Plasma Membranes Flashcards
what compound allows animal cells to exist without a cell wall.
cholesterol within the phospholipid layers
what does cholesterol within the phospholipid lipid layers do?
it creates a rigid and impermeable cell wall in animal cells
what are transmembrane proteins?
proteins that cross both layers of the bilayer
they are integral
they generally cannot leave
what role do many transmembrane proteins play within the cell?
many are carrier or channel proteins
what are peripheral proteins?
they only interact with the membrane temporarily and can interact with the phospholipid bilayer or attach to a transmembrane protein
what can peripheral protein interactions cause?
different responses e.g. tell a transmembrane channel to close - which is important to cell signalling
what is the extracellular matrix?
the surroundings of an animal cell that consists of glycoproteins, polysaccharides and other things.
what does interstitial mean?
connects between nearby cells that arent attached to each other
can the extracellular membrane be interstitial?
yes
what is a base membrane?
a base that cells can be attached to giving them strength and stability.
what are glycoproteins/glyoclipids?
chains of sugars attached to proteins or lipids
where are glycoproteins/glycolipids located?
only on the outside of the cell
what role to glycoproteins/glycolipids play?
they are very important for cell-cell recognition
what is the defining factor for blood type?
the different glycoproteins attached to the outside of red blood cells (determines blood type)
what determines the fluidity of the phospholipid membrane?
the number of unsaturated lipids in the phospholipd tails
what are microdomains and how are they formed?
a collection of proteins and lipids that are floating within the membrane
what can happen when two cells fuse?
the proteins in their membrane can mix
which kind of molecules can cross the membrane unaided?
small hydrophobic molecules
and very small non-ionic molecules
what kind of molecules require protein channels to cross the membrane?
most small hydrophilic molecules
which molecules are unable to pass through the membrane?
larger molecules
when does diffusion occur?
constantly and naturally to reach equilibrium
which specialized transport mechanisms are needed for diffusion to occur?
none
what is osmosis?
the diffusion of water
what is required for osmosis to occur?
specific channels - aquaporins
what is a hypertonic solution?
when water is lost from the cell through osmosis
what is a hypotonic solution?
when water is gained from the cell though osmosis
what is an isotonic solution?
when water is neither lost or gained from the cell via osmosis
what disease is related to issues with osmosis in the body?
diabetes
what are epithelial cells?
cells that line the outside of surfaces of tissues
what sort of channels are aquaporins?
chanel proteins - always open
what sort of proteins do Na+ and K+ ions travel through?
chanel proteins
what are carrier proteins used to transport?
larger chemicals e.g. glucose or neurotransmitters
do all carrier proteins carry all chemicals ?
no, all chemicals e.g. neurotransmitters have their own families of carrier proteins for transmission
what are gated proteins?
channel proteins that can be controlled by voltage across the membrane or contact with a signalling molecule or chemical.
what would cause short-term effects with gated proteins?
voltage across the membrane
contact with a signalling molecule
what would cause a long-term effect with gated proteins?
chemical changes within the cell e.g. phosphorylation
what is a uniporter?
a carrier protein that allows 1 thing across the channel from extracellular to intracellular
what is a symporter?
where 2 molecules can quickly be passed across the membrane at the same time (in the same direction)
what is an antiporter?
where two molecules can pass across the membrane, at the same time, in different directions
what is a faster transporter - a symporter or an antiporter?
a symporter
what example of transport requires energy ?
Na+ and K+ pump
how are molecules transported across the membrane?
using energy from ATP
what happens in a Na+ - K+ pump
3Na+ leave the cell and 2K+ come into the cell
what is endocytosis?
where target materials bonded to the membrane are brought into the cell when the membrane invaginates to form a vesicle.
what is exocytosis?
where vesicles meet the membrane and fuse, then release the contents from the cell e.g. neurotransmitters on synapses.
