaning more kinks/bends, meaning more fluid
what does it mean when phospholipids have longer tails
makes a more viscous (tighter bound) membrane
importance of cholesterol in membranes
helps maintain proper membrane fluidity in response to temperature changes (fluidity buffers)
function of membrane proteins
transporters, enzymes, signal transduction, cell surface attachment and recognition
types of membrane proteins
integral membrane proteins and peripheral proteins
where are peripheral membrane proteins located
on the surface of the plasma membrane
where are integral membrane proteins found
on both sides going through the plasma membrane
how can an integral membrane protein cross the membrane bilayer
stretches of non-polar amino acids
types of transport across the membrane
passive, active, and endo/exocytosis
difference between passive and active transport
passive- no energy required, moving with the concentration gradient
active- energy required, moving against concentration gradient
types of passive transport
simple diffusion and facilitated diffusion
simple difusion
things move through plasma membrane (bounce against each other) until they reach equilibrium
what can go through membrane in simple diffusion
non-polar molecules and small uncharged polar molecules
facilitated diffusion
membrane proteins form a channel to facilitate diffusion across the membrane
is facilitated of simple diffusion faster
facilitated
types of proteins
channel proteins, gated channel proteins, and carrier proteins
which protein channel is made for large molecules
carrier proteins
types of active transport
primary and secondary
primary transport
uses ATP to move molecules against concentration gradient (often out of cell)
secondary transport
uses electrochemical gradients as energy (acts like a seesaw with ions, as one goes down the other goes up and vice versa)
what is symport
type of secondary active transport where the ions move in the same direction as the driving ion (both go in or out)
what is antiport
secondary active transport where ions moves in direction opposite form the driving ion (one goes in other goes out)
exocytosis
vesicle moves things to the outside of cell and exports them (kicks them out)
bulk-phase endocytosis (pinocytosis)
vesicle imports water and other substances from outside the cell inside
receptor mediated endocytosis
vesicle imports specific molecules as they attach to receptors
phagocytosis
when the cytoplasm extends outwards to “eat” its prey
what is osmosis
the regulation of water movement as the water
in osmosis what passes through the membrane
water, solute cannot pass through
where does water want to go in osmosis
moves to where the solute is (make it equal on both sides)
what does hypo mean in osmosis (hypotonic)
less solute in the surrounding environment
what does hyper mean in osmosis (hypertonic)
more solute in the surrounding environment
signal transduction step 1
reception- binding of a signaling molecule to a receptor on the outside of cell
signal transduction step 2
transduction- signal changed into form for the cellular response, often a signaling cascade
signal transduction step 3
response- signal causes a specific cellular response depending on signaling molecule
what is a kinase
an enzyme that adds phosphate (phosphorylates other proteins) using ATP
